· 16 letters o f berzelius transl ation o f b erzelius’ t extbook. the publisher could not...

THE LETTERS OF

BERZELIUS AND SCHO'

NBEIN

THE LETTERS

JONS JAKO B BERZELIUS

AND

CHRISTIAN FRIEDRICH SCHONBEIN

1 8 3 6 - 1 8 4 7

EDITED B"

G EO RG W. A . KAHLBAUM

TRANSLATED B"

FRANCIS V . DARBISHIRE,PH.D .

AND

N. V . SIDGWICK

WI L L I AM S A ND N O R G A T E

HENRIETTA. STREET, CO VENT GARDEN , LONDON

20 SOUTH FREDERICK STREET, EDINBURGH

AND 7 BROAD STREET, O XFO RD

1 9 0 0

EDITOR’

S PREFACE

FO R some time pas t I have been engaged on the bio

graphy of Christian Friedrich Schonbein, the discovererof ozone and the inventor of guncotton,

formerly professorof chemistry and physics at the University of Bale, the

hundredth anniversary of whose birth will be celebratedon the 18th of O ctober of next year . Scho‘nbein’s familyhave assisted me in the kindest manner in this work ;they have placed at my disposal the whole mass of paperswhich this indefatigable physical chemist left behind

,

and the many hundreds of letters which he received .

Such writings, far more than the sifted published

results, give us a true insight into the thoughts of thewriter, and enable us to understand the workings of hismind . We have

,moreover, a never-failing series of

incidental allusions to the conditions,the manner and

the difficulties of sending letters,the calculation of the

cost of postage,and the time taken in travelling ; and

thus there develops almost insensibly before our eyes apicture of a bygone age, which forms a background tothe image of the writer himself. We are continuallymeeting with casual remarks

,begotten of the confidence

of the moment, which reveal to us ever new traits ofcharacter, and seem to bring the writer before us in person,and to turn into tangible figures those who before wereto us often only names and shadows .

{ G t-7 14

6 PREFACE

The letters which Sch '

onbein left behind cover a periodof nearly fifty years . They begin in the year 1820 and

extend to his death in 1868. Among their writers are

to be found the most illustrious men of the time . The

greatest of all is Faraday there are about seventy lettersfrom him to Sch '

onbein,and as many more from Scho'nbein

in reply ; then come Grove, Graham,Sir John Herschel,

and a series of other English men of science . AmongGermans there is in the first place Wilhelm Eisenlohr ofKarlsruhe, the physicist, who furnishes more than a

hundred letters 3 then Schelling, Schonbein’s great teacher,

with whom he kept up a steady intercourse until hisdeath ; Liebig with fifty letters

,and Pettenkofer with as

many more,and Wo

'

hler with about thirty thenMartins,

Jolly, Kobell, Steinheil ofMunich, Magnus,Mitscherlich,

and Peggendorfi'

of Berlin,Erdmann of Leipsic, Muneke

of Heidelberg, Hugo Mohl of Tubingen,D ingler of

Augsburg,the well-known editor of the Polytechnical

Journal,in whose factory young Sch '

o’

nbein had onceworked

,and many others, particularly among his Swabian

countrymen. To these must be added a series of Swissscientific men : Auguste de la Rive , Marignac

,Brunner,

and Agassiz ; while among Frenchmen we have HenriSa inte-Claire-D eville

, Dumas, Sooutetten of Metz,etc .

Finally there are nine letters extending from 1837’

to

1847 from Jakob Berzelius .The 9th of August of this year [1898] was the fiftieth

anniversary of the death of Berzelius, who was exactlytwenty years older than Scho'nbein

,and died twenty years

before him. This anniversary, as is right,is not to be

allowed to pass unnoticed it is to be celebrated in Stockholm on the 9th of O ctober

, and I should be glad to beable to assist in the celebration in some slight degree, by'

laying the following pages as a modest tribute on the tombof the great master.

7

Prof. Henrik G . Soderbaum of Stockholm, a Fellow of

the . Royal Swedish Academy of Sciences, has alreadypublished at my suggestion, in the series of Monographs

on the History of Chemishy which I am editing, a

number dedicated to the memory of Berzelius, a subjectwith which he is peculiarly fitted to deal ; but I shouldwish to contribute my mite personally, by giving to thepublic on the day of the celebration in Stockholm the

correspondence between Berzelius and Sch '

o'

nbein whichhas been placed in my hands.

Wnat I have to offer contains no startling noveltiesno explanations that are to revolutionize our previoustheories can be derived from these lette rs . But to provewhat I have said of the importance of letters as the

original sources of the history of the development of

certain definite ideas, and of‘

the knowledge of personalitieswhich we can derive from them, it is only necessary tocompare the letters which Berzelius wrote to Scho‘nbeinwith those which he wrote to Liebig 3 for even these fewpages substantiate to the fullest extent the claims whichI have put forward .

And yet how wholly different were the lines of researchwhich the two men followed . Berzelius, a master of themethods of quantitative analysis

,has his attention always

centred on the finalproduct,considered in its quantitative

relations : Scho'nbein,for whom this branch of chemical

research possesses hardly any interest, is far more bent onacquiring from characteristic indications the means of

disentangling the course of the reactions . While Ber

zelius’mind embraced the whole range of chemical know

ledge,Scho'nbein concentrated his attention on a narrowly

contracted field, but yet regarded that field from com

manding points of view and both took an equal interestin observing the interconnection of chemical and electricalenergy. The younger man from the beginning looked up

8 PREFA CE

with honest reverence to his great master in Stockholm,

while the latter, gradually convinced O f the peculiar giftsO f his junior

,ended by proclaiming with no uncertain

voice the importance of his investigations ; the one,to

use Sch '

o’

nbein’s own words, with his ten talents gainingten more

,while the other none the less strove to put his

single talent out at usury.

” These two men have filledmany a page in the history O f our science

,often with im

perishable writings,and to these their letters serve as a

commentary . And I am grateful in no small degree to theRoyal Swedish Academy O f Sciences at Stockholm

,and to

their permanent secretary,Prof. G. Lindhagen, for their

great kindness and liberality in handing over to me forpublication the letters of Scho’nbein to Berzelius

,which

are in the possession of the Academy,to which the letters

of Berzelius always have immediate reference . I wasthus enabled to do what is seldom possible in such a case

,

namely,to give both sides O f the correspondence at

once.

I trust that this little book will be favourably received ;but at all events the two men whose words it containswill secure for it a hearing.

GEORG W. A . KAHLBAUM.

STEINABAD,BLACK FO REST ,

lst September 1898.

NOTE B" THE TRANSLATORS.

WE have included in this translation two letters O f

Scho’nbein’s (O f 12th February and 29th Marchand also a paper O f Scho’nbein’s

,

“ O n various chemicalstates of oxygen, ” which are not in the German edition .

They were discovered in January 1899 (after the latterhad been published), together with about 200 otherletters addressed to Berzelius, in the Berzelius Museumat Stockholm, by Herr Lindstrom . They were placedin the University Library at Bale for a time

,in order

that we might O btain copies O f them,and we wish to

express our thanks to the authorities O f the Libraryfor their kindn ess in permitting us to do so. Sch '

o'

n

bein’s paper,which has never before appeared in print

,

is O f interest both generally and as thr owing light on

the views which he expresses in his letters to Berzelius .

I I .

I I I .

IV .

V I.

V II.

V I I I .

IX.

XI .

XII .

X I I I .

XIV .

XV .

C O N T E N T S .

Editor’s Preface,

Note by the Translators,

Schonbein to Berzelius, 22nd April 1836 ,

Berzelius to Schonbein, 4th May 1837,

Schonbein to Berzelius, 14th O ctober 1838,

Berzelius to Schonbein, 13th November 1838,

Schonbein to Berzelius, 28th March 1839 ,

Berzelius to Schonbein, 18th September 1840 ,

Schonbein to Berzelius, 11th September 1840,

Berzelius to Schonbein, 3rd November 1840 ,

Schonbein to Berzelius, 23rd February 1844,

Schonbein to Berzelius, 14th April 1844,

Berzelius to Sch '

onbein,l6th May 1844,

Schonbein to Berzelius, 15th January 1845 ,

Berzelius to Schonbein, 14th February 1845 ,

Schonbein to Berzelius, lst March 1845 ,

Sch'

Onbein to Berzelius, 22md March 1845 ,

12 CONTENTS

XV I. Schonbein to Berzelius, 3oth September 1845 ,

XV I I . Schonbein to Berzelius, 5th March 1846,

XV II I .

XIX.

XX.

XXI .

XXI I .

Schonbein to Berzelius, 2oth June 1846,

Berzelius to Schonbein, 18th November 1846,

Schonbein to Berzelius, 12th February 1847,

Berzelius to Schonbein, 12th March 1847,

Schonbein to Berzelius, 29th March 1847,

Appendix. O n various chemical states of oxygen,

O F T HE

“NfVERs rrv

THE LETTERS OF

BERZELIUS AND SCHONBEIN

S OHO NBE IN spent the winter O f 1827 -28 in Paris, whitherhe had gone like so many men of various nationalitiesat that time to complete his studies . He had been a

science master in a school at Epsom and had acquireda thorough knowledge of English. About this time a

French edition of Berzelius’ Larbok z’

Keme'

en was published . In an undated letter which I have before mein draft only

,but which was probably written in

November 1827, Scho’

nbein writes to Koller, a friend

and countryman of his,who was a bookseller in London

,

as follows : “ Now as to a proposal which I'

have no

doubt you will accept. "ou are probably aware thatamong chemists Berzelius is one O f the leading lights O fthe age, and that his textbook O f chemistry

,which

,how

ever,will not be completed before next year, is a classical

work. Three volumes have already appeared the fourthand concluding one is expected soon. Now Englandactually does not at present possess such a book ; and

since Berzelius is undoubtedly held in great esteem in

this country and his book is superior to any in Europein originality and exhaustive treatment of its subject, a

14 LETTERS OF BERZELIUS

friend O f mine, an English chemist here,and I

,thought

it would be well worth our while to undertake a transla

tion O f it into English. We are quite convinced thatsuch a publication would prove a financial success to thepublisher. Therefore I O ffer you the translation

,and in

the event O f your accepting it I enclose a brief announcement which I think it would be desirable to print in somewidely-read paper

,for the purpose of keeping others

from a similar undertaking and also of bringing it underthe notice O f the public . Please let me know your finaldecision by return O fpost, for , sh ould youn ot feel inclin edto undertake it

,we shall have to turn elsewhere . It is

no doubt an immense task,but by no means a hazardous

one , and certainly more profitable than the booksellingbusiness.

“My time is at present so taken up‘ that I must

content myself with sending you my kindest regards.—C. F . S .

”

That Schonbe in was really in earnest in his intentionof translating Berzelius’ b ook into English is shown bythe fact that he enclosed an announcement of the proposedtranslation for the daily papers.We can also see what special Object S chonbein had

in approaching so great a task . Sprung from humblesurroundings

,he was forced to gain his own

"

livelihoodand in addition to the strong liking he then had for

teaching, for'

which,however

,he failed .to find apromismg

field in P aris,he devoted himself k eenly to literary

pursuits . Thus, in N ovember 1827, almost at the timewhen he formed the project O f translating Berzelius, hewrote to Friedrich

'

Perthes of Gotha, with whom he wasalready acquainted through his son and nephew,

O fferingto tranSlate into German

,from his shorthand notes, the

lectures on physics g iven by G ay-Lussac at the Sorbonne ,and to entrust them to him for publication. But this

AND SOHONREIN 15

and other 'works were comparatively unimportant enterprises, whereas the translating O f the s olid 200 sheets ofBerzelius’ treatise

,a nd moreover into English, a foreign

language,was certainly a stupendous task .

The motives which induced him to undertake s o greata work we learn from a letter

,which I ‘

possess only as anundated draft

,which he wrote at about this time to his

friend and countryman Heldenmeier,who also was a

schoolmaster at Epsom. In this letter he declines forthe time be ing an O ffer to assist in founding a school inhis “ be loved Switzerland,” "

and w rite s re specting it as

follows “ Let me tell you why four weeks ago I formeda fixed determination of [going] to Berzelius at Stockholmtowards the end O f next [year 2] to c omplete my studie sunder this consummate master of chemical science ; thisplan leads to othe rs means must be procured for its realization and it is a translation of Berzelius’unique workthat is to procure them a part O f this work has alreadyappeared and the remainder

.

is still in the press . Withthis end in view I have joined with a young Englishman

,

with whom I shall soon enter upon the work , which willoccupy us six months at the very least. S O far w e knowO f no publisher

,but we do not doubt that we shall be

able to find one,for the publication cannot be otherwise

than lucrative . Le t this,however

,remain a secret

between us . I do not intend to return to England be forethe lectures are over, for this would be foolish . N or

shall I stay long. Should our plans b e r ealized I sh allsoon be sailing towards Sweden

,where I propo se to spend

at least '

six months . But after thatNothing “came of the translation of G ay

-Lussac’s

lectures for Perthes wrote on D ecember the lst declining,though in the most courteous terms

,to publish them ,

owing to other more pressing business,the details of

which he specifies a similar fate befel the English


translation O f Berzelius’ textbook. The publisher couldnot persuade himself to undertake the work, which,though attended with a considerable outlay

,would uh

questionably have resulted in pecuniary gain. The

consequence was that England had to dispense with a

translation O f Berzelius’ great and at that time unsurpassedwork, while Sch

'

o'

nbein,foiled in his plan for obtaining

the necessary supplies,had to relinquish his scheme O f

concluding his studies under “ the consummate masterO f chemical science .

”

It is no doubt an idle task to imagine what might havehappened if matters had fallen out otherwise ; but wecannot resist a feeling O f the keenest regret that it wasnot granted to Sch '

onbein to turn his attention to quantitative work as we ll under the influence of the powerfulpersonality of Berzelius

,and our disappointment that a

publisher’s lack of public spirit should have preventedS cho’nbein from making this pilgrimage

,is even more

acute than that caused by the events which hinderedLiebig from working under this great Chemist’s direction .

Berzelius and Schonbein were so unlike in character thatthey could not but have been drawn together ; and

Schonbein would have supplemented Berzelius far morefully than Liebig would have done . O nce again we

come across the name O f Berzelius about this time in a

manuscript of Scho'nbein’s . A small diary begun on the

2 1st of January 1828 in Paris,the last entry of which

dates from the l0th O f March,gives us a clue to the

reading to which Sch '

onbein devoted himself at this period .

A large part of this book,

fifteen pages out O f thirty,is occupied by an abstract O f Berzelius’ paper on indigo .

1

It is evident therefore that Scho’nbein was not thenpenetrated “ by that almost unconquerable aversion to

1 “ Recherches sur l’Indigo,” Annal. de Chimie, vol. xxxvi.(1827) pp. 310 and 350 .

