SCIENCE-ADVERTISEMENTS

- ieceat ~ ?c~dce~a~9 & WM-

LABORATORYPRACTICE OFORGANIC

CHEMISTRY

Revised Edition

By G. ROSS ROBERTSONUniversity of California

The unusually full and clear discussionof theory which distinguished the firstedition of this text has been further clari-fied and expanded in this new edition.The 70 experiments in the second part ofthe book allow for considerable choice,and cover thoroughly all important topicsin organic chemistry. Among the manyexperiments added in the new edition areabout a dozen entirely new ones, notfound in other comparable manuals, whichoffer both teacher and student a refresh-ing change from the routine work. $2.50

INTRODUCTORYGENERALCHEMISTRY

Third Edition

By STUART B. BRINKLEYYale University

A complete revision along the lines of thelatest revision of the author 's " Principlesof General Chemistry" brings this textup to date. This book has been especiallypopular for classes of students who havehad no previous training in chemistry inhigh school or preparatory school. Whileit is a little less rigorous than the " Prin-ciples " text, it is very thorough andmaintains the same high standards ofscientific exactness and clarity which char-acterize Professor Brinkley's other work.Ready in the summer. $3.50 (probable)

TEXTBOOK OFQUANTITATIVEINORGANICANALYSIS

Revised Edition

By KOLTHOFF & SANDELLUniversity of Minnesota

This text, long noted for its comprehen-sive and thorough treatment of quantita-tive analysis, is now brought completelyup to date. Among the many new im-provements are the extensive discussionsof modern abridged spectrophotometryand errors in analytical chemistry; a com-plete list of oxidation-reduction indicatorswith oxidation potentials; and compre-hensive discussions of electrometric titra-tions and the properties of precipitates,coprecipitation, post-precipitation and ag-ing. $4.50

FUNDAMENTALPRINCIPLESOF PHYSICALCHEMISTRY

By PRUTTON & MARONCase School of Applied Science

Every part of this new basic text in phys-ical chemistry is evidence of the authors'complete knowledge of their subject. Itis clearly written and extremely thoroughin all fundamentals. Thermodynamics isintroduced early and used throughout.The whole book contains the most recentinformation, including an unusually fulltreatment of the important principles ofelectrochemistry. It includes 454 origi-nal problems. Ready in the summer.$4.50 (probable)

- 74e W*a .60 *4 dce#aeA. lterm _ -

APEDL 21, 1944 9

SCIENCE-SUPPLEMENT VOL. 99, No. 2573

SCIENCE NEWSScience Service, Washington, D. C.

THE CHEMICAL TREATMENT OF WOODSOFT woods become harder than hard maple and maple

wood is made harder than ebony by a new chemicalprocess announced by Dr. J. F. T. Berliner, of the E. I.du Pont de Nemours and Company. It is a developmentby chemists of the company following a line of researchthat paralleled studies conducted by the Forest ProductsLaboratory of the U. S. Department of Agriculture.

This process makes timber markedly harder, stronger,stiffer and more durable, it is claimed. The naturaltendency of wood to swell, shrink or warp with changesof humidity is eliminated. Furniture, for instance, madeof the transmuted wood can be shipped throughout theworld, to tropical jungles or arid deserts, and will remainin condition. Color may be imparted permanentlythroughout the material by the use of dyes in the im-pregnating material.The chemical agent used in this new process is called

methylolurea and is made by compounding urea withdimethylolurea. Both these materials are white, water-soluble solids, produced from ammonia, carbon dioxideand methanol, more commonly known as methyl alcohol.Urea results from the reaction of ammonia and carbondioxide. Formaldehyde, derived from methanol, con-

denses with urea to form dimethylolurea. Both urea anddimethylolurea are inexpensive chemicals available com-

mercially.The methylolurea is impregnated into the wood in a

water solution. It reacts with the components of woodto form hard, water-insoluble, unmeltable resins withinthe piece of timber being treated. Heat, such as kiln dry-ing, speeds the process.

The treatment can be used also to harden the outsideportion of a piece of lumber without affecting the interior,obtaining results somewhat similar to those obtained in

case-hardening steel. This treatment will be found de-

sirable for certain types of construction such as trestles,bridges and towers.

