scottish schools science equipment research centre · 2019-07-12 · introduction we have just sent...
TRANSCRIPT
a
SCOTTISH SCHOOLS SCIENCE
EQUIPMENT RESEARCH
CENTRE
Bulletin No. 80. May, 1975.
Contents
Introduction — basic and workshop equipment list Page 1.
Biology Notes — disinfectant s 1.
In The Workshop — flask shaker 6.
Address List 10.
Bulletin Index, Nose 70 — 79 11.
4
Introduction
We have just sent to all our U.K. readers a copy of our basicand workshop equipment list. The list purports to cover the needsof any science laboratory whatever subjects may be taught there, anddeals with such items as burners, clamps and stands, test—tubes etc.In the workshop section vie have placed items, mainly expendable,which would normally be kept in the technician’s store and drawn fromas needed It includes things like glass tubing, mains cable,crocodile clips. Also in the workshop list we have included arepresentative list of what vie think is required by way of wood,plastic and metal, together with glues, paints etc. if the technicianis to be employed in the maintenance and repair of equipment, or in theconstruction of new designs of apparatus.
The list was priced in November, 197L, which is why it carriesthat date, and, to give some idea of the cost then of equipping alaboratory from scratch, the total cost of the items on the list,taking the lower of the two quoted prices where this is applicable,is as follows.
Basic equipraent £560.
Workshop equipment £830.
Workshop materials £250.
The figures are not exact but have been rounded up to the nearest £10•What they mean is that at the prices ruling at the time, it wouldhave cost an authority £1 ,1 00 plus £560 per laboratory designed for20 pupils to instal the basic equipment. To this must be added theequipment required for Integrated Science, or for the separatescience subjects.
Although the list has been sent to UK. readers only, we willsupply anyone from abroad who wishes a copy, on receipt of 15p (orthe equivalent in their own currency) with a clearly printed addressto which the list should be sent The same charge, which includespostage, applies to anyone in the U.K. who is not on our addresslist, or to anyone wishing additional copies.
Biology Notes
In Bulletins 71 and 7L1. there was seine discussion of the problemof plastic Petri—dish disposal. If our information is correct,some teachers are solving the problem in a potentially hazardousmariner It would seem that they may be soaking used dishes in Lysol,washing them in soapy water, and then re—using them for non—microbiological iiork — as storage containers, crystallising dishes etc.It cannot be emphasised too strongly that treatment with Lysol doesnot sterilise the dishes ysol, in common with other phenolicsolutions and derivatives, is not sporiciclal and any dishes washedin it, may well remain contaminated. Used dishes should be disposed of
—2—
by the recommended methods. There is, as far as we are aware, noreliable way to ensure that dishes are completely sterilised exceptby autoclaving or some other form of heat treatment, after which theyare in no state to be re—used, If teachers are upset by the wasteof material and environmental contamination inseparable from the useof plastic dishes, they can always join with a number of theircolleagues who have returned to using nom—disposable, but highlybreakable glass Petri—dishes,
The misuse of Lysol has lead us to consider the general problemof disinfection, A large number of different chemicals can be usedto kill or control micro—organisms. Their action can be fungicidal,bactericidal — killing bacteria but not necessarily their spores,virucidal, sporicidal, or germicidal. The last is strictly, amisnomer, A germicide kills almost all micro—organisms, there beingno known liquid germicide which is completely effective against allorganisms. Some chemicals act merely as bacteriostats, preventingthe growth of bacteria without necessarily killing them. For schoolusage the choice of disinfectant has to be made after consideringseveral factors. The most important and most obvious of these isthat the chemical(s) used should be known to be effective againstthe organisms involved, under the conditions likely to be encountered.For example, it serves little purpose to use a non—sporicidalcompound which is inactivated by the presence of organic matter whencleaning cages. Another important consideration is that thesubstance used must not be harmful to the user or to livestock.Toxic preparations and, as far as this is possible, those which actas irritants, should not be used in schools. Lastly there is theissue of cost. This involves two factors, the price of the liquiddisinfectant itself and the normal working concentration, which willdetermine the actual cost per unit volume of disinfectant solutionas used in the laboratory. When making up dilutions from concentrated disinfectants it is advisable to use distilled or freshlyboiled water, so lessening the risk of any contamination withresistant organisms. Bottles used to store the diluted solutionsshould never be fitted with corks, as these can inactivate manydisinfectants,
The table below summarises some of the relevant information onthose disinfectants encountered in laboratories,
Action. Recommended Use Dilution.