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teristie O f Schonbe in that the report in the transactionsis not written by himself

,but by his countryman and

friend Fischer,1 professor O f philosophy,in a paper

occupying twenty-six . pages,ent itled “ A ccount Of. Pro

fessor Sch '

onbein’s experiments on the behaviour of. irontowards oxygen .

” 2

I t is these experiments which form the subj ect O f

S cho'nbein’s first letter to Berzelius, dat ed 22nd of April 135,

1836. The letter is as follows

S chonbein to Berzelius

Ram,22nd April 1836 .

DEAR SIR,

It is only your well-known kindness,and a

hope which I entertain. that what I have to com

municate may not be who lly without interest to you,

which encourage me, though a perfect stranger, totrouble you with a

“ letter from SO great a distance.

For several months I have been occupied with themore accurate determination of the behaviour O f

certain metals, particularly iron , under various con.

ditions, in the presence O f nitric acid. My “ work has

p . 444 ; [vol. xxxix. p. 137] Bibl. unin , vol. i1i. p .

387 vol. v . p . 177 Phil. Mag ., vol. ix. pp . 53 and [25 9]The passages in brackets were printed after the Bale

Report.1 Friedrich Fischer, professor of philosophy at Bails from

1832 to 1853, born in 1801 at Honau,Black Forest

, in

Win temberg, and d ied in 1853 at Winnenden in the Neckardistrict.

2 Basler Bericht, vol. i. , part 2 p. 72 .

AND SrCHONBEIN.

~ 9

not been altogether. without results. I have observedcertain new phenomena which can hardly fail

,

especially from an . electro-chemical point of view ,to

attract the attent ion of scientific chemists. They areessentially as follows : If the end of. an ordinaryiron wire O f any size is heated in a spirit lamp untilits surface has become blue , and is then put in nitricacid O f specific gravity about 13 5 , ne ither. the heatednor the other end of the wire is. attacked . Indeed ,the acid can be heated almost to its boiling poin tbefore it acts on the metal , although it attacksordinary iron even when cold. A similar behaviouris shown by iron filings which have been heated on lyfor a few se conds , that is, until they have assumed ablue colour. Now it is remarkable that the protective power Of. the heated end seems to extend through .

any length O f wire , however grea t . I took a wire50 feet long and a line thick

,heated one end for a

distance of not more than a . few lines, and put firstthis end and then the. other into acid of the abovementioned strength. Under these cir cumstances nopart of the wire was attacked

,even when its whole

length was allowed to lie in the acid. In order toobtain a reaction it was necessary to heat the liquidat least to I performed similar experimentswith iron rods O f a considerable size

,and always .

O btained the same result. Another remarkable factis this : An iron wire which has thus been protectedagainst the ac tion of nitric acid can bring anotheriron wire into the same neutral condition merely bycOntact (which need only last for a moment

,below

20 LETTERS O F BERZELIUS

the surface of the liquid). TO convince yourself ofthis extraordinary phenomenon , take an iron wire ,O ne end O f which has been tempered by heating.

Bring the unheated end into close contact with one

end O f another ordinary iron wire . If you now putfirst the heated end O f the first wire and then the

o ther end of the second wire into the acid,the latter

will not be attacked by it, even if the contact betweenthe two wires is destroyed. The second wire, havingthus become passive , can communicate the conditionto a third

,and this to a fourth

,and so on

,provided

that the wires are brought into contact within the

liquid in the manner described . In order to preventany misunderstanding as to this second method O f

rendering an iron wire inactive, I give a detailedaccount O f the way in which the experiment is to becarried out. The ordinary wire , which has thus beenmade indifferent to nitric acid

,and which for the ~

sake O f simplicity I will call secondarily indifferent,

”

is taken out of the acid,and

,at any point which has

not been immersed, brought into contact with anotheriron wire. The end O f the secondarily indifferentwire is then placed in the acid ; and finally the endO f the other wire. Both wires now remain passive inthe liquid

,always supposing that the temperature

does not rise above For the sake of completeness I must add that an iron wire which has beenimmersed in nitric acid of Specific gravity 15 is likewise indifferent to the acid O f Specific gravity 13 6.

A third phenomenon O f interest is this : if an ironwire

,which has been made indifferent to nitric acid

AND SOHONREIN 21

in any O f the ways described , is placed in the acid , itis again attacked by it if brought into contact withanymetal , even iron itself, which is actually beingdissolved by the acid. The indifferent wire can ,

how

ever,be made active even if the part projecting above

the liquid (which may be O f any desired length) isbrought into contact with the similarly projectingpart of the active wire . For example in the aecompanying figure

1 let a b be the vessel containing thenitric acid

,0 d the indifferent , and ef the active wire.

If now the point e of the wire 0 d is brought intocontact with the point e O f e f , the immersed portionof e d at once becomes active , as also happens if ftouches d . The same thing occurs likewise if c isconnected with d by anymetallic wire .

If the nitric acid is very dilute none of thesephenomena happen. After arriving at these resul tsI was curious to see how an iron wire would behavein nitric acid if it was made the positive pole of avol taic circuit . My experiments on this point haveled to the following results. If the negative pole O fa cup apparatus of fifteen elements is connected withnitric acid O f specific gravity by means O f apla tinum wire

,and one end O f a common iron wire

,

of which the other is attached to the positive pole , isplunged in the acid

,this wire remains perfectly in

active and possesses generally all the properties of

the wires O f which I have Spoken above . Thus awire O f this kind when separated from the positivepole is not attacked by ordinary nitric acid. But if

1 There is no figure in the letter .


the circuit is not closed exactly in the order I havedescribed

,the nitric acid acts on the wire in the

usual chemical manner. If an iron wire which hasin any way been made indifferen t is connected withthe negative pole of a battery, it is instantly attackedby the acid with violence. But the most remarkablefact O f all , a fact which no one , so far as I know, hasever Observed , is this . The positive iron wire is notonly noL astsd e n

—byL the acid

,but it is not even

oxidized by the oxygen which 18 set freeat its surfaceby the decomposition of the water, which shouldoccur according to the accepted theory . The oxygenappears as a gas on the iron just as it does on a wireO f silver or platinum

,and the metallic surface is not

altered in the smallest degree. This liberation of

oxygen on the iron wire occurs in the most dilute as

well as in concentrated nitric acid , if, as I must oncemore repeat, the circuit is closed exactly in the orderI have described . If you employ an acid O f specificgravity diluted with ten times its volume of

water , and close the circuit, for example,with the

negative pole,not the smallest bubble O f oxygen

appears on the iron wire forming the positive pole ;on the contrary an iron salt is produced which sinksdown in yellowish-brown streams. The same occurseven in acid diluted with 400 times its volume O f

water . But if the end O f the iron wire which hasbeen plunged in the acid is held only for a fewseconds in the air, and then the circuit is closed withit, the oxygen again appears on its surface in the

gaseous form . If the iron terminal from which

AND SOHONREIN 23

oxygen is coming OH" is made to touch the negative

pole within the liquid for a few moments,the oxygen

no longer appears on its surface even when the twowires are separated, the nitrate being produced instead ; but in this case also the iron resumes itsformer indifference to the oxygen if it is he ld in theair. I have measured the quantities O f the gasesdeveloped in the same time at the two poles andfound that the volume O f the oxygen collected at thepositive iron electrode bears to that of the hydrogenproduced at the negative pole the ratio whichmay serve as a further proof that under these conditions the iron is not in the least oxidized . Ironplaced under the same conditions in water to whichsulphuric or phosphoric acid has been added

,likewise

develops oxygen gas ; but if the metal has previouslybeen placed in water containing sulphuric acid

,or if

the circuit is closed with the negative pole,this

phenomenon does not occur. If the pole wires fromwhich the gases are coming off are made to touch fora moment within the liquid , then,

after they are

separated, no further development of oxygen takesplace

,even if the iron wire is held for some tM e in

the air. In water containing potash, the oxygen

always appears in the free state on the iron, in what

ever manner the circuit is closed . It is hardlynecessary to say that the iron must be the positivepole . In order to bring to a conclusion a letterwhich is already too long, I shall stop here and takethe liberty O f drawing your attention to some papersO f mine , in which the phenomena I have described


are treated in more detail , and which I hope willsoon appear in Poggendorf s Annalen . These phenomena seem to me to be of the more importance inthat they do not agree ‘with the electro-chemicaltheory which is at present accepted . "ou havealready thrown light on so many of the dark placesof chemistry that I have no doubt ‘

you will also beable to give a satisfactory solution of the problemwhich my O bservations present.Finally

,I would once more ask you to pardon the

liberty I have t aken ; and I beg to subscribe myselfwith the utmost respect and esteem ,

Your obedient servant,

Dr. SC ONBEIN,

Professor of C hemistry.

Berzelius answered in the following letter, which reachedBails on the 15 th of May 1837

B erzelius to S chonbein

STO OKHO LM, 4th May 1837.

DEAR SIR,

There is an old proverb : Quad difertar ,anfertnr . This might well be applied to my answerto the letter with which you favoured me on 22nd

April 1836, and in which you communicated to meyour observations on the peculiar behaviour of ironin the presence of nitric acid. I was away when the


tion,of passing from an electro-positive to an electro

negative state , and remaining in this state undersuitable conditions, thus changing from an oxidizableto a noble metal. If we admit this

,the question

arises, What are the means by which this new

electrical state is produced 7 Your experimentsindicate two distinct methods by which it can be

effected : in the first place by communicating to theiron the electrical condition of some other body , forexample platinum ,

gold,concentrated nitric acid

,

possibly also ferric oxide , and in the next place bymeans of contact e lectricity

,whereby a body with a

strong positive charge , such as the positive pole of

a battery or a solution of an alkaline hydrate , produces in the iron a charge O f the opposite character.But of course you cannot admit the latter assumption ,

since you accept de la Rive’s V iew that electricity O f

an opposite character cannot be produced by contact.1

In this,however

,I do not agree with you ; I am

firmly convinced that when we understand the causeO f this remarkable property O f iron we shall find init one more proof that Volta’s conception was moreprofound and nearer the truth than that of hisopponents

,who

,by admitting that electricity and

chemical a "

1nity are different manifestations of thesame force, acknowledge, though without being con

scious of so doing,that Volta was right.

In the O lder papers 2 on the subject,ammonia also

1 Cf. Berzelius, Jahresbericht. Translated byWohler. V ol.

xvn . (1838) pp . 32 and 116.

2 Keir, Phil. Trans. (1790) p . 359 ; Wetzlar, Sch/weigger

AND SOHONREIN 27

is said to have the power of bringing iron into thiscondition. It would be wel l worth while investigatingto what extent the other two magnetic metals ,nickel and cobalt

,have this property ; even if they do

not possess it to the same degree, they may showsome indications of its exis tence.

1

I hope you do not intend to abandon this workjust yet ; it is conceivable that you may be able todiscover a method for making iron in any quantityretain

.

this condition for any length of time : sucha discovery would be of the highest value.

I have the honour to remain,

With the profoundest respect,

Yours O bediently,JAO . BERZELIUS .

In a letter, written in French, of the 12 th of January1838

,Berzelius as permanent secretary of the Academy

acknowledges the receipt of the paper entitled : “ The

behaviour of iron towards oxygen, ” 2 and to the printedform adds a few words of thanks on his own behalf forthe copy sent to him personally.

The letter,however, contains nothing worth reprinting.

Jahrb. , vol. xix. (1827) p . 470 vol. xx. (1827) pp . 88 and 129

vol. xxv. (1829) p . 206 Fechner, ibid . , vol. xxii . (1828) p . 27

vol. xxiii . (1828) pp . 61, 129 and 429 vol. xxv. (1829) p ,223

Fischer,o

Poggend . Annalq vol. vi . (1826) p. 43 ; Herschel, ibid.,

vol. xxxi i . (1834) p . 211 , .cf also Mousson,ibid. , vol. xxxix.

(1836) p. 330 .

1 Of. Schonbein, Phil. Mag . vol. xi . (1837) p. 544 and

Poggend. Annals vol. xliii. (1838) p . 18.

2 DasVerhalten des Eisens zumSauerstoff. EinBeitrag zurErweiterung electro chemischer Kenntnisse . V on Dr. L. [ l] F.

S chOnbein, Professor der Chemie in Basel. Basel, 1837.


O n O ctober 14th of the same year, Schonbein again

writes to Berzelius . to report on his latest electro chemicalinvestigations.

S chonbein to B erze lius

DEAR SIR,

I trust you will forgive me for again takingthe liberty O f troubling you with a letter , as it is onlyscientific motives which induce me to write . In thelast few months I have spent a considerable timeon voltaic investigations , and have arrived at someconclusions which seem to me not without importancefor electro-chemistry, and which I think you will beinterested to hear.Becquerel asserts in his Traite that wires forming

the poles of a circuit possess the power of pro

ducing a secondary current only when they are in a

saline solution ,and his view is that this current is

due to the re combination , under suitable circumstances , O i the base and the acid which have beenseparated at the poles. The results of my latestexperiments render this theory untenable

,for the

following reasons1. Chemically pure hydrochloric acid , sulphuric

acid,potash solution

,etc.

,when used to complete the

circuit admit Of electrical polarization of the electrodes just as much as saline solutions .2 . Polarization O f the electrodes occurs also when

the battery current which traverses them is too feeble

AND SCHONBEIN 29

to effect electrolysis, when , for example, it cannotdecompose potassium iodide.

There is,however, another fact that I have dis

covered, which I wish particularly to recommend toyour attention

,and it “

is one which I think can

hardly fail to excite the interest of chemist andphysicist alike. It is the capacity which everycompound liquid conductor (electrolyte) possesses ofbecoming electrical ly polarized.

The following facts will serve to bear out myassertion. Fill a U-shaped tube with chemicallypure hydrochloric acid ; put a platinum wire intoeach limb

,and connect these wires for. a few seconds

with the poles of a battery whose current is toofeeble to produce on the electrodes the smallest traceO f gas. Now remove the wires from the tube, andreplace them by another pair of platinum wires whichhave not been subjected to the action of a current ;finally , connect these wires with a galvanometer ofseveral thousand turns . Under these circumstancesthe needle of the galvanometer will be deflected insuch a direction as to indicate a current flowing fromthe limb into which the negative e lectrode dipped tothat which was connected with the positive pole ; inother words

,the former limb of the tube behaves as

if it were positive to the latter. This fact makes itO bvious that the e lectrode and the column of liquid

In contact with it are both electricallypolarized at the same time and in the same sense bythe current which traverses them . As my work on

this subject will soon be published in Poggendorfi’

s


A nnalen,

1 I wil l not enter into any further particularshere , but will only say a few words on the apparentcause of the polarization of liquids.Since neither the voltaic nor the ordinary chemical

theory of galvanism is able to explain this strangephenomenon

,I have endeavoured to account for it

in the following manner. A current which is toofeeble to be able to decompose the hydrochloric acidthrough which it passes still exerts some influenceupon it . In the first place it dim inishes the mutualaffinity O f the component parts O f each molecule of

acid,though without actually separating them ; and

in the second place,such a current arranges all the

acid molecules so that their hydr ogen is directedtowards the negative and their chlorine towards thepositive pole . Now

,if we assume further that in

consequence of a certain inertia of the atoms thiscondition of the acid does not disappear at once whenthe current is interrupted, but that the constituentparts of each molecule return only by degrees totheir previous condition of intimate connection , thenthis act of re combination of the hydrogen and chlorinenecessarily must

,in accordance with the funda

mental laws of electro-chemistry , produce a currentof exactly the kind which I have O bserved. That isto say

,the liquid column which was connected with

the negative pole must be positive to that which wasconnected with the positive pole ; and this conditionof electrical polarization must continue until theo riginal equilibrium between the hydrogen and

1 Poggend. Annal., vol. xlvi . (1839) p ,109 .

AND SOHONREIN 31

chlorine atoms has been restored throughout thewhole system of mo lecules . Now experiment hasshown that the current produced by the polarized aciddoes as a fact last for a considerable time, as you willfind stated in the paper to which I have referred.