ITEMSHWA LO-KENG, a self-taught Chinese mathematician, is

coming to the United States to lecture at the invitation of

Dr. Albert Einstein, professor in the Institute for Ad-vanced Study at Princeton, N. J., according to reports tothe Chinese News Service. Professor Einstein is starting a

series of lectures on unsolved problems in mathematics byauthorities from various parts of the world. Both he andMr. Hwa will serve as directors of the program as wellas lecturers. There will be a total of four such directors.A native of Kingtai in Kiangsu Province, Mr. Hwa isthe author of eight dissertations in his field. His two

published theses on much discussed but unsettled mathe-matical problems have aroused great interest among themathematicians of the world.

QUARTZ filaments, so fine that it would take 60 of themto make the thickness of a human hair, are drawn out in

production in a relatively new method by use of a bowand arrow at the Westinghouse Research Laboratories at

Pittsburgh. These superfine filaments are for use in theelectron microscope to measure or calibrate its magnify-ing power. The bow, made of tough flexible steel, ismounted on a wooden stock. The arrow is shot out alonga groove in the stock. In action the cross-bow is placedin firing position and a small cylindrical piece of quartzattached to the rear end of the arrow. The quartz isheated by an oxy-hydrogen torch until it is just ready tomelt. Then the arrow is released, trailing behind it threadsof quartz sometimes 20 feet in length.

DR. GUSTAV EGLOFF and Mary Alexander, of the Uni-versal Oil Products Company, reported at the Clevelandmeeting of the American Chemical Society that when themotorist of the future talks of how much mileage he getsout of his "gas," he may be using the word literallyrather than as a shorthand term for gasoline. Under thenecessities of war, more than 165,000 automobiles, mostlyin Germany, are using gaseous fuels. Even in this coun-

try, some 25,000 buses, trucks and other heavy-dutyvehicles employ gases for fuel. All the automobiles inthe United States could run, if necessary, on methane(marsh gas) obtained from natural gas, petroleum refin-ing and coal processing.

PHOTOFLASH lamps are satisfactory for the illumina-tion of films taken with high-speed motion picture cameras

on continuous moving film at the rate of upward of 2,000frames per second, Henry M. Lester, of New York City,reported at the recent meeting of the Society of MotionPicture Engineers. He accompanied his description of themethods employed with motion pictures and demonstra-tions. High-speed cameras are now in use, he said, thatproduce exposures of from 1/10,000 to 1/30,000 second.Such brief exposures call for illumination of great intensityand high color temperature. Incandescent lamps capableof providing such illumination, especially when operatedat voltages higher than their respective rating, have many

disadvantages, he stated. Among them are great power

requirements, heavy conductors and the development ofconsiderable heat. "Operating on the current of a 6-voltdry cell (Hot Shot) battery one or more photoflash lampswill provide ample light of high color temperature ofeasily controlled duration," he continued. "Successiveflashing of any number of photoflash lamps is accom-

plished with a Flash Distributor of a simple design."

STANDARD specifications for leather aprons, leathercape sleeves and leather knee-length leggings have beenapproved by the American Standards Association and are

available to those interested. They are the first three ina series of war standards for protective occupationalclothing for factory and other industrial workers. Thesestandards provide specifications for the different kinds ofleather aprons, cape sleeves and leggings, which the com-

mittee considered necessary to adequately protect bothmen and women working in industrial plants from sparks,molten metal, infra-red and ultraviolet rays, and alsofrom limited impact forces. They cover pattern, design,material and construction.

10

SCIENCE-ADVERTISEMENTS 11

Vl4t~4d4'e ~4 0d

Asia's Lands and PeoplesBy GEORGE B. CRESSEY, Syracuse University. McGraw-Hill Series in Geography. 588 pages,7 x 10. Textbook edition, $4.50

The standard treatise on Asiatic geography-the productof 100,000 miles Of travel in Asia and of two decades ofresearch. The book is a comprehensive, readable analysisof the physical environment and human problems of Asia,especially China, Japan, the entire Soviet Union, and

General MeteorologyBy HoRAcE R. BYERS, University of Chicago.

Although based on the author's well known Synoptic andAeronautical Meteorology, this is virtually a new bookin which the author meets the need for a general textembodying fundamentals as well as the modern develop-

India. It is the first volume to approach the geographyof Asia from an American viewpoint, from the beginningof our interests in the Pacific in the days of the clipperships to our present relations with the countries of Asia.