B — bactericidal D — dirty equipment, cages etc.
Bs — bacteriostatic G general disinfection of
F — fungicidal‘clean’ glassware, equipment etc.
V — virucidalI — instruments
Tb — effective against— sicin disiifection
tubercle bacilli
— S ri dal C — swabbing of ‘clean’0 Ci surfaces, hard floors etc.
hd — at high dilution
Dis
infe
cta
nt
Appro
x.
cost
per
Acti
on
Rec
om
men
ded
uses,
No
tes
litr
eof
work
ing
toxic
ity.
so
luti
on
and.
work
ing
concentr
ati
on
(v:v
aqueous
solu
tio
n).
?och
lorit
es
‘On
loro
s’S
olu
tio
ns
G,
CG
ood
for
genera
lm
icro
—bio
logic
al
co
nta
inin
gat
use.
Irrit
an
t,corr
osiv
epr
op—
‘Lil
ton’
Iple
ast
20
0B
,S
p‘°
Serti
es
mea
nuse
isrestr
icte
dto
p.p
.in,
avail
—b
d.i
sin
fecti
ng
cle
an
gla
ssw
are
,M
aws
‘Sim
pla
’able
ch
lori
ne
mer
nran
es
sp
illa
ges
and.
pre
—tr
eatm
ent
of
sho
uld
be
used.
orrosiv
eo
mate
rials
Pri
or
todis
posal.
meta
l,sh
ou
’dH
eavy
conta
min
ati
on
wit
ho
rgan
icno
be
use
don
matt
er
mea
ns
usin
gsolu
tions
wit
hI
to20
avail
able
ch
lori
ne.
Ble
ach
ing
acti
on
pre
clu
des
use
on
Vic
arpro
tecti
ve
glo
ves.
clo
thin
g.
?lc
ohols
Eth
anol
.7
5i
5k,
I(m
oo.
Use
usuall
yrestr
icte
dto
mic
ro—
,—
—lo
ops).
bio
log
y—
as
aero
so
ls,
swab
bin
g,
,,
,
ce
ing
.Loo
psS
pr1S
25p
1:lto
B,
Tb
Som
eris
of
etc
.U
sed
todis
infe
ct
skin
(Indastr
ial
I2
.5.1
toxic
ity.
befo
reta
kin
gb
ioo
sam
ple
s.sp
irit
s)
Poenti
al
fir
eA
cti
vit
yre
du
ced
inp
resen
ce
of
zar
org
anic
matt
er.
No
tsp
ori
cid
al.
Phenoii
cs
‘Lv
so]i
to1
10
0to
B,
F,
To
xic
,ir
rit
ant.
No
longer
reco
mm
ended
for
school
(cre
zo]/
soap
21
•2
0B
s(h
d),
Pote
nti
all
yvery
labora
tory
use.
Com
pati
ble
wit
hm
ixtu
re)
p•
V1hazard
ous
inth
eso
ap
but
not
fats
or
oil
s.
Not
undil
ute
dsta
te.
sp
ori
cid
al.
1.
Dis
infe
cta
nt
Ap
pro
x.
cost
per
Acti
on
Reom
mended
uses,
Note
sli
tre
of
work
ing
tox
icit
y.
so
luti
on
an
dw
ork
ing
co
ncen
trati
on
(v:v
aqueous
so
luti
on
).-
Solu
tions
wit
hM
aybe
use
don
cages
but
pla
sti
cs
25
—150
p,p
.m.
and
rub
ber
can
ab
sorb
much
of
the
avail
able
G,
I,
C,
avail
able
iodin
e.