If my hypothesis ascribes the polarization in

question to its true cause, it must lead to the important conclusion for theoretical chemistry that betweenthe complete separation of two elements and theirmost intimate chemical union there exist intermediateconditions of combination

,of which as yet we know

nothing ; unless indeed isomerism points to some suchrelation . A s you may readily conceive , I shalldevote my whole attention to a subject of such greattheoretical interest

,and shall endeavour by pursuing

my investigations to throw still more light on the

question. If it were not too much presumption on

my part I would ask you to be so kind as to com

municate to me at your leisure your views as to thecause of the electrical polarization of liquid electrolytes. To a student O f chemistry any suggestionfrom so practised a master would be a cause of

gratification and encouragement.In conclusion

,I should be much obliged if you

would tell me whether the Royal A cademy of

Stockholm rece ives papers in German , and, if so,

what formalities have to be O bserved .

I have the honour to remain,dear Sir

,

Your most obedient servant ,C . F . SOHONBEIN.

BALE,14th O ctober 1838.


In a comparatively short time, that is to say in lessthan a month, Schonbein received the following reply,which reached Bide on the 25th of November.

Berzelius to S chOnbein

STO CKHO LM,13th November 1838.

DEAR SIR,

I am greatly indebted to you for yourinteresting communication of 14th O ctober .The polarization observed in the case of the SO

called liquid conductors is an experimental proof ofan assumption which

,in my opmlon,

1s quite essential to the theory of the electrical . battery. I amconfident that it may be taken as proved beyonda doubt . that all substances

,from the metals to the

worst conductors, as glass and resin , are capable O f

assuming electric polarity,which will have a greater

tension and last the longer the greater theirresistance . This

.polarity is produced by every

disturbance of electric equilibrium ,but the less

resistance a body has,the more rapidly does it dis

appear , and the less is its tension Hence the greatdi iculty of actually exhibiting it in the case Of goodconductors. But it is precisely this property of aliquid or , moist conductor on which the phenomenaof a hydro-electric pile depend, whether the initialdestruction of electrical equilibrium is due to contactelectricity or to chemical action and without it the


more than in the resinous disk of the electrophorus ,which can receive a higher charge and retain it fora very long time ; in fact, the power of becomingpolarized must be a fundamental property of allbodies .I have read with the greatest interest the papers

you published in Poggendorfi’

s A nnalen and in the

English Journals , and can only urge you to followup this important investigation .

With the profoundest respect,

Dear Sir,

Yours very truly,JAO . BERZELIUS .


DEAR SIR,

I have taken the liberty of sending you the

last number of the Transactions of the SwissAssociation for the Advancement of Science , witha humble request that you will give it a kindlyreception.

Though it does not contain much of great interest,

you will perhaps gather from it that the Swisshave at least the wish to enlarge the boundary of

science.

The accompanying three numbers of the Report ofthe work of the Scientific Club of this town are

intended for the Royal A cademy, and as President of

AND SOHONBEIN 35

that Club I request you to be so good as to forwardthem to their destination .

I thank you most sincerely for your kindness inanswering the letter in which I had the honour toinform you of my O bservations on the po larization O f

water and other e lectrolytic liquids . In the courseof the last few months I have instituted a largenumber of new experiments on this subject

,and

have arrived at results which in my opinion givea satisfactory explanation of the phenomenon. In

a paper which will , I hOpe , soon be published inPoggendorfi

’

s Annalen,

1 I have described part of myobservations and have endeavoured to Show thatelectrolytic liquids are not capable of voltaic polarization in the proper sense

,and that the current which

is produced by the so-called polarized bodies is dueto chemical action . I rely chiefly on the followmgfacts to prove the correctness of this view. An

aqueous solution of hydrogen (containing somesulphuric acid to make it a better conductor) bearsthe same electrical relation to an aqueous so lution of

oxygen (also containing sulphuric acid), that theliquid (water acidified with sulphuric acid) in one

limb O f a U-tnbe,in which the negative pole of a

battery has been placed bears to the same liquid inthe other limb connected with the positive pole.

The two latter liquids only show themselves polarizedafter the current has traversed them

,if they are

connected with the circuit by means of platinumwires and not if wires of gold or silver are employed.

1 Poggend. Annal., vol. xlvii . (1839) p . 10 1.


This is exactly the behaviour of the two liquids firs tmentioned

,a solution of hydrogen and a solution of

oxygen or of ordinary atmospheric air. If the waterhad been actually polarized by the current from thebattery

,one would of course get a secondary current

whether the wires used to close the circuit were of

gold or platinum . I have given a detailed accountof this subject in several journals

,

1 which you willdoubtless soon receive

,and so it is unnecessary for

me to enter into particulars here ; but I cannotrefrain from making the general remark that myinvestigations appear to Show that the act of

chemical combination of the elements is not due tothe play of electrical forces

,or

,in other words, that

a“ '

inity and electricity are not the same thing,

though they are mutually dependent . I am intending soon to develop these views of mine in a separatetreatise , and to establish their truth on experimentalgrounds.If I venture to express a doubt as to the truth of

the electro-chemical theory , it is in the convictionthat its founder would be the last man to blame mefor so doing

,and I am sure that you will weigh the

arguments which I have to br ing against it in a

Spirit O f the most perfect impartiality . "ou are too

much inspired by a pure love of science , and youtake too high a position in the scientific world , forsubordinate considerations to exercise any influenceon your judgment .2

1 Journalfur praht. Chemie, vol. xx . (1840) p. 129 [l] .2 Of. Poggend. A nnal., vol. xlvi. (1839) p . 336 .

AND SOHONREIN 37

I trust you will pardon my writing to you

often,and with the greatest respectI have the honour to be ,

Dear Sir,Your most obedient servant ,

C . F . SOHONBEIN.

BALE, 28th March 1839 .

Berzelius replied somewhat briefly to this letter. If,in

fact, though I amnot quite certain about it,the passage

in Scho’nbein’s letter refers to his brief summary in vol.

xx. of the Journal fur praktische Chemie, which however was not printed till 1840 , he rej ects Scho

'

nbein’sinterpretation with the following curt and severe comment“Even these outlines show that Scho’nbein has not

grasped the spirit of the electro chemical theory.

” 1 I

imagine that the following letter of Berzelius relates tothis paper of Scho’nbein’s

,because in the Jahresbericht,

vol. xxi . , it is discussed simultaneously with the paper O fFaraday

’

s mentioned below.

Berzelius to S chonbein

STO OKHO LM,18th S eptember 1840

The permanent secretary of the A cademy to

Professor Schonbein , BAle.

The Academy has received your three treatises ,entitled

,

“Bericht uber die Verhandlungen der

1 Jah/resberieht, vol. xxi . (1842) p . 33 .


Naturforschenden Gesellschaft in Basel, also, “ Mittelund Hauptresultate ans meteorologischen Beobachtungen in Basel,

” by Peter Merian,which you were

kind enough to send to it . I am instructed to

express to you their gratitude . The papers havebeen deposited in the library of the Academy . Withthe assurance of my utmost regard ,

I have the honour, Sir, to remain,

Your very humble servant,

JAc. BERZELIUS .

P .S .—I must thank you on my own behalf for the

number of the Transactions of the Swiss Associationfor the A dvancement of Science of their meeting atBade in 1838 , which you were kind enough to sendme , and also for the very friendly letter, in which

you stated the reasons which induced you to ascribehydroelectric phenomena to the play O f chemicalaffinities . This is also the opinion which Mr. Faradayarrived at after his long series of researches on thesubject 1 ; and it certainly is the O pinion whichsuggests itself at first sight . I dare say you are

aware that I do not adhere to it , and I am alwayswaiting for some of

"

the physicists who hold the socalled chemical theory to explain by this hypothesisin a satisfactory manner the chemical phenomenabrought about by the electric current, as for examplethe reduction of potash ; for a theory which failsto give any distinct or logical explanation of the

chemical decompositions produced by the electrical1 Phil. Mag. ,

i . 16 (1840) p. 336.

AND SCHONBEIN 39

current cannot be the true theory of the electricbattery or O f the cause which renders it active. O n

the other hand the contact theory , according to whichchemical affinities depend on the electrical state andnot nice oersd , adequately explain the chemicalphenomena which the battery produces.

S chonbe in to Berzelius

DEAR SIR,

I take the liberty O f sending you,by favour

of Herr Schiitz of Summiswald,a paper 1 which you

have probably not yet seen ,and whose contents will

,

I think, not be wholly without interest to you.

Unfortunately,the accumulation of business has

prevented me from fo llowing up further the subjectwhich is there discussed ; and I have not had timeto prepare the odoriferous principle (which I maymention that I have called ozone) in sufficientlylarge quantities to be able to determine its chemicalproperties accurately. As soon as I have the necessaryleisure I shall proceed at once to continue thiswork

,and shall in due time make the scientific

1 The reference isprobably to the paper : Beobachtungen uberden bei der Electrolysation des Wassers nnd dem AusstrO

’

men

der get nlichen Elektricitat ans Spitzen sich entwickelndenG erno Wh ich edition is meant, whether A bhandl. der

Munchner A kademie, iii. 257, or Poggendorfl'

,50 , 616, I cannot

say. In the Jahresbericht,xxi. (1842) p. 39 , Berzelius refers to

the Annalen.


public acquainted with the results of my investigations.Meanwhile I have practically proved that ozone

plays an important part in the so-called voltaicpolarization of water , and that it is the cause

,for

example , of the negativity of that portion O f . the

acidified water in which the positive pole of a batteryhas been placed.

I Should be excessively obliged if you would takean opportunity of letting me know what you thinkof the conclusions which I have drawn from myexperiments .Is it not possible that we might sometime have

the honour and pleasure of welcoming you in

Switzerland ? I do not think you would find our

country otherwise than agreeable . I have for a

long time had a great desire to see your interestingcountry

,but 1 having got a wife and near ly half a

dozen of children I am nailed down to a spot andcannot think of moving much about .With the greatest respect , I have the honour to be ,

Dear Sir,

Your most obedient servant ,C . F . SOHONREIN.

BALE, 11th September 1840 .

I do not possess the original of Berzelius’ answer to thisletter, in which Schonbein gave the first information of the

discovery of ozone,but only a copy (expressly described

as such) in Sch'

onbein’s own hand. In April ‘

1840

1[The rest of this sentence is in English in the original.

—Tr. ]


drop,and I also shall not fail, whenever I have a con

venient opportunity, to remind him of it. I regret tosay, however, that the Prince has taken all the documentsand also your note to Berzelius along with him.

Sch '

o'

nbe in had in fact enclosed,as a recommendation ,

Berzelius’ letter to him on the discovery of ozone . PrinceMaximilian never returned it

,but Schonbein had prudently

retained a copy.

Berzelius to S chonbein 1

STO OKHO LM,3rd November 1840 .

DEAR SIR,

I thank you sincerely for your paper on‘

ozone ,and the courteous letter which accompanied it. Iread it with great interest , and consider it highlyprobable

,as you suggest, that natural waters con

tain,though in very minute quantities , some volatile

matter , composed possibly O f hydrogen and ozone .

The building up of this body in some conclusivemanner would be one of the most brilliant chemicaldiscoveries ever achieved by science . I need hardlyurge you not to let the matter drop before you are

successful,however great an exertion be required. I t

is quite probable that water is always accompaniedby this compound in nature

,for we know that common

salt never occurs in nature without traces of sodiumiodide or sodiumbromide .

1 This letter is mentioned in Hagenbach’s obituary notice of

SchOnbein. [Basel Universitdts-Progi'

anim,

AND SOHONREIN 43

In former times I noticed that whenever I performed electrical experiments for some time continuously, for which purpose I employed a very powerfulbattery

,the whole atmosphere of my room smelt of

phosphorus for hours afterwards. I was convincedthat this could not result from the action of electricityon the organs of smel l , since it continued even afterthe disengagement of electricity had ceased ; but itseemed impossible to determine how it originated .

I hope you will let me know what results you obtainby continuing these experiments.

With the greatest respect ,Yours most O bediently ,

JAc. BERZELIUS .


M" DEAR BARON,

I take the liberty of sending you a littlework 1 that has just appeared

,in which I have dis

cussed some physico-chemical questions . As you

will see from its contents,the views which I have

developed as to the relation between voltaism andchemism differ in important respects from those of

1 He refers to the book dated December 1843,and dedicated

to A . de la Rive, entitled, Beitra'

ge zur Physikalischen Chemie,Basel, 1844. It is divided into three parts : (1) O n the ire

quenoy of contact-action in chemistry. (2) O n the cause O f

increase of conductivity of water by means of acids, alkalis andsalts. (3) O n the action of hydro-electric currents.


Faraday and de la Rive ; but I hOpe that this willnot prevent my work from contributing somethingtowards the agreement of physicists on a questionwhich has so long been the subject of controversy.

In the second part of the book I have given someconjectures as tothe chemical constitution of the SO

called hydrated acids and bases,as well as of many

double salts . I am really very curious to hear what

you think of the hypotheses which I have propounded

,and you would be doing me the greatest

kindness if you would take an opportunity of lettingme know in a letter what is your frank opinion ofthem

,and also of the contents of the first section

,

dealing with contact action . I have been muchinterested to learn

,from a communication 1

of yoursto the Stockholm Academy, that you are inclined toascribe the passivity of iron to an allotropic condition of the metal . The only remarkable thing aboutit is that the allotropy should be confined to the

surface,and not extend in any degree to the interior

of the iron ; for the current which determines thepassivity of the surface

[

goes through every part ofthe iron

,which serves as positive electrode . The

statements which Martens of Brussels has quiterecently made to the A cademy of that town

,

2accord

ing to which a red heat , irrespective O f any oxidation ,

is su ” cient to secure the passivity of iron,are quite

‘

g

1 Stockholm A cadxHandl. (1843) p . 1 and Poggend. Annal. ,

vol. lxi. (1844) p . 14.