In press-ready in Mayments in synoptic meteorology. This broad treatmentvitalizes the theoretical material by bringing it into thelight of reality and by lifting the synoptic discussionsfrom the generalizations of pure description.

Mathematical and Physical Principles of EngineeringAnalysis

By WALTER C. JOHNSON, Princeton University. 343 pages, 54 x 84. $3.00Presents the essential physical and mathematical prin- ficial or over-specialized. An attempt has been made tociples and methods of attack that underlie the analysis lead the student into building up a set of quantitative orof many practical engineering problems. The viewpoint semiquantitative physical concepts that will constitute ais practical and utilitarian without being either super- firm foundation for more advanced work.

Chemical Engineering NomographsBy DAuE S. DAvis, Wyandotte Chemicals Corp. Chemical Engineering Series. 315 pages,5-1 x 81. $3.50

A critical selection of about 200 nomographs and line tory material and adequate directions for their use. Thecoordinate charts of proven practical value to chemical collection includes Ernst BerI's "Nomographic Chartsengineers and chemists, suitably indexed, in a form large for Density Corrections and Physical Data on Heavyenough to be read easily and supplemented by corrobora- Chemicals."

Electrical Essentials of RadioBy MORRIS SLURZBERG and WILAM OsTERimED, William L. Dickinson High School, JerseyCity. 529 pages, 5 x 8. Textbook, edition, $3.00

A simple introduction to electrical and radio theory, pro-viding the working knowledge of electrical fundamentalsneeded to handle any type of radio set, test equipment, orelectronic device. The book is based on the experience

of the authors during the past twelve years in teachingelectricity and radio to high school pupils and to menworking in the radio and communication industry.

Send for copies on approval

330 West 42nd Street, New York 18, N. Y.

McGRAW-HILL BOOK COMPANY, INC.

AP1UL 21, 1944

Aldwych House, London, W.C.2.

SCIENCE-ADVERTISEMENTS VOL. 99, No. 2573

Survey Courses

Blakiston Bo

* PLANTS AND MAN - C. J. Hylander and 0. B. StanleyIn this text, the fundamental facts of morphology, physiology and taxonomy are studied and theeconomic and ecological aspects are stressed. It admirably serves the need for a one semestercollege text in botany. 308 Illus. 518 Pages. $3.00

* SURVEY OF PHYSICAL SCIENCEfor College Students -Paul McCorkleThis text is highly favored for use in courses where the avoidance of extended philosophical dis-cussions is of importance. The language is simple and accurate. 273 illustrations are included.Laboratory experiments are given at the end of each chapter. 273 Illus. 471 Pages. $2.75

* ELECTRONIC PHYSICS - L. G. Hector, H. S. Lein andC. E. ScoutenThe fundamentals of electricity and light are presented in this text by means of modern elec-tronic concepts. The electrical nature of the atoms of all elements is constantly used in theexplanations. Carefully graded problems follow each chapter. Color is profusely used in theillustrations. 289 Illus. 355 Pages. $3.75

* OUTLINES OF ECONOMIC ZOOLOGY- A. M. Reese4th EditionIn this book the author stresses the economic importance, both beneficial and harmful, of thevarious groups of animals. The material is well organized for supplementary reading by stu-dents in general biology and zoology. 191 Illus. 359 Pages. $3.25

* THE HARVARD BOOKS ON ASTRONOMYEdited by Harlow Shapley and Bart J. Bok

Harvard College Observatory

GALAXIES ATOMS, STARS and NEBULAEHARLOW SHAPLEY L. GOLDBERG and L. H. ALLER126 Illus. 229 Pages Price 150 Illus. 323 Pages

BETWEEN THE PLANETS $2.50 EARTH, MOON and PLANETSF. L. WHIiPPLEF. G. WATSON WHI 2PLE

106 Illus. 222 Pages Each 140 Illus. 293 Pages

THE MILKY WAY Volume THE STORY OF VARIABLESTARS

BART J. Box and PRISCILLA F. BOx L. CAMPBELL and L. JACCHIA93 Illus. 204 Pages 82 Illus. 226 Pages

THE BLAKISTON COMPANYPhiladelphia 5, Pa.

12

APRIL 21, 1944 SCIENCE-ADVERTISEMENTS 13

- U -~~~~~~~~~~~~~~~~~~~~~~~~.

NEW WILEY BOOKSPHOTOMICROGRAPHYTheory and Practice

By CHARLES P. SHILLABER.

