AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS 9

BREMER-WEATHERFORDTextbook of Histology-6th Edition

Emphasis is given to normal functionalchanges in the cell and to their activities inthe living state. Rewritten by HAROLD L.

WEATHERFORD, PH.D., Harvard University.598 Illus., 302 New; 723 Pages; $7.00

LAMBERTIntroduction and Guide to theStudy of Histology

The objective is to prepare an adequatefoundation for the further study of physiol-ogy and pathology. By A. E. LAMBERT,PH.D., University of Iowa. 185 Illus.; 542Pages; $5.00

STILESHandbook of MicroscopicCharacteristics of Tissues andOrgans-2nd Edition

It gives in outline form the main histologi-cal characteristics of vertebrate tissues andorgans. Excellent for identification studies.BY KARL A. STILES, PH.D., Coe College.Illus.; 204 Pages; $1.50

DAVIESFundamentals ofPhysical Chemistry-2nd Edition

This is a one-semester text introducing stu-dents to the fundamentals of physicalchemistry with applications to medicine,biology and allied fields. By E. C. H.DAvIEs, PH.D., West Virginia University.86 Illus., 447 Pages. $3.50

BLAKISTON

BOOKS.

MARSHALLLaboratory Guide in ElementaryBacteriology

This manual presents 92 experimentsgrouped under Introductory Technique;Physiology of Bacteria; Applied Bacteriol-ogy; Serology and Infection. By M. S.MARSHALL, PH.D., University of California.244 Pages; $1.75

NEAL and RANDChordate Anatomy

This text offers material for a sound mor-

phological course with functional interpre-tations. By H. V. NEAL, PH.D., TuftsCollege and H. W. RAND, PH.D., HarvardUniversity. 378 Illus.; 467 Pages; $3.50

NEAL and RANDComparative Anatomy

In this text the facts of vertebrate anatomyare explained in the light of human anat-omy and tied together through embryology.By H. V. NEAL, PH.D., Tufts College andH. W. RAND, PH.D., Harvard University.540 Illus.; 739 Pages; $4.75

DAVISON-STROMSTENMammalian Anatomy-6th Edition

A standard text on the anatomy of the cat.It will give a sound, practical knowledge of

the essentials of each organ system. By F.

A. STROMSTEN, D.Sc., University of Iowa.174 Illus.; 328 Pages; $3.00

THE BLAKISTON COMPANYPHILADELPHIA

5, PA.

Successful Textsfor

Biology Students

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS 9

SCIENCE-SUPPLEMENT VOL. 102, No. 2642

SCIENCE NEWSScience Service, Washington, D. C.

DDT ROTENONE SPRAYSPRAYING with DDT and rotenone mixture provides a

practical and economical solution of one of the major

problems of cattle raisers in tropical and sub-tropical

regions, control of cattle ticks, it was announced at the

Third Interamerican Agricultural Conference by Dr. Earl

N. Bressman, Director of the Interamerican Institute of

Agricultural Sciences. It is expected that the new

method will be applicable from the northern provinces

of Argentina to the southern United States.Cattle-dipping vats, which have been widely successful

in tick control in temperate regions, have had consider-

ably less success in the tropics, for a variety of reasons.

Over large areas the necessity of depending on relatively

untrained personnel resulted in high mortalities because

of poorly designed dipping vats, arsenic poisoning of

cattle, mechanical abortion and other injuries. Further-

more, the intense tropical heat often caused deaths from

overheating, especially in the case of animals that had to

be driven long distances to the vats-which often cost in

the neighborhood of $4000 each-and the cattle sufferedfrom decreased milk production and, in the case of the

ubiquitous oxen, from lack of rest following dipping.After 110 experiments over a period of three years, Dr.

Robert L. Squibb, of the Division of Animal Industry ofthe institute, developed a new spray solution, specific foruse against the cattle tick, a mixture of DDT and rote-none. One hundred cubic centimeters of the solutionis sufficient, used as a fine spray, to cover an animal, at

a cost of as little as one half cent, depending on localconditions. A wide variety of spraying equipment, rang-

ing from a hand-operated flit gun to power equipment,secures equally effective results. A tick mortality of95 per cent. has been recorded from animals with an

infestation of as high as 40 ticks per square inch.Length of effectiveness of the treatment varies with

climatic conditions, as does cattle dipping, and the solu-tion has continued to give protection against the ticks

up to 80 days. Spraying between the animals' legs and

in body crevices is not necessary since once engorged tickshave dropped off, the animal is not reinfested during the

period of spray effectiveness. More than 7,000 applica-tions have been given over a period of nine months, with

no indication of a poisonous tendency.