Corr
osiv
eto
iodin
e;
up
toB
,S
p,
Rela
tively
non—
meta
lat
hi&
co
ncentr
ati
on
s.
Colo
ur
indic
ate
sle
vel
of
‘Wes
cod
yn
e’l—
2p
10
00
p.p
.m.
inF
,T
b,
irrit
an
tir
use
dare
as
heav
ily
V.
acti
vit
y.
Not
gre
atl
yaff
ecte
dco
rrectl
y.
conta
min
ate
db
ych
ang
eo
fpH
or
org
anic
wit
ho
rgan
icm
att
er.
matt
er,
guate
rnary
_A
mm
oniu
mC
opounds
(QA
Cs)
‘Task
’D
o1
10
0D
,S
k,
G,
C.
Acti
vit
yre
duced
by
org
anic
matt
er
9,
.A
cti
ve
film
‘eft
on
treate
d‘s
av
ion
’8k,
G,
C;
Vir
tuall
ysurf
ace,
Com
pati
ble
wit
hm
eth
ax-a
lli
quid
0W
flto
B,
non—
toxic
at
and.
alk
ali
s,
not
wit
hanio
nic
sor
anti
septi
c1
20
0or
Bshd,
wo
rkin
gle
ss
dep
en
d-
Tb
hd
,concentr
ati
on,
soap
s,
Oft
en
mo
reacti
ve
again
st
ig
ram
+v
ety
pes
but
pre
para
tions
‘Savio
n’
ing
on
cir
cm
—S
1in
sensit
iz—
wit
h‘H
i.bit
an
e’
are
more
acti
ve
hospit
al
sta
nces
an
dati
on
and.
co
ncen
trate
indiv
idual
irrit
ati
on
ag
ain
st
gra
m—
yeorg
an
ism
s.N
ot
spo
ricid
al,
‘Ase
pto
po
l’pro
duct,
report
ed
but
no
tco
mm
on
,
holytes*
Goo
dall
—ro
und
dis
infe
cta
nt.
‘Teg
oM
HG
’1
pD
,G
,I,
Sk,
C•
Usefu
lfo
rcag
es
etc
.C
ompa
t—B
,B
a,
Vir
tuall
yib
lew
ith
man
ysurf
ace
acti
ve
‘Gri
ffin
AS
AB
’3-
1100
F,
Sp
,non—
toxic
and.
agents
,in
clu
din
gQ
AC
s,b
ut
not
Tb.
no
n—
irri
tan
t,w
ith
soap.
Leaves
acti
ve
‘Harr
isB
AS
’3p
su
rface
film
;d
eo
do
risin
g;
.acti
vit
ynot
reduced
by
org
an
ic
[_
__
__
__
__
__
__
__
__
_—
4:-
F.
*pio
1ic
s.
‘Ly
sol’
isth
ephenoli
cpre
para
tion
most
com
mon
lyen
co
un
tere
din
school
labora
tori
es.
Wh
ilet
we
ad
vis
eag
ain
st
the
use
of
Lyso
l,so
me
pre
oara
tions
co
nta
inO
fli
the
hiier
phenoli
cs
an
dare
less
irrit
ati
ng
and
tox
icT
he
main
advanta
ge
of
such
dis
infe
cta
nts
isth
eir
rela
tive
cheapre
es
an
dth
ere
ten
tio
no
facti
vit
yin
the
pre
sen
ce
of
org
an
icm
att
er.
We
would
not
rule
out
their
use
inso
me
sit
uati
on
s,
e.g
.fl
oors
,fo
otp
ath
san
d.oth
er
larg
edir
tyare
as,
**
Am
r.o
lyte
s.