The most comprehensive treatment of the subject in any language. A large part of the content is devoted to theactual procedures to be followed, with explanations of how to obtain the best results on various kinds of subjectmatter. The book covers the adjustments and various techniques relating to the microscope and the illuminatingsystem; the use of sensitive material; and the preparation of the specimen. Ready in May.

Approx. 726 pages; 51 by 8a; Probable price, $7.50

EXERCISES IN SECOND YEAR CHEMISTRYBy WILLIAM H. CHAPIN, Emeritus Professor of Chemistry; WERNER H. BROMUND, Assistant Professorof Chemistry; and LUKE E. STEINER, Professor of Chemistry; all at Oberlin College.

An extensively revised edition, with greater emphasis on methods of calculation applied in the mathematical treat-ment of fundamental theory. In Part I the experiments on the theory of ionization, homogeneous equilibrium, andheterogeneous equilibrium have been thoroughly revised and modernized; Chapter I contains much additionalmaterial of value in the laboratory work both in physical chemistry and in quantitative analysis. Part II likewisehas been subjected to extensive revision, with more detailed discussion of the theoretical background and the pro-cedures involved.

Fourth Edition: 216 pages; 8- by 10j; Paper; $3.00

REVIEW OF PHARMACYBy GEORGE W. FIERO, Associate Professor of Materia Medica, University of Buffalo School of Pharmacy.

For the pharmacist or student who desires a ready reference on the official drugs and preparations. The book isdistinguished for its completeness, brevity and comprehensibility. Briefly, it represents a condensed compend ofthe drugs, chemicals and preparations of the United States Pharmacopoeia (latest edition) and the NationalFormulary (latest edition). Special attention has been given to the form in which all data are presented, in orderto make the book a quick, handy reference of maximum usefulness.

Fifth Edition: 117 pages; 6 by 81; $2.50

A NEW MANUAL FOR THE BIOLOGY LABORATORYBy BERNAL R. WEIMER, Dean of the Faculty and Professor of Biology, Bethany College, West Virginia,and EARL L. CORE, Professor of Botany, West Virginia University.

Carefully selected exercises illustrating the general principles of biology. It is intended to accompany the text-books " General Biology " and " Elements of Biology " by Strausbaugh and Weimer, or any other general textbookin biology. Special care has been used in the selection of specimens for study, and of the large number of ques-tions scattered throughout the manual. The inclusion of numerous demonstrations and optional exercises addsflexibility to the manual and makes it adaptable to a variety of courses. Sheets of prepared drawings, as well assheets for drawing by students, are included at the back of the book. Ready in May.

Approx. 214 pages; 81 by 11; Probable price, $2.00

JOHN WILEY & SONS, INC. 440-4th Ave. New York 16, N. Y.

..C--

14 SCIENCE-ADVERTISEMENTS

The CHRONICA BOTANICA Co.International Plant Science Publishers

. Waltham * Massachusetts .0

recently Published:-

Inorganic Nutrition of Plants, by D. R. HOAGLAND.(Prather Lectures at Harvard University.) A con-cise discussion of recent advances and problems inplant nutrition, chiefly based on the outstandingresearches of the author and his collaborators at theUniv. of California. Oct., buckram, 226 pp., num-erous illustr. and plates ................... $4.00

Plant Viruses and Virus Diseases, by F. C. BAWDEN(Rothamsted). Second entirely revised edition. Nochapter remains the same as in the first edition, morethan half have been completely rewritten. Manynew Illustrations. Roy. oct., buckram, 294 pp., 48illustr .......................... $4.75

An Introduction to Pollen Analysis, by G. ERDTMAN(Viisteras). The first and only comprehensive ref-erence work on the methodology and applications ofpollen analysis. Foreword by RfOGER P. WODEHOUSE.Roy. oct., buckram, 239 pp., 46 plates and illustr.