ITEMS

A NEW platinum material, for laboratory ware such as

crucibles and other articles now made of platinum alone,has been developed and is a combination of all platinum-family alloys. The new product, developed because of

war necessity and now thoroughly tested in actual use, is

claimed to be superior to the platinum ware it may re-

place. The new material is a product of the Oscap Manu-

facturing Company, and it has been tested over months

in Army, industrial and university chemical laboratories,and found satisfactory in all, it is said. The color of

the new material is the silver gray of regular platinum,

but slightly darker. It is non-oxidizable, has high tensilestrength and flexibility, and is resistant to all acids exceptboiling aqua regia, a mixture of concentrated hydrochloricand nitric acids.

A NEW non-petroleum lubricant for automobiles, air-craft and other internal combustion engines has been de-veloped and tested that is claimed to have unusual advan-tages over mineral oil, particularly in cold weather. Itsproperties are quite different in many respects from oilsderived from petroleum. It is wax-free and can be madeto any desired viscosity. The lubricant is a product ofCarbide and Carbon Chemicals Corporation and is now

being produced in commercial quantities. Its use in

engines has been studied for several years in a largenumber of vehicles. Large quantities are in use in mili-tary equipment, and, at the present time, sale of thematerial is limited to war uses. No petroleum oils are

contained in the new lubricant. It has a density approxi-mating that of water. It is characterized by low changein viscosity with change of temperature. Carbon resi-due values are very low. Sludge and varnish formationin the engine is practically eliminated when the new

lubricant is used, and wear of moving parts is in line

with wear experience with ordinary mineral oils.

A COAL tar fuel widely used in the United Kingdomduring the war years, and still in use, has been described

by the Ministry of Fuel and Power. It is a creosote-

pitch mixture, with about equal parts of the two sub-stances, and is made entirely from English-producedmaterials. The 50-50 creosote-pitch fuel mixture is

homogenous, and the so-called free carbon consists of

microscopic particles of resinous material, which, when

the fuel is held in storage at from 80 to 90 degreesFahrenheit, remain permanently dispersed. Heatingequipment formerly used with other liquid fuels can be

used with this coal tar product, provided certain minor

adjustments are made. If used with petroleum fuels, the

equipment must be thoroughly drained and flushed with

hot creosote oil, because if petroleum fuels are allowed

to mix with tar fuels, the resinous matter in the latter

is immediately precipitated.

AN electrical instrument, so sensitive that it can mea-

sure movements, or changes in position, as small as one-

tenth of a millionth of an inch, has been developed at the

Battelle Memorial Institute, Columbus. It is a tool to

measure the position of either slowly or rapidly movingobjects withoutftouching the object itself. Its first prac-tical application was in measuring the errors in high-precision lathe spindles used in machining aircraft motor

parts. The instrument is also the heart of an apparatusfor measuring and recording the changes in crystal struc-

ture when steel is heated rapidly, as in electric welding.Other possible, but as yet undeveloped, uses of this elec-

trical micrometer are as a meter to indicate the poweroutput of airplane engines in flight, and as a means of

measuring roughness and hardness of metallic surfaces.

10

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS 11

ELECTRON OPTICS AND THE-ELECTRON MICROSCOPEBy V. K. ZWORYKIN, G. A. MORTON, E. G. RAMBERG, J. HILLIER, A. W. VANCE; All at RCALaboratories, Princeton, N. J.

This comprehensive book covers the electron microscope in all its phases. The material waschosen to fulfill a two-fold purpose. The first is to aid the present or prospective electron micros-copist in understanding his instrument and using it to greatest advantage; the second, to pre-sent systematically the practical and theoretical knowledge which must form the basis for furtherprogress in electron microscope design. September 1945.

Approximately 759 pages; 5% by 8%; Probable price $10.00

MANUAL OF CHILD PSYCHOLOGYEdited by LEONARD CARMICHAEL, President; Director of the Laboratory of SensoryPsychology and Physiorogy, Tufts College

A handbook of facts, established theories, techniques and methodology, which surveys the fieldof child psychology and evaluates the results of research in the psychology of human develop-ment. With nineteen separate chapters, each written by a recognized authority, the book is anadvanced scientific manual, giving the most complete bibliographical survey of the literature onchild development now available. It is written for serious students as well as for specialists inpsychology and in such related fields as education, psychiatry, pediatrics, and medicine in general.September 1945.