2 Bruxelles A cad . Sci. Bul. (1843) [Pt. 2] p ,406 [Supple

ment in Poggend. Annal , vol. lxi. (1844) p.

AND SCHONBEIN 45

without foundation,as I have convinced myself by

repeated experiments .With the greatest respect and esteem ,

I have the honour to be,my dear Baron ,

Yours most sincerely,

C . F . SCHO NBEIN .

BALE, 23rd February 1844.

Berzelius made no answer to this letter of Schonbein’s,nor does the Jahresbericht contain any references to thesequestions or to the book on physical chemistry forwardedto Be rzelius .

S chonbein to B e rze lius

BALE,14th April 1844.

M" DEAR BARON,

"ou were formerly interested in my experi

ments On the nature O f the electrical O dour,and so I

flatter myself that the results of my latest work 1 on

this subject will not be wholly indifferent to you,more

especially as they seemed to you to have opened anew field for chemical investigation . "ou will remember , no doubt, that I endeavoured to prove the

1 Lectures delivered at meetings of the Association for the

Advancement Of Science at Bdle on the 3rd and 17th of Apriland the 15 th ofMay1844 Basler B erichte

,vol. vi . (1844) p . 16 .

Bibl. Unin ,vol. 1. (1844) p . 395 ; collected in Uber die

Erzeugung des O zons auf chemischem Wege,” Basel, 1844. Pre

face dead 13th May 1844.


chemical identity of the substance produced by theelectrical discharge in the air and that formed in theelectrolysis of water from the similarity of theirvol taic properties ; and that the electric character ofmy ozone together with its chemical behaviour ledme to conjecture that it was a body very similar tochlorine. Q uite recently I have succeeded (at leastI think I have) not only in showing by a satisfactoryproof that the two odoriferous principles are identical

,

but also in preparing the substance by a chemicalmethod

,and that in such quantities that I have

every reason to hope that I shall be able to isolate it .The identity and the haloid character of the bodyproduced under such different conditions are shown1. By the complete similarity of the smell of chemical ,voltaic and electrical ozone. 2 . By the remarkablystrong negative polarization produced by these threesubstances. 3 . By the destruction of its smell and of

its polarity by all bodies which take up or combinechemically with chlorine ; for example , easily oxidizedmetals

,stannous c hloride , ferrous chloride, ferrous

sulphate,alkaline solutions

,etc. 4. By its power O f

destroying vegetable colours with great energy. 5 .

By its power of instantly decomposing po tassiumiodide and setting iodine free ; of turning potassiumferrocyanide into ferricyanide ; of breaking uphydrogen sulphide

,hydrogen selenide, etc. of con

verting sulphurous into sulphuric acid in the presenceO f water, thus decomposing water under exactly thesame conditions as chlorine ; and of being destroyedby ammonia. I might mention yet more chemical

AND SOHONREIN 47

facts which all go to establish , in the most satisfactorymanner

,the analogy between chlorine and my

ozone.

I have no doubt that you will be astonished whenI tell you how ozone can be produced chemically , forthe conditions of its formation are such as would notlead one to expect in the remotest degree the resultswhich are actually obtained. The method is thisCommercial phosphorus is allowed to stand in a flaskfilled with atmospheric air. If the temperature O f theexperiment is only a few degrees above zero

,the air

above the phosphorus somewhat rapidly assumes apositive potential , that is , it has the power of polarizing positively a strip of gold-leaf held in it . If thetemperature is not raised in any way the air remainsin this vo ltaic condition and smells of phosphorus

,

i.e.,like garlic . But if the air is warmed to 8- 12°

its positive potential changes rapidly to the Opposite ;that is

,it assumes the power of polarizing a gold-leaf

negatively. This change O f the electrical condition isaccompanied by an alteration of smell . The air nowsmells just like electricity discharging itself from apoint , or like the oxygen which is set free

,for

example,on the positive pole in the electrolysis O f

acidified water. The higher the temperature the

more rapid is the change which I have described ;and if the phosphorus is heated almost to its meltingpoint

,the alteration of smell and O f voltaic condition

occurs in the course O f a few minutes,or even in a

much shorter time ; while at the ordinary temperature several hours are required . When once the


negative polari z ation or the electrical smell hasbecome perceptibly strong

,a moist or air-dried strip

of litmus paper plunged in the air is fairly rapidlybleached and tincture of litmus or indigo solution isdecolorized , exactly as it is by chlorine . If such airis shaken with potassium ferrocyanide solution the

liquid becomes intensely yellow,and when treated

with pure ferrous sulphate gives a blue precipitate .

Potassium iodide solution shaken with it is turnedyellow

,and moist starch paste mixed with this salt

instantly becomes blue.

I may mention here that strips of paper soaked instarch solution containing potassium iodide form the

most convenient and the most delicate test for ozone ;they indicate its presence even when a very sensitivegalvanometer fails to do so

,or when the smell cannot

be perceived .

Just one example to prove the truth of this statement. A small piece of phosphorus still coveredwith moisture will not turn blue a piece O f testpaper held above it

,b ut if the phosphorus is rubbed

with blotting paper,with gentle friction

,the paper

becomes decidedly blue in the course of a few seconds .It is a remarkable fact that very small quantities O fe ther or alcohol vapour

,O lefiant gas, as well as some

o ther vapours and gases,such as sulphurous acid ,

hydrogen sulphide , etc .

,entirely prevent the forma

tion of ozone in atmospheric air ; and this is theaction generally Of all substances which arrest theluminescence or slow combustion of phosphorus inthe air. I must here mention that in pure oxygen


bleached by electricity in the following manner.The strip

,in a moist condition

,was placed on a

platinum plate which was in metallic contact withthe earth . A brass wire was fixed to the conductorof the electrical machine so that its free end reachedto within a third of an inch O f the strip . When theelectrical machine was set in motion,

part of the stripwas thus in the electrical brush

,that is

,in the place

where the electric smell was most distinctlyperceptible.

A fter the machine had been worked continuously forfour hours the strip appeared bleached as you see it.

("ou will perhaps be interested to learn that thestrip which I am sending you is the very one withwhich I for the first time proved the bleaching powerof the electrical odour , and that this first experimentwas performed on the 7th of April 2 . The

power possessed by the odoriferous electrical materialO f converting potassium ferrocyanide into ferricyanide.

A drop of ferrocyanide solution brought under theabove conditions assumes even after a few minutesa deep yellow colour , and then on treatment withpure ferrous chloride or sulphate gives a decidedblue precipitate . A fter a thousand turns of mymachine

,a drop of such a solution gives a dark

blue precipitate . 3 . The power possessed by the

electrical O dour of almost instantly turning starchpaste containing potassium iodide blue. This powerhas indeed long been known

,but it has been errOne

onely interpreted ; for the separation of iodine doesnot depend on the electrical decomposition of the

haloid salt,nor essentially on the formation O f nitric

AND SOHONREIN 5 1

acid,as Faraday supposes . It is to the production

O f ozone by the e lectricity that this action must beascribed . 4. The property O f the electrical odour ofbeing destroyed by sulphurous acid, hydrogen sulphideand hydrogen selenide . I f in the neighbourhood of apoint from which electricity is being discharged themerest trace of sulphurous acid is developed

,as for

example by burning the sulphur of an ordinary match,

the peculiar smell which accompanies the dischargeof electricity into the air is perceived no longer .Furthermore the electrical brush is no longer ableunder these conditions to communicate negativepolarity to a gold or platinum strip held in it

, or to

turn potassium iodide s tarch paste blue. Moreoverif such a strip is held only for a moment in a flaskcontaining some sulphurous acid

,it will not be turned

blue when exposed to the action of the electric brush .

The action of hydrogen sulphide and selenide is

similar to that of sulphurous acid ; the presence of

the smallest quantities of these substances in the

room containing the electrical machine is sum

cient

to prevent the production O f the electrical odour atthe point of the conductor and all the reactions depending upon it. Now these substances destroychemically or voltaically prepared ozone in exactlythe same manner as the electrical odour. Hardlyany doubt can remain as to the identity of the ozoneprepared in the three ways described , and it may betaken as incontestable that during the discharge of

e lectricity into the air a haloid substance Similar tochlorine is formed. Now since lightning is nothing


but the restoration of electrical equilibrium on alarge scale

,it seems to me to be certain that the

smell or pungent vapour observed after a flash of

lightning is nothing but my ozone. A t any rate itmust form an important constituent of the O doriferous body which is so produced. My investigationshave shown that ozone is not produced either in pureoxygen or carbonic acid under conditions of temperature in which it is produced quite easily in atmos

pheric air ; and I have also found that in air whichis completely dried with calcium chloride

,my test

paper is coloured perceptibly blue , after this eu

hydrous air has been allowed to stand for some timewith phosphorus . Now this experiment seems toShow that water also contributes nothing

'

to the

formation of ozone.

1 But if so,there is no known

constituent of the atmosphere left from which the

ozone could possibly originate,

except nitrogen.

Though it is a very remarkable fact that ozone

should be produced by the electrolysis of water,and

also by the discharge of electricity in the air, yet it

is still more extraordinary that so eminently electronegative a body as this can be formed in the presenceof phosphorus and even by its means. Indeed if asmall piece of phosphorus is placed in a flask containing ozonized oxygen collected at the positive pole O fa battery , the ozone smell , the bleaching power, the

1 This remark is particularly interesting, because it is diametrically opposed/

to his later view, which prevented him for

such a long time from accepting Marignac’s explanation of the

nature of ozone,and de la Rive’s proof that ozone can be

formed in the absence ofwater.

AND SCHONBEIN 53

negative polarity,and

,in fact

,all the properties of

ozone alr eady specified disappear. If you take apiece O f phosphorus which would not shine in the

dark or colour a piece of my test paper placed nearit

,and hold it near a point from which electricity is

be ing discharged, no ozone is developed at the point,starch paste containing potassium iodide is not turnedblue

,and generally none of the phenomena which I

have described as accompanying the electrical brushare O bserved Are we then to suppose that voltaicand electric ozone are different from that which isprepared from atmospheric air by means of phos

phorus, and that chemical ozone cannot combine with

As a fact there is no such difference , as the following experiment shows . If a few drops O f ether areallowed to fall into a flask filled with chemical ozone

,

and then a small piece of phosphorus added,the ozone

smel l rapidly disappears , and the test paper is no

longer turned blue by the air in the flask. The ozonealready present in a flask containing air and phos

phorus is always destroyed , if by any of the meanswhich I have described

,or in any other way

, the

luminescence of the phosphorus is checked,that is

,

its slow combustion prevented. To this,therefore ,

is attributable the fact that the voltaic condition of

the air above the phosphorus can be repeatedlyaltered, and depends essentially on the temperature ;so that this air is sometimes positive , sometimesnegative

,and sometimes neither . I may mention in

passing , that according to my experiments the

D


positive polarity of this air is chiefly due to phos

phorus vapour , and also partly to traces of hydrogenphosphide ; and it is easy to see from what I havesaid

,that these substances would exert a destructive

action on the ozone . This action of phosphorusvapour may easily be shown by putting a test paperfirst into it and then into an atmosphere of ozone .

As long as any traces of phosphorus vapour adhereto the paper it will not be turned blue . Conversely

,

if a test paper is turned blue by ozone and thenplunged into an atmosphere containing phosphorusvapour, the blue colour disappears.Finally I must mention , that if ozone is breathed

in small quantities it produces on the organism effectssimilar to those produced by chlorine : coughing,oppression of the chest

,in short

,all the symptoms of

a cold. A mouse placed in a flask filled with air con

taining only very smal l quantities of ozone died afterfive minutes in violent convulsions . From the resultsdescribed above , as we ll as from certain other factswhich I have discovered

,some of which still remain

to be mentioned,it seems to me that we may con

clude with a fair degree of certainty that nitrogen isthe source of ozone

,or, to be more explicit , that

nitrogen consists of ozone and hydrogen. Howeverdifferent the circumstances under which ozone is

formed may appear at first sight,there is yet one

condition which the electric,voltaic , and chemical

methods of production all fulfil alike,and that is

the presence of nitrogen. The formation of ozone byordinary electricity

,by the voltaic current, and by

AND SCHONBEIN 5 5

means of phosphorus may be explained as follows1. Electrical method of separation. Just as Ordinarye lectricity decomposes a series of gaseous hydrogencompounds , especially in the presence of oxygen,

so,

when it is discharged from a point into the air, it

determines the combination O f the oxygen with thehydrogen contained in the nitrogen and sets free theozone. If instead of ni trogen hydrogen ozonide)the atmosphere contained hydrogen chloride

,the dis

charge O f electricity into the air would also produce asmell

,the feebler smell of chlorine ; and, moreover ,

the chemical actions which under these circumstancesthe electrical brush would produce, would be quiteanalogous to those which are actually O bserved .

2 . Vo ltaic mode of production. The nitrogen,that is

the hydrogen ozonide,dissolved in water is

,like

hydrogen chloride,an e lectrolyte . It is decomposed

by the current,its hydrogen being set free at the

negative pole,and its ozone at the positive . Boiled

out water,i.e.

,water free from nitrogen , does not give

the smallest trace of ozone on e lectrolysis,but if

shaken with air or nitrogen,then on passing the

current, ozone is again set free at the positive pole .

Hitherto I have not been able to find anything atthe negative pole but hydrogen. I may mentionhere that the presence in the water of the smallestquantities of sulphurous acid , hydrogen sulphide , andother substances

,which for example would prevent

the e lectrolytic liberation of chlorine , also stop theformation of ozone . Sometimes even distilled watercontains substances which prevent its formation, even


when our reagents are unable to detect the presenceof any foreign body in it. 3 . Chemical method of

formation. Phosphorus in a state of Slow combustionexerts a catalytic action on the oxygen and nitrogenin contact with it

,causing the former to combine

with the hydrogen of the latter and set the ozone

free . Part of this ozone appears as a gas and mixeswith the air

,while another part combines with the

phosphorus to form phosphorus ozonide,which is de

composed by the water present into phosphoric acidand hydrogen ozonide

,i.e.

,nitrogen. This is the

reason why in moist atmospheric air the oxidationof phosphorus proceeds so comparatively fast

,and it

also explains the fact,that in the slow combustion of

phosphorus in air,not only phO Sphorous acid is pro

duced, but also phosphoric ; the latter is undoubtedlyformed by means of ozone

,while the immediate

resul t of the slow oxidation of the phosphorus is theproduction of the former.Similarly in the light of the facts which I have

discovered we can understand the long known and

remarkable property of nitrogen,of supporting the

luminescence of phosphorus . A ccording to my ex

periments, air standing over phosphorus and calciumchloride does acquire a power of turning my tes tpaper blue , but very little ozone is formed under theseconditions , and hence very little phosphoric acid ,because the air cannot at first contain any watervapour, and the water produced by the action of theoxygen on the hydrogen ozonide is mostly absorbedby the calcium chloride . Probablythe formation Of


P S . 1.— O f the enclosed strips of litmus paper

NO . 1 is bleached by electrical ozone.