$5.00

Plants and Vitamins, by W. H. SCHOPFER (Univ. ofBern). Translated from the author's unpublishedms. by N. L. NOECKER. Foreword by W. J. ROBBINS.A critical review of the vitamin problem writtenfrom the view point of plant as well as general phys-iology. Roy. oct., buckram, 300 pp., 23 illustr. $4.75

An Introduction to Historical Plant Geography, bythe late E. V. WULFF (Leningrad). Translatedfrom the second Russian edition by E. BRISSENDEN.Revised by the author. Foreword by E. D. MERRILL.Roy. oct., 223 pp., 35 illustr ............... $4.75

The Carnivorous Plants, by F. E. LLOYD (McGill U.).The first comprehensive treatise on these biologicallyinteresting plants since DARWIN'S InsectivorousPlants of 1875. Roy. oct., buckram, 352 pp., sev-eral hundred illustr . ...................... $6.00

Forest Tree Seed, by HENRY I. BALDWIN (N. Hamp-shire For. Dept.). The first modern book dealingexclusively with tree seed in English. With a poly-glot glossary of tree seed terms. Roy. oct., buck-ram, 240 pp., 28 illustr . ................... $4.75

A Short History of the Plant Sciences, by H. S. REED(U. of California). "A most comprehensive pictureof the history and gradual development of our pres-ent knowledge" (Biol. Abstr.). Roy. oct., buckram,323 pp., 37 illustr ........................ $5.00

The Cytoplasm of the Plant Cell, by A. GUILLIERMOND(Sorbonne), authorized translation from the unpub-lished ms. by LENETTE ROGERS ATKINSON. Fore-word by WILLIAM SEIFRIz. Roy. oct., buckram, 247pp., 156 illustr ........................ $4.75

detailedprospectuses

availableon request

Order directly from us, from any bookseller, or ourauthorized agents: New York City, G. E. STECHERTAND CO.; San Francisco, J. W. STACEY, INC.; Toronto,WM. DAWSON SUBSCRIPTION AGENCY; Mexico, D. F.,LIBRERIA C. CERVANTES; Bogota, LIBRERIA CENTRAL;Rio de Janeiro and Silo Paulo, LIVRARIA KosMos;Santiago de Chile, LIVRARIA ZAMORANO Y CAPERAN;

Buenos Aires, ACME AGENCY.

Inorganic andOrganic Chemicals

Biological Stains

Solutions

Chemical Indicators

Test Papers0

Write for copy of our catalog

The COLEMAN & BELL Co.Manufacturing Chemists: Norwood, 0., U.S.A.

IAIJ and~~~~~~~~~~~~~~a--

ERIC SOBOTKAUsed MicroscopesGuaranteed in perfect condition

No Priorities

17 East 40th Street

NEW YORK 16, N. Y.

THE SCIENCE PRESSPRINTING COMPANY

PRINTERS OF

SCIENTIFIC AND EDUCATIONALJOURNALS, MONOGRAPHS

AND BOOKS

Correspondence Invited

LANCASTER, PENNSYLVANIA

14 SCIENCE-ADVERTISEMENTS VOL.. 99, No. 2573

94SINEADETSMNS1

MUFFLE FURNACEWith built-in Rheostat and attached Pyrometer

Recommended as an adjunct to standard muffle furnaces or for use in laboratorieswhere the number of ashings or ignitions does not justify the purchase of a largerfurnace.

SPECIFICATIONSDimensions-9" wide, 12" deep, 13" high.Muffle Size -" x 33/4" x 33/4".Temperature-1850'F. (1000TC.) intermittent; 1500'F. (8500C.) continuous.Rheostat-"Low, "Medium "High," and "Booster" Buttons. Snap switch

on cord.Door-Counterpoised, providing 41/2" square platform when opened.Pyrometer-21/4" scale, in both Centigrade and Fahrenheit.

No. 8715-For110voltsA. C. or D. C ............................................... ;. .... $42.50

W | lCORPORATION, ROCHESTER, NEW YORKOffices and Warehouses

BUFFALO APPARATUS CORP., Buffalo, N. Y. * WILL CORPORATION, 596 Broadway, New York City

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SCIENCE-ADVERTISEMENTS 15APE 21, 1944

SCIENCE-ADVERTISEMENTS VOL. 99, No. 2573

Bacto-AgarBacto-Agar is a purified Agar prepared from

domestic material. In the manufacture ofBacto-Agar extraneous matter, pigmented portions,and salts are reduced to a minimum, so that thefinished product in the form of fine granules willdissolve rapidly, giving clear solutions.

Bacto-Agar is distributed only for use inbacteriological culture media upon propercertification by the purchaser.

Bacto-AsparagineBacto-Asparagine is a purified amino acid

widely used in synthetic culture media and in thepreparation of tuberculin.