Th
ese
are
&iC
Oacti
ve
ag
ain
st
som
ev
iru
ses,
part
icu
larl
yth
ela
rge:.
po
xty
pes,
e.g
.anim
al
pox
vir
uses
There
isso
me
co
nfs
ion
betw
een
lab
ora
tory
ani.
fie
ldtr
ial
result
sas
toth
eeff
icie
ncy
of
acti
on
ag
ain
stoth
er
vir
uses
and
there
fore
we
hav
en
ot
descri
bed
these
com
pou
nd
sas
bein
gvir
cid
al
alt
ho
ug
hth
ey
do
sho
wco
nsid
era
ble
anti
—vir
al
acti
vit
y.
+Jd
ed
fs,
meth
ara
lsciu
tio
no
nfil
ter
paper
can
he
use
dto
pro
vid
em
eth
ans.
].vapour
tok
ill
icro
—o
rgan
isis
inP
:tri
-dis
hes
by
treatm
en
tovern
ight
befo
rein
spscti
sn
of
cult
ure
sby
pupil
s.
Ho
wev
ersu
ch
inspecti
on
isra
rely
necessary
and
ifatt
em
pte
dth
epro
cedure
reco
mm
ended
by
M,I
,S,A
0C,
should
he
foll
cw
ed
(School
Scie
nce
Revie
w,
No
,1
95
,(M
I.S
.A,C
.M
icro
—b
iolo
gy
inS
chools
Ad
vis
ory
Co
mm
itte
e;
nam
esand
addre
sses
of
.oca]
ad
vis
ers
inS
cotl
and
are
giv
en
inth
eJourn
al
of
Bio
log
ical
Educati
on,,
1,
Febru
ary
,1
97
5.)
,
I
Dis
infe
cta
nt
Ap
pro
x.
cost
per
Acti
on
Rec
om
men
ded
uses,
No
tes
litr
eo
fw
ork
ing
toxic
ity,
so
luti
on
an
dw
ork
ing
concentr
ati
on
(v:v
aq
,ueo
uss
olu
tio
n),
Ch
ioro
xy
len
ols
‘Dett
ol’
5p
8k,
I;1:
20
Bk
,G
,r
‘G
ood
for
use
inre
lati
vely
,‘.
Jo
‘cle
an
’are
as,
Acti
vit
yB
ootB
’Fam
uly
2p
G;
1L
0B
,L
ittl
eto
xic
ity,
reduced
inpre
sence
of
Anti
septi
c’
Can
be
irrit
ant
‘IZ
S.i
whe
nu
nd
ilu
ted,
org
anic
matt
er,
Anti
septi
c’
1C
;1
150
Meth
anal
Usu
all
y1
50
B,
Be,
Hig
hly
irrit
ant
Not
reco
mm
ended
.fo
rsc
ho
ol
use
(Form
ald
ehyde)
Ip
toI
:2
0F
,S
p,
and
toxic
,V
apou
rbecause
of
toxic
ity
and
V.
may
com
bin
ew
ith
irrit
an
tp
rop
ert
ies,
hydro
chlo
ric
acid
vapour
tofo
rma
carc
inogen,
-—
—6—
Local wharmacists will usually be able to supply Dettol, Boots FamilyAntiseptic, Izal ntiseptic, Chioros, Milton, and Maws Simpla. Othersuppliers are; Tego MHr — Houh, Hoscsaon nJ Co.; G-riffin A0’B —
Lifn.n anI Gcorp-e, Harris BaD — Philip ILrrlD Biological, Task andAseptopol — British Hydrological Corsorstion; Savlon products — 1.0.1.Wescodyne — Ciba—Geigy.