NO . 2 by voltaic ozone .

NO . 3 by chemical ozone .

P S . 2 .

— I must add that I have O btained potassiumnitrate by treating chem ically-prepared ozone withpotash solution. I am hoping to discover , as well aspotassium ozonate

,i. e. ,

nitrate , potassium ozonide. Itis

,no doubt

,chemically possible that ozone

,air

,and

potash may give potassium nitrate . But at any ratethe fact that potassium nitrate is found under theseconditions is a very remarkable phenomenon,

and

seems to go far to confirm the view expressed in myletter that nitrogen is hydrogen ozonide.

An extensive extract from this detailed letter wasprin ted in the fifth number of the first year’s publi cation of

the Ofversigt af Kongl. Vetenskaps Ahademiens forhand

lingar of 15 th May 1844 [vol i.,p . 71—7 and

next day Berzelius wrote personally to S chOnbein. He

thought that the whole ozone question was still waitingfor a satisfactory solution,

as is shown by the remarkswhich he appended to Scho’nbein’s letter

,by his own

letter,and still more clearly from the Jahresbericht.

He considered ozone,as he says there

,to be a

“

prohle

matic body.

”

We need not be surprised at Scho’nbein’s bold assump

tion of the decomposition of nitrogen . Berzelius wasjust the man whom he might expect to encourage himin this view

, for in his inmost heart he had alwaysbelieved 1 in the compound nature of nitrogen, although

1 Cf. Rose , Geda'

chtnisrede auf Berzelius, Berlin p. 27.

AND SCHONBEIN 5 9

he was no longer prepared to stand by the assertion hemade in 1818 “ that the compound nature of nitrogen isnot to be regarded merely as a hypothesis, but, if we grantthe law of constant proportions, as an almost establishedfact3’ 1

Berze lius to S chonbe in

STO OKHO LM,l 6th May 1844.

M" DEAR SIR,I thank you sincerely for your extremely

interesting letter of 14th April,and for the scientific

novelties which it contains . In accordance withyour wish I laid it before the Royal Academyat their last meeting , and they ordered that an

extract from it be pr inted among their Transactions ofthat mee ting.

Now that you are able to produce ozone chemical ly

you could surely saturate a sufficient amount of air

with it to enable you to O btain its compounds inweighable quantities . If

,for example

, you were to

1 Unersb‘

kning of Quafcets, V a tets och Ammoniakens natur .

E isinger Ajhandl. i Fysih, vol. v. (1818) p . 198 ; G ilbert,A nnal. , vol. xlvi . (1814) p . 148 . Previously, p . 133 , he says“ But my Object is to prove that neither G ay-Lussac

’s analysis

of nitric acid,nor my own statements about the hyperbasic

salts considered above (the reference is to basic lead nitrate) areright, and to Show how by correcting these two analyses we canremove satisfactorily all the objections which have hithertoappeared to render the theory of the compound nature of

nitrogen untenable.

”


put into your large glass flask,as well as phosphorus ,

a flat vessel containing an amalgam of silver,lead ,

z inc or tin ,it seems to me that the metal dissolved in

the mercury would necessarily combine with ozone

to form a metallic ozonide,and the compound could

thus be prepared without the disturbing influence ofwater

,particularly if the metal chosen were one

which was not attacked by the vapours of phos

phorous acid . A fter several weeks or a few monthsan arrangement of this kind might give a sufficientquantity of the substance for investigation .

Your theoretical ideas are extremely simple andfor that reason one would be glad to believe in them .

O n the other hand they offer great difficulties . Whatare the oxidation products of nitrogen if N = O zH ?A re they O zH 1 , 2 , 3 and 5 atoms of oxygen ? Inthat case O zH shows an inexplicable difference incharacter from the ordinary substances which formsalts

, for it ought to be a strong hydracid. Againphosphorus

,arsenic

,and antimony form compounds

analogous in some degree to ammonia ; but all of

them contain three equivalents of hydrogen,while

ammonia would have to be written O zH4.

O n the other hand if nitric O xide , nitric acid, etc. ,

are to be O z , O z the theory does not accord with thecomposition O f these bodies, and particularly not withtheir densities

,the experimental values of which

agree so exactly with those calculated from theircomposition. If , a certain quantity of hydrogen gaswere driven out of the compound, in the combinationof nitrogen with oxygen ,

the gaseous product so formed

AND SCHO NBEIN 61

should have a decidedly higher density. Indeed I do

not think the problem is yet in a position to be

solved . "ou must submit the older experiments of

G Ottling1and B

'

ockmann 2 to revision ; it is possiblethat in their papers on the luminescence of phos

phorus in nitrogen (particularly in that of the latter ,who declares that nitrogen disappears) you may findfacts which will suggest to you new methods ofresearch . The investigation is so important that youmust follow it up with the true Bunsen perseverance ,3

and not abandon it until,if

,possible , we are perfectlyclear about it.I wish you patience and good luck in your research

and with assurances of the greatest respect ,I remain

,

Yours most sincerely ,JAc. BERZELIUS .

1Johann Friedrich August G Ottling, born at Derenburg nearHalberstadt in 175 5 , died at Jena 1809 . He was first an

apothecary,and then professor of chemistry, pharmacy, and

technology at Jena Etwas uber den Stickstoff und das

Leuchten das Phosphors in Stickluft,” Gren. Neues Journ. , vol.

i . (179 5 ) p . 1 .

2 CarlWilhelm Bockmann,born at Karlsruhe in 1773, died

in 1821, teacher O f physics at the gymnasium there “ V er

suche uber das Verhalten des Phosphors in verschiedenenG asen,

”Erlangen, 1800 .

3 He no doubt alludes in particular to Bunsen’s investigationson cacodyl which were begun in 1837, and whose conclusionBerzelius had announced in the volume of the Jahresbericht

which was laid before the A cademy on 3 lst March.


S chonbein to B e rzelius

M" DEAR BARON,

Since you considered my papers on ozone

worthy of your attention,I flatter myself that you

will be interested to hear of the results of my investi

gations on a kindred subject. O wing to want of

space I will confine myself to general outlines ,especially as a detailed account of the substance inquestion will shortly be published.

1 The combustionof phosphorus in atmospheric air and the formationof a highly electro-negative body possessed of markedoxidizing properties, my ozone , directed my attentionto the combustion in air of bodies generally

,especially

to cases analogous to the gradual oxidation of phos

phorus, such as the partial combustion of ethervapour at comparatively low temperatures. Byanalogy

,and in accordance with my theoretical

views as to the nature of nitrogen,I anticipated the

formation of a body with electro-negative and oxidiz

ing properties . "ou will see that my results showthat the gradual oxidation of ether vapour (as well asthe rapid burning of bodies in general) is accompaniedby phenomena which so far have escaped the noticeof chemists , but which certainly appear to me to be

1 “ Uber die langsame und rasche Verbrennung der Korperin atmosph

‘

arischer Luft.” Bails, 1845 . Dated 5th June 1845 .

AND SCHONBEIN 53

we ll worth careful attention. When a mixture of

e ther vapour with atmospheric air is partially burntby

'

means of a moderately heated platinum wire ,a substance is formed which has the followingproperties

1. It decolorizes indigo solution.

10 .

11

It decomposesu potassium iodide and hydrogeniodide , setting Iodine free , thus turning papermoistened with starch and potassium iodideblue .

I t decomposes potassium bromide , though not

very readily .

It converts potassium ferrocyanide into the red

prussiate of potash .

It immediate ly imparts a deep colour to whiteferrous cyanide .

It changes ferrous into ferric salts.

In the presence of water it oxidizes iodine toiodic acid.

In presence of water it changes sulphurous intosulphuric acid .

It readily decolorizes sulphide O f lead and othermetallic sulphides , apparently convertingthem into sulphates .

It renders an aqueous solution of sulphurettedhydrogen unable to precipitate lead salts .

A concentrated solution of the substance,

possessing all the aforementioned proper ties ,


loses them SO soon as it is brought in contactwith oxidizable substances , e.g .

,sulphurous

acid or metals.

Even mercury reacts in this way , with the

formation O f a mercury salt soluble in water.

I f hydrogen is burned in atmospheric air and thefollowing liquids are held over the point of the flamein narrow tubes

,the following reactions take place

1 . Indigo solution becomes decolorized .

2 . Iodine is liberated from potassium iodide andhydrogen iodide solutions or paper moistenedwith starch paste and potassium iodide becomes blue.

3 . A potassium ferrocyanide solution assumes anintense yellow coloration

,is

,in fact

,converted

into potassium ferricyanide .

4. White ferrous cyanide suspended in water turnsdark blue .

5 . A ferrous salt in solution is converted into aferric salt .

6 . Aqueous sulphurous acid is transformed intosulphuric acid .

7. Lead sulphide suspended in water is bleached.

A slip of paper saturated with water andcoloured " brown with lead sulphide turnswhite on being held over the point of the

flame.


substances,that is to say, whether the substances

formed by the gradual oxidation O f phosphorusand of ether vapour are identical with thoseproduced by the rapid combustion pf the otherbodies

,must be decided by further investigations.

At any rate this important fact remains , that thesubstances in question Show a remarkable resemblanceto one another in their properties . That they havenothing in common with nitric or nitrous acid

,is

obvious from the way in which they are produced ;but there are also other reasons which go against thisassumption. The facts I have mentioned hardly overthr ow my hypothesis as to the nature of nitrogen ;they go to show that high temperatures would causethe oxygen of the air to combine with the hydrogenof the nitrogen and set ozone free ; this may be compared to the way in which I imagine the catalyticinfluence O f phosphorus or ordinary electricity wouldact on a mixture of oxygen and nitrogen. However

,

I do not wish to attach any great importance to thisview ,

but only add that such results possess a peculiarinterest in regard to the opposite chemical effectcaused by the two parts O f the blow-pipe flame. Ihave no doubt that the oxidizing power of the outerflame is due to some peculiar substance and not

directly to ordinary heated oxygen.

I should O f course be glad if you would communicate the contents of this letter to your A cademy

,if

you think it of sum

cient importance.

I hope that this note will find you in good health ,

AND SCHONBEIN 67

and I trust that you will honour me soon with a fewlines in reply .

With the profoundest respect , I have the honour toremain,

Yours most O bediently,

C . F. SCHO NBEIN.

P .S .— I trust you have received my paper on ozone.

BALE,15 th January 1845 .

This letter also was read at the Academy in Stockholm,

and a summary of it appeared in the Ofcersigt of Konyl.

V etenshaps Akadamiens forhandlingar [vol. 2 . (1845 )p . Two days after this meeting

,which took place

on 12th February,Berzelius sent the following reply

to Sch '

o’

nbein

Berzelius to S chonbe in

STO CKHO LM,14th February 1845 .

DEAR S IR,

I thank you very much for your interestingcommunication in your las t letter O f 15th January

,

which I read before the A cademy and which theyare publishing in their Transactions. I think youhave proved that ozone is always formed duringcombustions in atmospheric air ; hence there only


remains the further step of producing an unmistakable compound oi this body with some other in suchquantity as to make it possible to study its propertiesaccurately. If you lead a current of air first throughether and then through platinum sponge— this can

readily be effected by means of an aspirator,and

continued for weeks together —you might collect aconsiderable quantity of the products of combustion ;they would be little else than water , carbonic acidand ozone. If , as you state , the liquid dissolvesmercury

,forming a soluble salt

, you might condenseit over mercury and thus O btain a quantity of the

mercury salt,whose properties could then be

investigated .

I did not get your detailed paper , but I amacquainted with it from the French translation inde la Rive’s A rchive de Z

’Electricite.

1 I candidlyconfess that I amnot quite satisfied with the experi

mental part of it ; in the first place the preparationO f the potassium salt is tremendously laborious , andin the next place the reactions which you haveperformed with the new salt are not carried out

on correct principles. For you assert that allacids evolve from it an odour of ozone, the aciduniting with the potassium. This is much asthough sulphuric acid were to produce a smell ofchlorine with common salt. "ou should have triedit with chlorine or bromine water in order

,to set

ozone free . If,however

,which I do not doubt, your

assertion be correct, the O dour must be due to hydro1 A rchives de l

’Electricite’

, vol. iv. (1844) p . 333 .

AND SCHONBEIN 69

ozonic acid ; now if such an acid does exist and canbe prepared , it seems fairly evident that nitrogencannot be hydrogen ozonide. It would therefore bebe tter to put on one side all theoretical conjecturesas to the constitution of ozone and nitrogen and tostudy the properties of ozone itself. When once youhave caught it

,it will be easier to theorize about it .

I hope you will excuse my candid remarks.

With the kindest regards,I have the honour to remain,

Yours O bediently,JAC. BERZELIUS.

From the postmark this letter reached Bdle on the 26thO f February ; Sch

'

o’

nbein therefore answered it by returnof post.

S chOnbein to Berzelius

M" DEAR BARON ,

I must ask you to forgive me for troubling you'

so soon with another letter but some remarks which

you were so good to make on my Iarger research concerning '

ozone , in your honoured letter of the 14th oflast month , have induced me to send you a few wordsin reply. In the first place I take the liberty of remarking that the paper in question

,in the last

numbe r O f de la Rive’s A rchives, absolutely teems


with errors of translation ,so that in some cases its

meaning is the exact opposite of that of the Germanoriginal.In my paper the salt obtained by the complete

decomposition of potassium iodide by means of ozonewas not said to be pure potassium ozonide (althoughI was certainly inclined at first to think it was that) ;on the contrary it was expressly stated that it contained potassium iodate.

1 A lso I have nowhere said,as far as I know

,that all acids gave with this salt

a smel l of ozone. I did indeed remark that sulphuricacid set free from it a constituent which had a smellapparently intermediate between that of bromine and

that of iodine, and which turns potassium iodidestarch paste blue , etc. , but I did not venture definitely to ascribe this smell to ozone

,though I

expressed an inclination to believe that it was due toit . A ssuming that the salt in question containssome potassium iodate as wel l as potassium ozonide

,

I expressed myself to the following effect as to thesupposed development of ozone, on pages 116 and 117of the German paper z z

“ The production of ozonefrom this mixture of salts by means of sulphuric acid

,

the brown colour which the acid causes,and the

evolution of iodine vapours on warming,are satis

factorily explained if we suppose that the salt inquestion is a mixture of potassium iodate and

1 Cf. also Berzelius’ remarks in the Jahresbm'

cht,vol. xxv.

(1846) p . 132 .

2 Schijnbein is here referring to the earlier paper : Uber dieErzeugung des Ozons.

AND SCHGNBEIN 71

potassium ozonide. The sulphuric acid separates theiodic acid from the potash , and part of the oxygen ofthe latter acid combines with the potassium of the

ozonide,setting free iodine and ozone.