Specify "DIFCO"THE TRADE NAME OF THE PIONEERS

In the Research and Development of Bacto-Pepton. andDehydrated Culture Media.

DIFCO LABORATORIESINCORPORATBDDETROIT, MICHIGAN

BOILER

TROUBLE

Taylor Phosphate Comparator is Effective SafeguardScientific phosphate control helps maintain boiler efficiencyby keeping down scale, corrosion and embrittlement.The Taylor Phosphate Comparator enables you to determine. . . and consequently control, quickly and accurately, thephosphate content of boiler water. Determinations aresimple-move the non-warping plastic slide in front ofsample until color match is obtained, read phosphate con-tent directly from values engraved on slide. Accuracy isassured, for all Taylor liquid color standards carry ANUNLIMITED GUARANTEE AGAINST FADING.

Price of High (or Low) Phosphate Comparator,complete .... ... ...........$....$19.00

BOILER WATER SLIDE COMPARATOR-A com-pletely portable outfit available in 2 models: Model P, for

control of phosphates only, with carrying case$26.00; Model W, for control of both pH andg Phosphates, complete with carrying case $50.00

All Prices are F.O.B. BaltimoreSee Your Dealer or Write Direct for FREEBooklet "Modern pH and Chlorine Control."

16

Klett made * * aGlass Absorption Cells

Fused under high temperature with acid, slkali and other

solvent resisting cement. Optical flat walls. Many stock sizes.

Special requirements made to order.

Sele manufacturer in the Usitad States of fused Electophoresis cells

Makers of complete Electrophoresis Apparatus

-KLETT SCIENTIFIC PRODUCTS

Klet-Suimerson Photoelectric Celorlineters, Colorineters, Nephelonieters, Finorime-

ters, 810 Celerhueters, Electopheresis Apparats, Glasn Standards, Kleett Reagents

Klett Man ufacturin Co.17 peat rth Street, New York, New York

MINERALIGHTULTRAVIOLET LAMPS

ForScience and Industry

Great variety of models. Prices $24.75 upWrite for catalog Prompt DeliveryPHOTOVOLT CORP.

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APRIL 21, 1944 SCIENCE-ADVERTISEMENTS 17

for accurate linear measurements of short rangeGAERTNER

MICROMETER S.LIDEStKE _- fitted with microscope or telescope, permit- hortuontai

depth measurementsa

vertical Micrometermeasurements_ focusng

A most desirable feature of these Instruments Is the diversity of applications possible. In addition to the wellIndicated, displacements on small objects can be measured by mounting them directly on the slide. Two slidescan be mounted to form a small coordinate comparator. Etc., etc.

RANGES: up to 4 inches (100 mm) * READINGS: to .00005 inch (0.001 mm)

THE GAERTNER SCIENTIFIC CORPORATION1204 Wrightwood Avenue Chicago 14, U. S. A.

PLATES AND FILMSfor Spectrum Analysis

T HE Eastman Kodak Company makes a number of platesand films which are suited to the various requirements of

spectrum analysis. One of the most recent of these products isEastman Spectrum Analysis Film, No. 2. It has good speed,moderate contrast, and medium resolving power and granular-ity. Its contrast and wave length characteristics are very uni-form throughout the spectral region A2400A-X4400A.

Particulars concerning this and other films and plates forspectrum analysis will be forwarded promptly upon request.

EASTMAN KODAK COMPANYResearch Laboratories Rochester, N. Y.

APRIL 21, 1944 SCIENCE-ADVERTISEMENTS 17

VoL. 99, No. 2573SCIENCE-ADVERTISEMENTS

HEALTH gets top priorityin Americas fightingforces

Vigorous health is essential for the menwho must attack the enemy and bringvictory to the United Nations. In pastwars, disease has taken a far greater tollof life than bullets.Today well equipped government sci-

entific and medical staffs should receivecredit for the fact that America's armedforces are better fed, better clothed andin better physical condition than any

other army in history.Almost countless are the tasks given

the microscope in these undertakings.Spencer's greatly increased facilities are

breaking all production records in the

race to supply the United Nations withthe instruments they so vitally need.

Spencer LENS COMPANYBUFFALO, NEW YORK

SCIENTIFIC INSTRUMENT DIVISION OF

AMERICAN OPTICAL COMPANY

SCIENCE.-ADVERTISEMENTS18