In The Workshop
The origin of this design caine from the Berwickohire High school,Duns. The use of an oscillating shaft in a flask shaker is not new;it features for example in the Griffin and Gcor version. Wherewe have departed from custom is in the method of linking the shaftto the drive mechanism. The usual connecting link system couplesthe shaft to the drive permanently. We have noticed that on soniccommercial versions this tends to move the liquid bodily, whichproduces relative motion and presumably solution between the liquidand any heavy particles lying on the bottom of the flask, but doeslittle for any that are in suspension. Vie decided therefore thatwe would use the drive only to displace the shaft from itsgravitationally stable position, and use gravity to effect the returnof the shaft for the next strokes This produces a jerky motionwhich really shakes up the material in the flask; in foot we havefound that if the stopper is not secure it can be snL’kun loose andthe liquid spilt. At the same time we built in a q.uick method ofadjusting the degree of shaking by varying the amount of displacementof the shaft• The principles will be seen in Fig. 1
At one end of the shaft carrying the flasks is keyed a long pin,
like a knitting needle, which projects downwards. iear base levelthis is in the path of two projecting pins sited on a disc which isturned at a speed of about one revolution per second by a motor.Each pin in turn impinges on the needle and moves it to one side.
lIon the rotation of the disc carries the pin beyond the end of theneedle, the weight of the flasks causes shaft and needle to drop backuntil the needle strikes the second pin. This sudden arrestinent oftIi return produces the jerky motion, and turbulence of the flaskcontents. The position of the needle on the shaft relative to the‘rest’ position of the flasks may be altered, moving it to one orother side of the vertical, and this produces more or less vigorousshaking.
The oscillating shaft is a piece of oak or other hardwood,300 x 25 x 25 mm On each of the sides are screwed three Terryclips to hold the flasks, six of size Li. and six size 3 in all.The size L clip will take a 250 ml conical flask, while size 3 fitsthe necks of 250 or 350 ml round flaaks• The clips are not scrusuddirectly to the shaft; instead, small pieces of wood, used solelyas spacers so that flasks on opposite sides of the shaft will not bein contact are placed imdei’ each clip. Pieces of hardboard wereused under the size Li. clips, arid of 5 mum thick plywood under thesize .3 clips. Also, to avoid we:iiening the shaft by having four
—7—
screws entering at the same cross—section plane, the placings of theclips on the four sides of the shaft are offset by a small amountrelative to each other. Clips on the same side of the shaft areabout 10 cm apart. For balance the same size of clip and flaskmust be put on opooite sides of the shaft. The capacity of theshaker is therefore six flasks of the same sizes If only one flaskrequires shaking, it must be balanced by a similar water—filledflask on the opposite side•
At each end of the shaft a 10 mm dia. hole is drilled 25 mmdeep. Into these are fitted two lengths of 10 mm dia, mild steelrod, so that they project 25 mm at one end, and. mm at the other.In our case these were secured with Araldite. These rods supportthe shaft on two L brackets, made from 6 x 25 mm mild steel bar, sothat it is about 18 cm above the baseboard. Two nylon bushes areused between the rod and brackets. Details of this part of theconstruction are shown in Fig. 2.
The drive mechanism fits on to the longer of the two rods, andis shown in Fig. 3. It is made from mild steel rod, 25 mm dia.,turned down on the lathe to 20 mm dia. at one end. The driveneedle, which could well be a steel imitting needle, in our case wasa length of 3mm mild steel rod brazed into the bush to a depth of 5 mm,The length of the needle is about 15 cm; it should be made so thatthe end is level with the drive shaft of the worm gear. One or moreAllen type grub screws are used to lock the bush onto the shaft ofthe shaker, The end 20 mm of the needle is covered with a lengthof polythene or polypropylene tubing, largely to reduce noise fromthe drive pins striking the needle. Thus when the grub screws areloosened, the position of the needle on the shaft may be adjusted sothat the needle is in contact with the drive pins for only a smallfraction of the rotation, producing gentle shaking, or over almostthe whole of the rotation cycle, giving more vigorous shaking.Again, when changing from one size of flask to the other, the screwsare loosened and the shaft turned through 9Q0
The motor drive is shown in Fig. L4. Two 25 mm long Li- BA boltsare fixed LO mm apart and diametrically opposite on a Li-5 mm brassdisc which has been silver soldered to a brass bush suitable forfitting the motor shaft, The bolts are covered with nylon tube,again to reduce noise and for good wearing. These sleeves are aloose fit on the bolts so that they rotate when in contact with theneedle, Any motor which will provide the necessary torque and. run.continuously will be suitable. A final speed of one revolutionper second indicates that one with a worm gear may be best. Amongstour surplus material we have a motor of this type, in sufficientnumbers to be able to offer it to any who wish to construct the flaskshaker, Unfortunately it is designed for intermittent use at 115 Vand requires additional components to be bought to adapt it for 2Li.0 Vcontinuous running. Despite this we think that it is still possibleto construct a cheap and effective flask shaker using the motor.The remainder of this article will therefore deal solely with theadaptations necessary to use our motor with the shaker,
The package as supplied — cost 50p plus postage — will consistof !otor, Li—terminal connecting block, starting capacitor, and wormgearing. The following additional components will be required.