Approximately 1459 pages; 61/8 by 8 '/16; Probable price $6.00

AERIAL NAVIGATIONBy H. E. BENHAM, Director of Ground Training, Pan-American-Grace Airways, Inc.

This book is designed to provide students of aerial navigation with practical data for use intheir study of a practical science. Simple yet complete, it explains the latest techniques in thefield and includes problems applying theory to actual cases. The book is suitable for use incollege courses or in airlines' pilot training courses. September 1945. .

Approximately 336 pages; 5% by 8%; Probable price $3.50

ORGANIC SYNTHESES. Volume 25W. E. BACHMANN Editor-in-Chief

Tested laboratory methods for preparing various organic chemical reagents in one-half poundto five pound lots. This volume covers the preparations worked out in this past year. September1945.

Approximately 120 pages; 6 by 91/4; Probable price $2.00

PLANE AND SPHERICAL TRIGONOMETRYBy H. A. SIMMONS, Professor of Mathematics, Northwestern University

This greatly enlarged second edition begins with the trigonometric functions of the generalangle, instead of the positive acute angle and includes precisely the solid geometry needed forthe study of spherical trigonometry. The book contains not only theoretical spherical trigo-nometry, but a large number of applications, including introductory navigation and certain ele-mentary problems of astronomy. There are also chapters on Complex Numbers and the SlideRule. August 1945.

Second Edition; With tables; 519 pages; 5% by 8%; $3.00Without tables; 389 pages; 5% by 8%; $2.25

JOHN WILEY & SONS, Inc., 440-4th Aye., New York 16, N. Y.

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS .11

SCIENCE-ADYERTISEMENTS Vot. 102, No. 2642

QUICK' .,i

COlIVENIENT

*De teralautiec' #it*T.AC:CUT..INT.',':'plTEST PAPERSi--

* Accutint .pH :test papes are dsmple, accuaeanld rapid .meas p1 mking .byd rnea ion detem-nations. Merely place a dirop of the soiption orpre a small'nount of e moist solid beingexamined on a strip of the test pap, obsere thecolor ghase which occurs, then gak a comparson with the pr-nted color itandard on the vial.Each stip reacts to produce a distinte Color'reion at each pH hlewiti its orindicates that adjacet range must be used forfurther determiationWide range and fractional range Accutint test

papers are available. The use of wide-range pa-pets is recoimended where iI valutes are notknown to be within the limts of a fractionalranue tper. By using wide range paper for aninitial 4etermination, lH can he am atred within'1.0 pH, and, to obtain grepre , a sec-ond determination is atade with iie correct frac-tional range paper, to within 0.3 pH.

Beca5srracto..,. range : ebrlp e-chother, it is possible to ae 0.2 or 0.1pH. For example, the following p L es canbe determined from the color stanvarious pap covenng the range 5. 8.T1iTh'.0 5.1, 5.2 5.3, 5.4 5.5 5.6 5.9 6.1

6.3, 6.4, 6.6, 6.8, 6.9, 7.0, 7'.1, 7.'2, 7., 7.4, 7.57.8, 7.9, 8.1, 8.2, 8.4,. 8.6, 8.8.

If a' p11 indication is e ierst or s nolo ofa fractional ran paper, a second determination

paper of the next range can be made to.n&-he -original m s-ur t. e p*from a particular fraconal range registers acolor shade betweep A*-ogof its range, the ppq is user goturn to the adjacent frnactiofal tfnge above btbelow where the intermedipte value will be re.vealed by its distinct color standard.

Accutint PH test papers ofer a complete ndaccurate pH rice of hibest Senitivity. It iscomprised of three wide ranges or pH lcalizersof superior accuracy in the high lka ne and highadid ranes as well a in all the middl ranges

1acib daf swppiled"witk a printed color sftndard

Wide. Range Test PaperNo. A c

pH Range 0.0.5.0 1.0.92.0 | .0-4.0

prettomal Reuge Test PaperNo. 10 20 30 40 50

pH Ran 00.L2 24 934.3 1M4.0 L.3No. 60 70 80 90 900

pH Range 2.74.7 3.94.4 5.06.6 5.24.9 5.3-7.0

pH Ransg 6.1-7.4 6.94.4 7.24.8 7.34.8 8.4-9.4No. 160 70 90 200

pH Range 89-0. 9.1J104 0.-1-12A10.7-14, .12.4-14.0These are splented by 20 fractional ranges,permittng do' determations to 0.1 pH. Byusing the complete set, 144 pH values betweenpH 0 and pH 14 are deterble.The wide and fractional ranges are best pre-

sented in correlation by color and by graph by the

.pH value in each of the 23 fractional and widei<nges. OThi chart helps in. the selection of themost suitable ranges or papers for a specificpurpose545277' Acun Test aen. The strips areprepared in pad form, each pad consisting of 204trip Packed in glass vials each containing 5pads or 100 stris.Color chart and instructionsare provided wti each viaL.S7 .65