” This singlepassage is

,I think

,su

m

cient to place the point inquestion in the right light. It was not because Ihad not thought of the method that I did not treatmy salt with chlorine . But I only had

, so to Speak,homoeopathic quantities of the salt , and so I couldonly perform a few incomplete experiments with it ;and as I wished to see whether I could obtain fromit a body similar in its reactions to chlorine or ozone

,

I intentionally abstained from employing the former.O riginally I mixed my salt with pure manganesedioxide

,and then on treating it with sulphuric acid

I obtained the reactions I have described ; but Ifound out later that the manganese dioxide wasquite unnecessary , and that the reaction was due tothe presence of potassium iodate . The fact that asolution of the salt , when treated with any acidcolours starch paste containing potassium iodide blue ,likewise makes the presence of potassium iodate conceivable . However

,I do not attach any importance

to these preliminary experiments,

' since they wereperformed

,as I have said

,with such small

quantities ."ou are quite right in saying that the plan which

I have adOpted of using potassium iodide to absorbthe ozone

, liberated by means of phosphorus , is verylaborious, but I am bound to say that up to thepresent moment I know of no better. Mercury

, for


instance,takes such an endless time to absorb ozone ,

set free by phO Sphorus, that I can hardly believe itwill ever be employed as a means of separating it .A t all events the fact is, that there is no materialwhich is able to take up ozone more rapidly thanpotassium iodide. I willingly admit that youare quiteright in blaming me for indulging in my paper in toomuch speculation about ozone ; I will not attempt tojustify this offence even by saying that it is never sooften committed as in chemistry , as has been amplyshown in recent times. I am sure that you willreadily grant that the circumstances under whichozone is produced inevitably lead one to think of the

possibility of nitrogen being a compound. Howeverbaseless my hypothesis as to the nature of this bodymay be

,it has guided me in all the experM ents I

have hitherto made , and has led me to a series ofdiscoveries . Whatever ozone may prove to be , thismuch seems to me to be certain ,

from its voltaic andchemical properties , that it is not a hydrogen com

pound or at least not a hydracid.

As soon as I am quite wel l again I shall continuemy experiments on ozone with renewed zeal ; but Ihave for some time been condemned to inaction in

consequence of a cold which I have no doubt that Icaught through breathing too much of the gasesproduced by the slow combustion of ethervapour.I have for a long time been very anxious to visit

your beautiful country,and as soon as I am able to

carry out my project I shall lose no time in doing so


A fter all my attempts to isolate ozone had failed,and I had never got any resul ts save oxidations , Iwas induced to reconsider the conditions under whichozone is produced. Five years ago, when I preparedozone voltaically, my first idea was that it was a bodyin a higher state of oxidation ; and so starting againfrom this view I investigated the part which waterplays in the production of the substance. I foundthat by the action of atmospheric air on phosphorusin contact with water at ozone is produced inlarger quantities than in any other case

,andmoreover

that its production is continually diminished as theair approaches nearer to dryness . Just the sameresults were obtained if I performed the experimentwith a mixture of ozone and carbonic acid

,but no

ozone was produced if oxygen alone,or nitrogen , or

carbon dioxide was allowed to act on the phosphorus.It seemed therefore as if ozone was produced fromoxygen and water, and as if nitrogen played no

essential part in its formation.

As much as five years ago I published my observations that the discharge of electricity from a heatedpoint did not produce the so-called electrical smell

,

and that the voltaic current was not able to set freeany ozone from heated water .1 Similarly I foundthat a heated platinum strip held in the dischargefrom a cold point receives no negative charge

,just as

happens when the point is hot and the strip cold.

Therefore , proceeding on the hypothesis that ozonemay be a higher oxidation product of hydrogen which

1 Poggend. Annal., vol. 1. (1840) p . 618 .

AND SCHONBEIN 75

is decomposed by heat, I made the fol lowing experi~

ments. O zone was produced in a large flask by theusual chemical method in as large quantities as

possible , and a suitable arrangement was madewhereby the atmosphere charged with ozone wascaused to pass through a narrow glass tube into theair. As long as the tube was not heated , the issuingair had a smel l quite indistinguishable from thatnoticed in the neighbourhood of a point from whiche lectricity is being discharged, and it also producedall the chemical and voltaic reactions which are

charac teristic of chemical , voltaic and electrical ozone .

Thus it gave a negative charge to platinum , it turnedstarch paste containing potassium iodide blue, itdestroyed vegetable colours , etc. But if about an

inch of the tube is heated by means of a spirit lampthe peculiar smell disappears, and at the same timethe air loses all its peculiar properties . If the tubeis allowed to coo l again,

all these properties reappear .Voltaic ozone of course behaves in exactly the sameway under the same conditions. The completesimilarity of the action of heat on chemical , voltaicand electrical ozone may serve as a further proof ofthe identity of these substances .A few days ago my friend Marignac 1 of Genevainformed me of the results of the experiments whichhe has carried out with a view to the isolation of

ozone and the determination of its properties . They

1 Jean Charles G alisard de Marignac, born at G eneva in1817, died in 1894. Professor of chemistry at the Universityof G eneva from 1842 to 1878 .

76 LETTERS or BERZELIUS

are so interesting that I venture to communicatethem to you. This distinguished chemist obtainsfrom water complete ly freed from air and acidifiedwith pure sulphuric acid, large quantities of ozone ifthe liquid is kept cool. Finely divided silver , whichrapidly absorbs ozone , forms with it nothing butsilver oxide ; potassium iodide gives only potassiumiodate and some carbonate . He fails

,as I did, to get

any ozone with pure oxygen or with carbonic acidor nitrogen , but he obtains it from both the twolast-named gases as well as from hydrogen

,if they

contain free oxygen. It is easy to see by comparingMarignac

’

s results with mine , that the two seriessupplement and confirm one another

,and I think we

may fairly conclude from them ,that oxygen and

hydrogen are the constituents of ozone , and that thelatter is formed whenever oxygen comes in contactwith water under the requisite conditions . The pro

duction of ozone in the electrolysis ofwater can easilybe understood ; to explain the action of phosphorusand electricity, we must suppose that they exert acatalytic influence on the oxygen and the water. The

following facts seem to make it certain that ozone isnot identical with Thénard

’

s hydrogen peroxide.

1

The latter has no sme ll, disso lves in water in all proportions , communicates to platinum , according to

Becquerel’s and my own observations,a positive

charge , and is converted by the catalytic action of

1 Thenard, Mémoire sur la combinaison de l’oxigene, et surles propriétés extraordinaires que possede l

’eau oxigénée,

”

Ma’moires dc Paris

, vol. iii. (1820) p . 385 .

AND SCHONBEIN 77

silver into water and oxygen : whereas ozone is dis

tinguished by a highly characteristic smell , scarcelydissolves in water even in traces , charges platinumnegatively

,and oxidizes silver. Since ozone is pro

duced by the influence of e lectricity in atmosphericair and since restorations of electrical equilibriumare

,continually occurring, it follows that the air must

contain ozone. Now in the open air starch paste

containing potassium iod ide turns blue, and po tassiumiodide forms the iodate with the liberation of iodine

(though only to a small extent) ; and since in a closedvessel none of these phenomena occur , and since theyare produced by the action of ozone on potassiumiodide , it would seem that we ought to ascribe themto the atmospheric ozone . But if so , many slow cxi

dations which take place in the air, such as bleachingand various other similar phenomena

,must also be due

to the atmospheric ozone,and not to the free oxygen

of the air. From the powerful physiological effectsof ozone

,its presence in the air may have a medical

interest. The luminescence of phosphorus in atmos

pheric air , which has so long been known and is soli ttle understood , can now be explained fairly satisfactorily. The catalytic influence of the phO SphO I

‘

llS

determines the combination of the oxygen and the

water to form ozone,which in its turn oxidizes the

phosphorus to phosphoric acid. The simultaneousproduction of phosphorous acid is no doubt due to

the direct combination of the atmospheric oxygenwith the phosphorus. In absolute ly dry air theluminescence of phosphorus is excessively feeble, and


no ozone is formed,from which it would seem to

follow that the production of light depends chieflyon the oxidation caused by the ozone. A t least it isa fact that the amount of ozone formed is exactlyproportional to the intensity of the luminescence 1

of the phosphorus . The great similarity betweenozone and chlorine leads one to think of the old viewsabout the latter

,and it is possible that sooner or later

this hypothesis , which you supported for so long, mayagain become the subject of discussion.

Pray communicate the contents of this letter tothe Royal A cademy if you find it su

” ’

iciently interesting.

With the greatest respect,I have the honour to remain , my dear Baron ,

Yours very sincerely,C . F . SCHONBEIN.

BALE,22nd March 1845 .

It seems from this letter, from the paper “ Uber dieNatur des O zons LPoggend . Annal. , vol. lxv. (1845 )p . which is dated Holy-Thursday, 1845 , t.e. ,

2otb

March,and from/the simultaneous publication of the two

works in the Archives de vol. v . ,Marignac,

pp . 5—11 Schonbein,pp. 11—23

,that Sch '

o’

nbein was not

1 We do not yet know why the catalytic influence of phos

phorus is not exerted in oxygen of the ordinary density, butonly when the gas is rarefied to a certain extent either by itselfor by dilution with certain other gases . [This note is byS chbnbein.]

AND SCHONBEIN 79

led to his new view as to the nature of ozone byMarignac,but only confirmed in it by the simultaneous work of thelatter .

1


M" DEAR BARON,

I take the liberty of sending you, by favourO f Herr von Mitscherlich

,two papers which I have

just published on ozone and kindred subjects . Ihope you will receive them with indulgence, as aslight mark of my unbounded esteem .

I have for some time been busy with experimentson the formation of nitric acid, and I have beensuccessful in discovering some facts which appearto me to throw a certain amount of light on thissubject

,which has hitherto been very imperfectly

understood. I have come to the conclusion that theproduction of nitric acid is closely connected withthe action of ozone ; it seems that the latter, undersome conditions, can oxidize nitrogen to nitric acid .

This much is certain,that nitric acid is formed in

the production of ozone in atmospheric air by thechemical method (by the means of phosphorus) , justas it is by passing electric sparks thr ough a moistmixture of oxygen and nitrogen . This is evident

1 Of. Engler, Historisch-Kritische Studie uber das O zon(reprint from the Leopoldina), alle p . 8 .


from . the fact that the so-called phosphoric acid,produced by the phosphorus in moist air , alwayscontains nitric acid. I shall soon publish inPoggendorfi

’

s A nnalen some more details on thisnot uninteresting subject . "ou may possibly beinterested to have a little sample of the bleachingaction of ozone, and so I have taken the libertyofenclosing two strips 1 of linen , one of which has beenhung for about a fortnight in air which has beenozonized by means of phosphorus. The second isa sample of the unbleached stuff. I must add thatthe bleaching of the white strip was accomplishedsolely by means of ozonized air .I am still wholly unable to understand how they

can have found in the Giessen laboratory that bythe action O f phosphorus on mois t air no substanceis produced which bleaches , decomposes potassiumiodide

,and in other ways shows itself a strong

oxidizing agent . I confess that the experimentshave been performed there in a way which could notlead to any but negative results .We had almost persuaded ourselves here that on

the occasion of your recent visit to Germany weshould have the pleasure of seeing you in our house

,

and we had made preliminary arrangements to do

you honour ; but unfortunately these hopes, whichwere based on the statement of a man from Berlin ,have not been realized.

Indulging in the pleasant expectation of soon

1 Both strips are still enclosed in the letter.


1. However long it is exposed to the action of

water it retains its coherence,which

,moreover

,is

so much increased by my process that the paper hasa texture like that of parchment.

2 . A lso, acid and alkaline solutions, as, for example,water containing hydrochloric acid or potash , haveno destructive action on the prepared paper ; and soordinary and printing ink can be removed from itwithout injury to its durability.

3 . Thin and extremely brittle paper acquires,by

my process, a firmness and toughness equal to thatof much thicker ordinary paper of the toughesttexture.

4. N0 size or starch is required to make it available for printing and writing. It takes ordinary andalso lithographic printing with great ease.

5 . The detrimental action of bleaching powder isdone away with by my process.

These properties are of such a kind , I think , as toensure that my paper will be very much used ; and,moreover , my process has the advantage that itallows of a much larger number O f sheets beingmade from the same quantity of rags than in theordinary method of paper-making ; for, as I havealready said , my paper is decidedly stronger and

tougher than much thicker paper of the usual kind .

I have not yet ascertained how much thinner thewaterproof paper may be than ordinary unprepared

AND SCHONBEIN 83

paper of the same size so as to be equally tough ; butit is certain that a single thickness of the preparedpaper is at least as strong as a double thickness ofordinary paper.In order that you may be in a position to convince

yourself by actual observation that my paper doe spossess these properties

,I have taken the liberty of

enclosing some paper strips . Those which bear thesame numbers are taken from the same sheet

,one

being prepared and the other in its naturalcondition. If you put the strips into water , youwill easily be able to distinguish the preparedpaper from the normal paper by the diflerence intheir behaviour .It seems to me that my process

,which

,by the

way,is as cheap as it is simple , is particularly

adapted for preparing printing,packing

,and wall

paper. As enormous quantities of paper are usedfor these purposes , I should imagine that a knowledgeof my process would be we lcomed by paper-makers.I therefore venture to ask youwhether any influentialSwedish paper-makers would be inclined to putthemselves into communication with me with a viewto making use of my method

,or whether your

Government would receive instructions concerningthe details of it

,in the interest of the paper industry

of the country. "ou would oblige me exceedinglyif you would kindly give an answer to thesequestions.I shal l shortly send you a full account of the

means by which I have obtained these results , and of


the conclusions of my recent work in general whichmay perhaps serve as a communication to yourA cademy.

The transparent parchment-like leaf is modifiedvegetable fibre

,which I can prepare in any required

quantity.

In the pleasant anticipation of soon receiving ananswer,

I have the honour to remain ,With the utmost respect , my dear Baron,

Yours most sincerely ,O . F. SCHONBEIN.

P .S .-The unmarked bit O f paper had been printed

on,and the printer’s ink was removed by potash .

1

BALE , 5th March 1846.

These two letters of Schonbein’s of the 2oth of Sep

tember 1845 and the 5th of March 1846 also remainedunanswered, at least there is no reply among the paperswhich have come into my hands. But on the 8th of

April following Berzelius gave the A cademy an exhaustiveaccount (if the letter of March the 5 th, in which he alsoalludes to the earlier communication . O n this occasionhe once more referred expressly to Marignac

’s views as to

the nature of ozone .

I do not feel quite sure whether there was not anotherletter of Scho'nbein’s which is now lost, coming betweenthose of March 5 th and June 20th. His express1on 111

1 Seven different samples of paper are attached to this letter.

AND SCHONBEIN 85

the letter of June 20th seems to me to indicate thi s“ It will perhaps interest you to know that I have mademany experiments with my guncotton.