—8—
Auto_transIormer, K. R, Whiston 5107 £1.6221j.0/115 V
Toggle switch R,3, Domponents 31—563 26pFuse holier )t12—021 2p500 mA fuse .1L12—138 ipPower resistor, 15Li—)38 2lp
0.7 A
An alternative auto—transformer is the R,S. Components 207—116 at£2.70. The electrical circuit of the mtor is shown below,
— —- I
:Connections to the right of the lotted line will normally have
been made on the ecuipmcnt as supplied by us, although in caine casesthe earth connection to the motor may be riiseing, There are anumber of screw holes in the motor case to which this connection maybe made• The colour—coded leads between the motor and the connectorblock are B/0 = black/orange; Bl = blue; B = black. The auto—transformer leads have standard coding on both primary and secondary,i.e. brown = live; blue = neutral; green/yellow = earth. The powerresistor was included in the motor input to reduce energy dissipationso that the motor, even when boxed in, would run continuously withoutoverheating, It has the same beneficial effect on the transformer,and it does not affect the performance of the motor. Using theresistor, the p.d, applied to the motor ic about 100 V and thecurrent 0.5 A,
The motor shaft is threaded for a worm drive • The worm gearinsupplied consists of a worm wheel on a shaft and two other connectedgear wheels, all on a U—bracket. The gearwheels are not needed and.should be removed. One is fixed to its shaft with a circlip, the.other is secured by a pin through the wormshaft which must be pulledor hammered out. A spacer, also pinned on the worm shaft shouldalso be removed. The worm wheel is fixed to the shaft with anAllen grub screw; this should be loosened and the vtheel moved sothat it is at the end of the shaft. This allows the shaft to bepushed further into the U—bracket so that its far end projects I’arenough beyond the bracket for the attachment of the brass disc ofFig. J4., The worm shaft is 6,L1. mm (* in) diameter, and thedimensions given in Fig, L should fit it, It will be necessary todrill two holes in the base of’ the bracket to allow it to be screweto the baseboard. Fig. 5 shows the find appearance cf the wormdrive,
Our base was a pieee eJ 20 mm biocdioard measuring 60 x 25 cm,This is large enough to contain the shaker, the motor, and itsassociated circuitry, We think that the motor is powerful enough todrive a total of’ 8 250 ml flasks, I’uUI’ to a side, and if this wereIoiie the btseboard and. usciilating shafU eould ruu1L’u to be lenjt’—
w1 - ‘e mae a eovr t’or a1 1 i ‘iv ng i1iacian xe pt t1nLsc .iitl (iLiVe T]-, U31fl r.’ mild ti-_l. This
• bs4
0 —9—
serves the double purpose of insulating pupils from contact withhigh voltages, and protecting the equipment from spillages from theflasks. The cover carries the switch and fuseholder at one side,but all other components are mounted on the baseboard. Theremaining sides of the cover have gauze—covered vantilation holesand it was also painted matt black to help heat dissipation. Infact none of the components runs so hot as to be uncomfortable to thetouch. After all components have been mounted the baseboard andL—brackets should be given a protecting coat of varnish. To dateour shaker has run continuously for six weeks with a load of six250 ml flasks each containing approximately 150 ml water.