Per 72 Vials,- f)% DiscountPer 144 Vials, 15% DiscountPer 288 Vials, 20% Discount

565278 Aecutlut Master Color Chart. As de-scelbed above. Designed to aid in the selection ofthe most suitable paper for a secfic purpose.

Each .$3.25

E. H. SARGENT & CO., 155.156 lEsf Superjor S*r ef Chicago 11, 11lmisotMichigon Divison: 1959 East Je9frson, Detroit 7. Michigan

Write for bulletin of prices and discounts.

12

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., A,

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS

How hasSOVIETRUSSIA

accomplishedthe impossible?

THE BASIS OFSOVIET STRENGTHBy GEORGE B. CRESSEY

Chairman, Dept. of Geologyand Geography, Syracuse Univ.

A non-political, readable, eyewitness account ofSoviet power in terms of industries, land, cli-mate, agriculture, pedple, regional character-istics, and its potentialities as one of the great.nations. Here is fundamental data necessaryto any realistic appraisal of Russia and herfuture role. Extensively illustrated with photo-graphs and maps.-

At all bookstores * $3.00WHITTLESEY HOUSE A Divbis of te McGraw-H;il BOOK Co.

COLLEGE PHYSICSRevised

By HENRY A. PERKINS, Sc.D.

* "An excellent textbook and noteworthytreatise."-PROFESSOR HAROLD K. SCHILLING.Pennsylvania State College.

* This hard-working teaching companion, inits revised edition, is a thorough, readable text,written with exceptional clarity, and contain-ing 378 new problems without answers. (Theanswers are available to you on request.) Thewide adoptions of this text during the past yearhave shown its ability to teach a great range ofcollege students under today's high pressureconditions. 802 pages, 6 x 9", College List,$4.50

COLLEGE PHYSICSAbridged Revised

By HENRY A. PERKINS, Sc.D.

* The abridged revised edition maintains thesame high standard of the larger book. Thematerial, however, has been carefully read-justed to a shorter, more elementary course,omitting non-basic material so the full explana-tions of difficult problems could be retained.In this edition you'll find the same ample prob-lems both with and without answers. A pro-fusion of diagrammatic illustrations providefurther learning stimulus. 593 pages, 6x9",Educational List, $4.00

Instructors who wish to examine thesebooks may write for complimentary copies

-ii PRENTICE-HALL, Inca70 Fifth Avenue,

13

A complete line for clinical laboratories de-voted to all branches of chemistry, bacteri-ology, hematology, and parasitology. Testedand checked in our own clinical laboratoriesPurity warranted. Our facilities assure promptshipment of large or small orders. Inquiriesinvited

NEW CATALOGReagents catalogued alphabet. &i|"ically-also according to sub- NOWzjects and techniques, plus med -flEAical reference guide. Catalog READecomprises full line blood test-ing sera including anti-Rh, /cs _anti-M and anti-N; also re-.agents for Wassermann, Kline, | "L*,'and Kahn tests. Write for your /I pe Icopy. FREE ON REQUEST. /,4 Stff

11New York 1 1

T LE MARKET PLACERATES to be paid in advance. Regular setting 10¢ a word, minimum charge $2.00 each; count 8 words if a box address isused. Display, 3 inches maximum, $8.80 per column inch. No discounts or commissions.SEND advertisements with remittance to the ADVERTISING DEPARTMENT, American Association for the Advancementof Science, SMITHSONIAN INSTITUTION BUILDING, WASHINGTON 25, D. C. Correct remittance must accom-pany instructions and copy and advertisements will be published in sequence of completed orders.ADVERTISERS are requested to mention in their announcements the section of the country in which a position is open or de-sired to ensure replies only from employers or prospective employees geographically available.SUBMIT copies, not original documents, when replying to advertisements. Advertising circulars will not be forwarded and tothat end all letters will be opened for inspection at the forwarding office.