” This alone isenough to show that the writer assumes on the part ofBerzelius an accurate acquaintance with the than state O f

affairs ; and this would be simply and easily explainedfrom the correspondence which they were usually so fondof keeping up . Though according to Sch ’

onbein’s ownaccount in the Allgemez

'

ne Z eitung of 25 th O ctober 1846,the first experiments with guns on a large scale had beenperformed in the week April 6—12, and the discoveryhad attracted the attention of the general public to a

very unusual degree, Sch’

onbein had given a public lectureon his first invention for the first time as late as May

27th, before the Scientific Club of Bale . In this lecturehe referred directly to the experiments described in the

letter of March 5 th,on which moreover he had not

lectured to the Club till March 11th,after he had com

municated them to Berzelius . S O if B erzelius knew aboutthe experiments with guncotton he must have derived theimformation either from Schonbein directly or from noticesin the papers

,for the scientific journals had not yet

received accounts of them ; and this last assumptionseems to me

,as I have said, to be rendered untenable by

the expressions which Sch'

o'

nbein employs.


XVIII


DEAR S1R,

I hope you will forgive me for taking theliberty of introducing to you with these lines twoyoung men from Bale , Herr Merian 1 and HerrLanderer

,

2 and of commending them to your favourable no tice. They are going to travel in yourbeautiful country chiefly for artistic purposes."ou will perhaps be interested if I take this

occasion of informing you that I have just recentlyperformed numerous experiments with my guncottonboth with small firearms and with large guns

,and

I have O btained the most satisfactory results. For

instance I sent a shell weighing 15 lbs. (75 kgs.)1670 French feet from a mortar with one ounceof my guncotton ; and with half a drachm grms.)a gun sent a bullet weighing three-quarters of an

ounce several inches deep into wood at a distanceof 500 feet. The experiments which I have hithertomade have shown that one pound of guncottonproduces at the very least as much effect as two

pounds of the best gunpowder. I have several timesused my guncotton for blasting purposes in a tunnel 3

1 Eduard Merian-Bischoff, born at Bale in 1824,died in 1859 .

2 He became a painter ; he was murdered at Barbizon nearParis on September 6th

,1893 .

3 The tunnel of the Baden railway near Istein.

AND SCHONBEIN 87

which is being made through muschelkalk in our

neighbourhood,and in the opinion of the work

men it was as effective as three times the quantity of

powder.N0 changes need be made in the guns, cannon, etc. ,

in order to employ guncotton ,and it can be fir ed by

means of the ordinary percussion-caps. Anotheruseful property which it possesses is that it practicallydoes not foul or heat the guns at all , so that severalhundred charges can be fired from the same gunwithout its having to be cleaned.

With the greatest respect,I have the honour to be ,

My dear Baron,

Yours most truly ,

C . F. SCHONBEIN.

BALE,2oth June 1846.

This letter was laid before the Academy on the 9th of

S eptember (the cause of the delay is explained in Berzelius

’answer), together with a communication of the l6th

of August from the second discoverer of guncotton,Prof.

BOttger1of Frankfort on Main, and another fromWOhler

of Go’ttingen,and was printed in the Ofversz

’

gt, Arg . 3

(1846) p. 209 .

1 Rudolph Bottger, born at A schersleben in 1806,died at

Frankfort on Main in 1881 . In August 1846, when professorat the Physical Society at Frankfort, he independently discovered guncotton, and joined with Schonbein in the practicalutilization of the discovery.


Berzelius answered it as follows

B erzelius’

to S chOnbe in

STO OKHO LM,18th November 1846.

DEAR SIR,

The letter of June the 2oth with which

you honoured me did not come to hand till thebeginning of September. Herr Merian

,who was the

bearer of it , informed me that he was to deliver ,along with it

,a packet of specimens of paper from

you ; this , however, he had left at Hamburg, and hewas unwilling to hand over the letter till the box hadcome. But the box had, together with the rest of hisluggage

,been sent to Berlin, whither he intended to

go in a few days . I requested him to deliver it toour minister in Berlin ; this he failed to do , althoughhe made ‘an ascent with the minister in Mr. Green’sballoon . As I also learned from him that you hadgone to England , I deferred expressing to you mygratitude for the information on guncotton till . I

learnt what your address was . I am now sending itto London on the chance of its finding you.

Permitme to convey to you my sincerest congratulations on this interesting and significant discovery ,the practical nature of which you have so promptly


all vegetable matter,especially if the incrustation is

previously removed by moistening it with a solutionof caustic alkali. I have prepared it from Sphagnum

palustre, from oakum ,from straw ,

and , best of all , fromfriable

,decaying wood

,which

,when the humin has

been extracted by alkaline solutions,yields an exquisite

powdery guncotton. The scientific term I proposeto apply to it is lignin nitrate , since a body got fromthese substances cannot well be called guncotton .

I also endeavoured to prepare it from Oladomlce

rangiferina and Uetrarmtslandiea . These , however,contain a framework

,which is composed not of lignin

but of'

starchy filaments,and yields nothing but

amylin nitrate , t.e.,xyloidin . The products of com

bustion of lignin nitrate comprise a gas which I thinkis cyanogen ,

which I certainly had not looked foramong them . I had no time to inquire into the precise elementary structure of this interesting compound ;I disso lved it in caustic alkali , in which it is readilysoluble

,and obtained therefrom saltpe tre , glucinic

acid,apoglucinic acid and other products

,which were

not examined further . My attempts to reproducelignin by means of the exchange of nitric acid forwater failed conspicuously.

"ou would greatly oblige‘

me by favouringme withthe results of your further investigations on the application of lignin nitrate as an explosive.

I have the honour to remain ,

With the greatest respect,Your most obedient servant ,

JAG . BERZELIUS .

AND SCHONBEIN 91

S chonbein to Berz elius

DEAR SIR,

Your kind note of November of last year hasjust been forwarded to me from England , and so Ihasten to thank you most sincerely for it. I learnedwith the greatest interest the results you obtained withguncotton

,especially as I also

,as early as last spring ,

made experiments not only with cotton but alsowith a number of plants

,consisting chiefly of lignin ,

and obtained explosive substances from them .

"ou will have heard that last year,here in Bale as

well as in England , I carried out many experirnents

in shooting and blasting with my guncotton , and Ishould like now to give you some details . In

Faversham in Kent we employed a very accuratelyconstructed mortar , which throws shells of sixty-fourpounds and is used for testing the powder which thefactories of that place supply to the British Government. Two ounces of the best English powder senta shell of sixty-four pounds from this mortar on anaverage 275 feet , whereas an ounce O f my gunco ttonsent the same shell 5 50 feet. In carbines of narrowcalibre 10 grms. of guncotton produced the sameeffect as 41 grms. of the best gunpowder . In pistolsof a particular pattern guncotton exhibited a drivingforce seven twee as great as that O f gunpowder. Imade numerous experiments in blasting in the minesand slate quarries of Kent and in a tunnel in our


neighbourhood which is now under construction ; allgave most satisfactory results

,and in the opinion of

the engineers present proved that for blasting purposesguncotton is preferable to gunpowder. O ne part ofguncotton is under these circumstances as effective asfive parts O f powder. In many instances the guncotton produced eight and ten times as great aneffect as powder. Al though I experimented almos tdaily for many months I have . never had the slightes taccident and not once has anyof the cannons, mortarsor small guns from which many hundreds of shotshave been fired under my direction

,exploded. As far

as my own observations go I have not even observedthat the firearms were perceptibly damaged by theg uncotton I once caused forty shots in successionto be fired from an American carbine

,and after the

experiment it was as clean as before. I find it convenient to saturate my guncotton with a solution of

potassium nitrate,for experience shows that guncotton

so treated is more readily compressible, withoutbecoming perceptibly harder to explode. Possiblythis film of potassium nitrate enveloping. the explosivefi lament . makes it less easy to explode and moreuniform in action. In England they are now makingarrangements to prepare guncotton on a large scale ,and I think that there it will soon be widely used forblasting I and others also have not yet given upthe hope that gun cotton will likewise be applicablefor purposes of War . It is anything but honest ofthe French to continue to claim priority in the

discovery of guncotton on account of Bracconnot’s

AND SCHONBEIN 93

xyloidin as they have for some time done , especiallyas they subsequently admitted the very obviousdifference between the two substances , and as Iprepared gun cotton as early as last year . I had no

desire to assert my claims before the French Academy ,because I am convinced that impartial men of

science will come to a right conclusion on thisquestion .

The last number of Peggendorfi’

s A nnalen containsa few papers of mine , which may interest you inasmuch as they indicate the facts which led me to thediscovery O f guncotton . The resinous substancewhich is formed by the action of a mixture of nitricand sulphuric acids on sugar appears to be a substancequite analogous to guncotton

,and if the latter is lignin

nitrate , the former must be nitrate of sugar . Possiblythe names nitrolignin,

nitrosaccharine , nitroamylin ,

etc . would be suitable for such compounds . Sinceaccording to

"

my view NO 5 does not exist,I con

sider that the compound in question contains N04

combined with an organic substance. The followingfact which I have ascertained appears to be of

especial interest,namely that flowers of sulphur

treated with a mixture of nitric and sulphuric acidsproduce sulphurous acid even at low temperatures .Why is sulphuric acid not formed under these circumstances ? I hold the unusual view that the sulphurousacid formed under these circumstances is a secondaryproduct

,derived from the change of hydrogen sulphide

to peroxide , in a manner analogous to the formationof sulphurous acid by the action of water on chloride


of sulphur. Furthermore it is remarkable thatsulphurous acid brought in contact with the mixtureO f nitric and sulphuric acids is not converted intosulphuric acid

,as takes place when the first hydrate

of nitric acid alone is mixed with sulphurous acid .

I think these reactions deserve the undivided attentionof chemists. That, according to my experience , ozonecombines with iodine , bromine and chlorine to formcompounds very similar to those which these threebodies form with one another, is also a fact whichmay not be without importance.

A few days ago I was most agreeably surprised byreceiving the Vasa medal . His Majesty the King ofSweden has by granting this distinction bestowed onme an honour of which I am hardly worthy

,and for

which I feel myself deeply indebted to him. "ou

would be doing me a great favour if you would kindlylet me know whether I should express my humblethanks for this distinction in a letter addressed toHis Majesty himself.I trust that I shall soon have the pleasure of

receiving a letter from you,and I have the honour to

be,with the greatest respect ,

Your obedient servant ,

O . F. SCHONBEIN .

BALE,12th February 1847.

AND SCHONBEIN 95

B erzelius to S chonbein

STO CKHO LM,12th

DEAR SIR,

“ i f : I thank you sincerely for your courteousletter O f February the 12th and for the interestinginformation which it contains.I congratulate you cordially on the honour be

stowed upon you by Our king. It gave me greatpleasure to hear of it . His Majesty asked me whatshould now be done with regard to your proposal tocommunicate to us for a fixed sum the details of themethod of manufacturing g uncotton

,which has now

been made public . I suggested to His Majesty thathe should grant to the discoverer, whose inventionwas certain to be profitable to us

,some token of royal

favour , for instance the honour O f knighthood . The

king replied that he would consider the matter. A

few weeks later a ceremony of investiture was held,at which you,

however,were not mentioned

,although

several foreigners were named,and so I feared that

the subject had been overlooked , till I was mostagreeably surprised to learn from your letter thatHis Majesty had not forgotten you.

A t the last meeting of the A cademy I submittedyour last letter to them .

9 6 LETTERS O F BERZELIUS

The king happened to be present at the Academy,and to your memoranda added the reports on guncotton given by his ministers from various quarters ,containing among other things a statement that inBrunswick serious disasters had been caused by thebursting of rifles through too powerful a charge of

guncotton.

Like you L. Svanberg1 has prepared compounds of

sugar and gum with a mixture of nitric and sulphuricacids ; they are

,however , not to be compared to

nitrolignin. "ou will observe that I have adoptedyour nomenclature ; lignin nitrate is in fact a misnomer

,for the substance which unites with nitric

acid is no longer lignin,as it has already given up

several atoms of hydrogen and oxygen .

On the other hand I am unable to subscribe toyour views on nitric acid and the nitrates . Theycannot be correct. The test of the truth of a theoryis that it should harmonize the particular instancewith the whole system of science ; for the laws of

nature are always consistent with one another. Now

if‘

you advance a principle which makes an exceptionof what was before consistent with scientific ideas

,

logic pronounces against you; So far as I can judgefrom your paper

, you were led to this by concluding,from the fact that ozone and nitric acid at ordinary

1 Lars Friedrich Svanberg, born in Stockholm in 1805 , wasa lieutenant, then teacher of chemistry and physics at theMilitary College at Karlsberg. From 1858 to 1874 he was

professor of chemistry atUpsala,where he died in 1878.

“ Omsalpetersyrans fOrening med nagra Kroppar,

” Ofversigt, A rg .

4 (1847) p . 5 1.


oxygen is incapable of producing , as the latter onlybecomes active at temperatures at which the organicsubstances are destroyed . The acids I have mentionedalso producelo

'

this effect ; they all give rise to oxygencompounds at low temperatures. This Shows thathydrogen peroxide is not present in nitric acid . The

theory explains the formation of ozone by lightning,

by frictional electricity,and by hydro-electricity .

Its production by means of phosphorus then appearsof a purely catalytic nature , which is quite conceiv

able : whereas it is not conceivable that so readilyoxidizable a body as phosphorus

,which itself absorbs

oxygen ,Should yield so unstable an oxidation product

of hydrogen at ydrogen peroxide. I trust you willexcuse my preaching, and not refuse to learn. Soon

you will find how the Shadows are dispersed by thelight ofjcorrect ideas .Address your letter of acknowledgment to the

Foreign Secretary, His Excellency Baron A . Ihre .

It is quite proper to enclose in it a message in anenvelope , which , however, Should not be sealed

,

addressed to His Majesty the King, and to inquire of

the Minister whether he considers the letter suitableto be delivered to His Majesty. This letter

,however ,

is not essential ; you need only request the Ministerto convey to His Majesty your respectful thanks ;but perhaps it might not be unwelcome to HisMajestygto receive a Short letter from you

Farewel l.Yours Sincerely,

JAc. BERZELIUS.

AND SCHONBEIN 99

XXII

S chonbein to Berze lius

DEAR SIR,

I thank you sincerely for your kind andinteresting letter of the 13th inst. I have followedthe advice you were SO good as to give me and havesent a letter of thanks to His Majesty the King , aswell as to His Excel lency the Foreign Secretary .

Permit me in this matter to express to youmy Sincerethanks for having O btained for me by your goodo

°

ices so honourable a distinction.