\ S \\‘\
[S
former shaft wormnot required I
Lt
200
1.
Fig. 2.
ft\ f\
needle
Fig.
Figures not to scales
_______
Dimensions in mm.
/
VFig. 5.
rHil
7 77 757 V(D
________
-
‘—5---’-
—‘
L1
h.p
— 10—
S.C.S.E.R.C., 103 Broughton Street, Edinburgh, EHI 3RZ.Tel O51 556 218L.
British Hydrological Corporation, Colloidal Works, Deer Park Road,London, SWI9 3UQ.
Ciba—Geigy (UK) Ltd., Agrochemical Division, Whittlesford,Cambridge, CB2 LQT.
Griffin and George Ltd., Braeview Place, Nerston, East Kilbride,Glasgow, G7L 3XJ.
Philip Harris Biological Ltd., OicLrnixon, Weston—super—mare, Avon.
Hough, Hoseason and Co. Ltd., Levenshulme, Manchester, M19 3PT.
I.C.I. Ltd., Pharmaceuticals Division, Alderley House, AlderleyPark, Macclesfield, Cheshire.
R.S. Components Ltd., P.O0 Box L27, 13 — 17 Epworth Street,London EC2P 2HA.
K. R. Whiston, New Mills, Stockport 12 4PT.
Bulletin Index, Nos. 70
Accidents in laboratories 70,5; 79,5.Ammonia, combustion in air 72,10.Ammonia, decomposition by sparking 70,l-j-.Ash content determination 71 ,7.
Blowpipes for natural gasBridge rectification model
Calculators, test reportCalculators, test summaryClinistix test stripsCollapsed can experiment, using ring—pull cans
Didacta exhibitionDiluter for disposal of liquid wastesDispenser for constant volume of liquidsDissolved oxygen measurement
Electrical components testerElectronic calculators, test reportElectronic calculators, test summaryElectrostatic field demonstrationEquilibrium constant of lead sulphate/sodium iodide
Flameproof cabinets tests 75,2; 78,6.
Gas lighters, natural and town gasGas lighters, test summaryGlass tubing, how to abrade with wire gauze
Hazardous chemicals, disposal ofHeats of neutralisatjon
Integrated Science equipment listIntercostal muscle model
Lever apparatus designLung contamination, smoking doll desi
—11 —
79.
71 ,3.77,6.
70,7.70,9.71 ,6.78,6.
73,2.73,7.73,9;78,3.
71 ,1.70,7.70,9.71 ,278,11.
7L., 9.
7L1. , 77L1,1 1.77,11.
70,171 ,5.
7L,177,10.
75,11.73,1 0.
76,3; 77,2.76,9.76,5.7L, 6.72,11.79,179,6.79,8.
Melting point apparatusMethane substitution molecule modelMicro—biology hazardsMicro—biology kit, GriffinMicroscopes, test summaryMillon’s reagent, haza.tlds and alternativesMolecular weight of gases determinationM alt i—vibrator design, using integrated circuit
pH electrode simulator designpH meter modified for demonstrationPaper chromatographyPeak and r.m.s. values of alternating currentPelican crossing sequence modelPen recorder as a timing devicePhoto-micrographyPrecipitate washing, automatic
Resistance wire former 75,10.
SYS alternating current experimental guide,correction
Silver recovery methodSodium street lamps as spectrum sourceSoldering iron design for battery operationSciuare wave oscillator using integrated circuitStethograph and tambour designSurplus ecuipment
Test summary, electronic calculatorsTest summary, gas lightersTest summary, microscopesThermo—chromic liquid recipeThermo—electric effect apparatus designThermometer life—saverTicker tape dispenser design
72,1.73,7.79,7.72,8.79,8.75,14.72,8; 714,2; 77,3.
70,9.714,11.72,11.70,5.76,8; 77,6.75,10.79,10.
— 12 —
78,1 0.75,8.76,14.77,8.72 , 2.70,2.73,14.76,14.
Velocity of sound in a metal rod 76,5w