I can hardly assent to your and de la Rive’s viewson the nature of ozone

,although I readily admit and

have long been aware that they make it out to bea substance of infinite ly greater interest than itappears according to my theory ; for this reason Iwrote to de la Rive a Short time ago :

“ For

ambition’s sake I must wish that you and Berzeliusare in the right

,and Mr . SchOnbein in the wrong

,

for ozone being mere oxygen modified by electricity,

would be a substance infinite ly more interesting thanmy peroxide of hydrogen .

” 1 My reasons for rejectingyour view are as follows : 1 . Not a Single fact isknown , which Shows that any elementary body ischanged in any way whatever in its properties bymeans of electricity . 2 . O n the other hand there are

a n umber of substances which by combining with1 This sentence is in English in the original—Tr .


oxygen modify it in such a way that it unites atordinary temperatures with many bodies , on whichpure oxygen

,under the same conditions

,has no action.

Such substances are for example HO , PhO ,MnO ,

AgO ,which , when they combine with oxygen

,SO

change it that it decomposes potassium iodide ,converts potassium ferrocyanide into ferricyanide

,

colours guaiacum fesin blue, etc. ; in other words itacts like ozone. 3 . When exposed to the action of

electric Sparks for some time oxygen gas preparedfrom me lted potassium chlorate does , it is true , turnstarch paste

’

containing potassium iodide blue ,and

affects the organs of smell , but it is not , accordingto my experiments , dissolved to any great extentby solutions of potassium iodide or potassium ferrocyanide

,O r oxidizable metals ; and the residual gas

behaves like ordinary oxygen . Now I Should thinkthat a cubic inch of dry oxygen gas if exposed forasufficient length of time to the electric current

,

would be completely ozonized , and thus be entirelytaken up by the abovementioned solutions.4. But infinitesimal traces of water vapour, suchas might be present in oxygen supposed to be dry ,sufice to produce a perceptible quantity ofozone, andso it seems to me that some such view as mine isless improbable than yours . 5 . The destruction of

ozone on heating is readily explained by the assumption that at higher temperatures it is Split up intowater and oxygen, like so many other superoxides,especially Thénard

’

s oxidized ‘water. According to

your view we must assume that heat restores the


of iodine paper are exposed to mo ist atmosphericair saturated with nitrous acid vapours , or suspendedin a flask , the bottom of which is covered with amixture of water and nitrous acid.

I suspect that there exists a compound consistingof N0

24-110

2,which when it comes in contact with

iodine gives up to it its HO,

A ccording to yourview we must assume that when ozonized oxygencombines with iodine

,bromine and chlorine it is as

ozone that it does SO .

With regard to my views on the hydrate of nitricacid

,I venture to maintain that it is by no means

isolated and without analogy , so long as one holdssimilar views on other acids . Anhydrous sulphuricacid for example I regard as SO

,+ O ,the third

atom of oxygen being in a chemically active state ;the hydrate of sulphuric acid I look upon asS0

2+HO 2, and the normal sulphates as SO2+RO Z ;

the hydrate of chloric acid would of course be

0 104+HO 2 , anhydrous iodic acid IO

4+ O etc .

Possibly we might also regard the SO -called firsthydrate of oxalic acid as 2CO +HO , , acetic acid as

C4H4+ 2O or as O

4H3+H0 2. However , I am always

suspicious about substances which cannot be isolatedand which cannot exist except in combination withother substances , such as water and the SO -called saltbases . I am half inclined to fear that the assumptionof these hypothetical compounds has retarded ratherthan promoted the progress of chemistry.

I have taken the liberty of giving you some of myviews on the different conditions of oxygen in the

AND SCHONBEIN 103

pages 1 which I enclose , and of submitting them to

your judgment . Should you consider them in anyway as worthy of your attention , I trust you will bekind enough , when you have an opportunity , to sendme a few comments on them . Finally I must ask

you to do me a great favour. A S the patent whichI have taken out for my guncotton in England wil lundoubtedly be contested , I should be very muchobliged to you if you would state in a letter , in whatever manner you consider most suitable, that it wasI who first discovered and prepared nitrolignin.

Such an expression of your opinion would have greatweight in England, and I have little doubt that youalso will ascribe to me the priority in this matter. Iat any rate consider that I have a full claim to it.With the sincerest hope that your valuable life maybe spared to Science , I remain,

With the greatest respect ,Yours respectfully ,

C. F. SCHONBEIN.

BALE , 29th March 1847.

The letter of Berzelius no doubt suggested to a certainextent a discourse of Scho‘nbein’s : “ O n various ChemicalS tates of O xygen,

” 2 which he delivered on 2 l st April tothe Scientific Club of Baile, and in which he attacks theviews ofMarignac

,de la Rive

,and Berzelius . [cf. P oggend .

Annal., vol. lxxi . (1847 p . 5 17 Where he uses the words

since the great Swedish chemist assails me in writing1 See Appendix. 2 Ibid.


Berzelius does not himself seem to have given any

summary of this work, for the passage in the Jahresbere'

cht

for which treats of this paper, says with respect toScho'nbein’s attempt to draw a parallel between ozone and

chlorine,bromine and iodine

,and thus to represent them

as oxylizations of radicals not yet isolated : “all very

S imilar to views held thirty or forty years ago.

” 2 Berzelius,the faithful adherent of the Murium theory, could not

have written thus . This view of mine is further confirmed by the fact that it can be proved that the report ofScho'nbein’s other work, for instance, on guncotton,3 forwhich , as we have seen, Berzelius evinced so great aninterest

,was no longer drawn up by Berzelius himself, but

by Lars Svanberg. Consequently we may regard as the

last utterance of Berzelius on Schonbein and his work a

passage to be found in the 27th volume of the Jahresbericht,which runs as follows

“ A ssuredly there is at present no chemical investigation so important and so much wanted by the scientificworld as a systematic memoir of the history of ozone in all

its details. Certainlyno workwould yield such unexpectedresults to anyman who had the courage to undertake it inearnest

,and who did not try to avoid the difficulties by

means of vague phrases, ” 4 a practice to which Schonbeinwas certainly not given .

O n a sheet of paper in part filled with a draft of a letterto Faraday which bears the address Rotzberg, near Stansstad

,but no date

,I have discovered the first hasty sketch

of an obituary notice of Berzelius,which

,as the last

remark of Sch '

onbein on his great colleague, maywell have

1 “ Jahresbert'

cht uber die Fortsehrz’

tte der Chemie,continued

after the death of Berzelius by L. Svanberg . Presented to theSwedish A cademy of Science on 3 lst March 1848. [ButBerzelius did not die till 7th August

2 Loc. cit. p . 12 .

3 Loc. cit. p . 342 .

4 Loc. cit. p . 29 .

A PPEND I X

ON VARIOUS CHEMICAL STATES OFOX"GEN

O NE of the most important and interesting branches of

chemical investigation to which it would seem sufficientattention has not been devoted is the influence exertedon the affinity of a substance by the other substanceswith which it is combined. In many cases the same

element in an isolated condition Shows an essentially

different behaviour towards certain substances from thatwhich it exhibits when in combination . In this con

nection oxygen of all simple bodies shows the mostremarkable behaviour ; for according as it is isolated, orin this or that state of combination, it may Show either a

very high degree of chemical activity or none at all.

If I am not mistaken there is no Sing le element withwhich dry Oxygen combines at ordinary temperatures ;but when it is u nited with certain substances its behaviour is wholly different. Contrary to what theoreticalconsiderations would lead us to expect, combined oxygenShows such a degree of chemical activity that even at low

APPENDIX 107

temperatures it forms chemical compounds with a series

of bodies, on which free oxygen under conditions otherwise the same has no action whatever. Among the

substances which by their union with oxygen raise itschemical activity are several oxides of the general formulaRO ,such as HO ,

BbO and MnO . When one of theseoxides combines with a further atom of oxygen bodies areformed which have a remarkable power of oxidation for

example,they expel iodine from potassium iodide , convert

the yellow prussiate O f potash into the red, turn guaiacumsolution blue

,and destroy indigo solution . These com

pounds also resemble one another in their voltaic behaviour ; they possess a remarkable degree of electromotive power

,i.e.

,they are eminently electro-negative .

The peroxides owe all these properties to their second

atom O f oxygen. We must therefore assume that thissecond atom is in an essentially different condition fromthe first. It seems to me that it would be desirable forscience to possess a term to distinguish the chemicallyactive oxygen in such a compound perhaps we might usethe expression oxylized,

” by which I understand oxygenwhich has a tendency to leave the substance with whichit is united in order to attach itself to some other oxidizable body. Perhaps it would also be convenient to use

a Special symbol such as O to denote the oxylized atom of

oxygen in a compound . The peroxides of hydrogen,lead

and manganese would accordingly receive the formulaeHO , PbO MnO .

.

A s is well known,nitric oxide (NO 2) exerts a very

peculiar influence on the two atoms of oxygen whichcombine with it to form nitrous acid. The condition of

the two oxygen atoms combined with NO2is not the

same as that of the second atom of oxygen in the per

108 APPENDIX

oxides mentioned above for anhydrous nitrous acid doesnot act even on readily oxidizable bodies to any great

e xtent at ordinary temperatures,and can sustain a high

temperature without suffering decomposition. However,these two oxygen atoms can without difliculty be con

verted into the true oxylized state by mixing the nitrousacid with HO . I have endeavoured to prove that thehydrate of nitric acid is N0

4HO

Q,and that a compound

o f the formula N02 +HO 2 also exists ; both are formed

on mixing N04with HO ; the water, reducing a part of

the NO4to N0

2,is itself converted into HO

2,and this

peroxide combines partly with N0 4 and partly with N0a ccording to the following equation

2No42110 (No4 (No2

The oxidizing effects which these two bodies produceat the ordinary temperature are

,in my Opinion

,due to

the oxylized oxygen contained in their HO2 ; S ince N0 4

binds HO2more closely than N0

2does, NO 2 +HO 2 is a

more effective oxidizing agent than NO4+HO 2 hence

the former even when diluted with ever so much waterd ecomposes potassium iodide, potassium ferrocyanide, andhydrogen sulphide with the liberation of N0

2,whereas

very dilute nitric acid is unable to produce this effect.A S to chlorine

,bromine and iodine, I regard them,

in

accordance with the older theories, as peroxides of murium,

bromium and iodium,my opinion being that they contain

one atom of oxygen in the oxylized condition, to which

the remarkable oxidizing actions,which these bodies are

capable of producing at the ordinary temperature, mustbe ascribed. Therefore I regard the oxides of murium ,

bromium and iodium as analogous to those of water ,

110 APPENDIX

unite with the oxylized oxygen of the former to form the

peroxide, whereas another portion of the lead oxidecombines with murium oxide to form lead chloride .

Hydrochloric acid, in contact with concentrated nitricacid takes up O from NO

4+HO, being oxidized to MuO ,and this most probably unites with N0

4to form an

unstable compound, which constitutes the oxidizing agentin aqua regia . The action of murium oxide on N0

2HO

differs only in that the evolution of chlorine takes placewith greater case. When electric sparks are passed

through a mixture of gaseous hydrochloric acid and oxygen,

chlorine and water are produced,as is well known .

A ccording to my observations electricity determines thecombination of murium oxide with oxygen

,and the latter

,

by uniting with the oxide,is transformed into the oxylized

state . When a mixture of water vapour and oxygen gasis subjected to the same electrical treatment

,a hydrogen

peroxide is formed, namely ozone,and if the oxides of

lead,manganese

,silver, etc.

,were capable of existing in

the gaseous form they would, when mixed with oxygen,

undoubtedly be transformed into their peroxides on

passing electric sparks through them. Lead hydroxideheld before a point from which electricity is escaping intomoist oxygen or atmospheric air is

,it is true, according to

my experiments,changed into its peroxide ; this is, how

ever,due to a secondary reaction produced by the ozone

which is formed under these circumstances .With regard to the chemical nature of ozone

, the

highest authority on chemical questions now shares theview first brought forward by de la Rive, that ozone isnothing but oxygen modified by electricity, and that itdoes not contain hydrogen. These chemists support theirview by the fact that electric sparks passed through

APPENDIX 111

oxygen, prepared from melted potassium chlorate, produceo zone . I am,

however, unable to assent to this view forreasons which I have explained elsewhere, chiefly becausethere is not a single fact to Show that electricity is capableof changing in anyway the chemical properties of any

e lementary substance whatever. If oxygen is capable of

undergoing so extraordinary a chemical change under theinfluence of electricity

,this is a case perfectly unique, to

which there is not even the remotest analogy to be foundin the whole sphere of chemistry. O n the other hand a

large number of cases are known which prove conclusivelythat oxygen

,when united to certain substances, acquires

so great a degree of chemical activity that it oxidizes evenat ordinary temperatures, and this analogy, it seems to me,is more in favour of my theory as to the nature of ozone

than of those proposed by others . Therefore I am firmlyconvinced that the assumption that oxygen prepared frommelted potassium chlorate still contains traces of water isless bold than the view that ozone is an allotropicmodificat ion of ordinary oxygen. A S I have already stated

,I Shall

give up my theory and accept the one which I now

dispute so soon as anybody succeeds in transforminginto ozone by means of electricity a single cubic inch of

really dry oxygen. However, I may be wrong, and the

view of Berzelius and de la Rive may be correct. In

that case we should have to assume that the oxylization

which a number of substances can produce in oxygenby combining with it can also be produced by electricityalone, and furthermore that

,for example

, the second

oxygen atom of the normal peroxides exists in thesecompounds as ozone

, or that ozone and oxylized oxygenare one and the same substance . Then we Should havealso to assume that heat could

,under suitable conditions

,

112 APPENDIX

reconvert oxylized into ordinary oxygen,since isolated

ozone is changed by heat into ordinary oxygen just asthe peroxides are reduced to the oxides under the sameconditions

,the oxygen,

thus separated,appearing in its

normal condition, and as the first hydrate of nitric acidsplits up into NO

z,HO and O . The separation of a

portion of nitric acid would in that case be due to the factthat only a definite amount of ordinary oxygen is capableof uniting with H

,Pb

,Mn

,etc. If 0 in PbO is con

verted into 0 by the action of heat,then the oxygen

would split off, for PbO can remain united with 0 butnot with O . A ccording to the nature of the compoundRO ,with which O is combined, it requires a smaller or

greater amount of heat, to effect this change of O into 0 ,

or its separation from RO .

In the case of HO this change takes place at moderate

temperatures, whereas lead peroxide requires a greater

heat and MuO a still greater.A s far as chlorine, bromine and iodine are concerned

regarding them as peroxides— the highest temperatureswhich we have as yet succeeded in producing are as

incapable of changing their 0 into 0 as they are of meltingcharcoal or O f decomposing a substance which is not a

compound. If,however, these peroxides are mixed with

substances which combine either with their oxide or with

their oxylized oxygen,then the decomposition takes place

with the greatest ease .

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· 16 letters o f berzelius transl ation o f b erzelius’ t extbook. the publisher could not...

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