PERIODICALS

Wanted to purchase Scientific Periodicals For-eign-Domestic. WALTER J. JOHNSONt, 125East 23rd Street New York 10, New York

For Sale: Medical, Chemical, and Scientific Peri-odicals. Sets, volumes, copies. B. LOGIN ANDSON, INC. Established 1887, 29 East 21st St.,New York 10.

What Are You Interested in? We can supplybooks and periodicals on any subject, new or out-of-print. Send your want list. Periodical Ser-vice, Box 327, Swarthmore, Pennsylvania.

SUPPLIES AND EQUIPMENT

We still have considerable stock of Gruebler Stainsand Kahlbaum Chemicals. Write for quotations.AKATOS, INC., 55 Van Dam St., New York 13, N. Y.

Write for New Oat. No. 67 onAnalytical Filter Papers

Schleicher & Schuell Co.Plant and Lab: South os, Mass.

Head Office: 116-118 West 14th St.New York 11, N. Y.

POSITIONS WANTED

Opportunities Wanted-Biochemist; B.S. in chem-istry; five years' graduate study; Ph.D. (majorin biochemistry; minor, physiology); experience hasconsisted of several years as research chemist in de-partment of pathology of large teaching hospitaland several years in charge of clinical chemistry;for further information, please write BURNEICELARSON, Director, Medical Bureau, Palmolive Build-ing, Chicago 11.

Ph.D., Princeton, seeking academic connection,principal research interest fields of endocrinologyand metabolism, now pleasantly connected withethical pharmaceutical firm. For further informa-tion, please write Patricia Edgerly, Director, NewYork Medical Exchange, 489 Fifth Avenue, N. Y. C.

POSITIONS OPEN

Large Pharmaceutical Firm, East, needs Ph.D. tolearn all phases of products, place research prob-lems in medical schools, supervise research and re-port on clinical findings, $5000-$6000. New YorkMedical Exchange, (Patricia Edgerly, Director),489 Fifth Avenue, New York City.

Position open in the Department of Gross Anatomyof one of the larger Eastern medical schools to befilled by graduate student, instructor or assistantprofessor, title and salary depending on previousexperience and other qualifications. Maximumsalary available $3,500. Number of teachinghours-390 per year. Box 205, "SCIENCE," Smith-sonian Institution Building, Washington 25, D. C.

POSITIONS OPEN

RESEARCH DIRECTORMiddle-west organization with diversifiedline of products and ample resources wantsman with background and experience toorganize and direct research laboratory.Must have basic knowledge in modernphysics, coupled with a general knowledgeof modern industrial processes and ma-terials, and preferably experience in metal-lurgy. Should be able to plan industrialresearch programs and direct their solution.Future only limited by ability.

Box 209 SCIENCE

Smithsonian Institution BuildingWashington 25, D. C.

Opportunities Available-(a) Bacteriologist, phy-sician or Ph.D., to become associated with patholo-gist, Diplomate American Board and director oflaboratories, 200-bed hospital having universityaffiliations; duties consist of supervising staff oftechnicians, research, teaching; $3500-$4000. (b)Medical editor; young physician or one withscientific training in some field allied to medicinerequired; possibility of duties including clinicalresearch; laboratories of pharmaceutical company;East. (c) Instructor or assistant professor of phar-macy; midwestern university. (d)- Hematologistand, also histologist; interesting appointments inresearch institution; beautiful new laboratoriesopened about a year ago, well endowed and splen-didly equipped; central metropolis. (e) Bacteri-ologist qualified to conduct fundamental andapplied research work on bacterial transformationof petroleum hydro-carbons; should be wellgrounded in soil bacteriology or industrial micro-biology, biochemistry and quantitative analysis andable to direct research; research laboratoriespetroleum company; Pacific Coast; $4000-$6000.(f) Psychoanalyst to become associated with groupand hospital specializing in psychiatry and neu-rology; interesting association; Middle West. (g)Bacteriologist well qualified in medical para-sitology; municipal laboratories established toutilize recently developed laboratory diagnosticprocedures in connection with virus diseases;Middle West. (h) Men for clinical posts insurgery, obstetrics-gynecology, pathology, neurologyand psychiatry and pharmacology; universityoperated under American auspices in Asia; countrypredominantly Christian; city in which universityis located has population of 150,000 and is con-sidered important seaport. S8-3 Medical Bureau(BURNEICE LARSON, Director) Palmolive Building,Chicago 11.

1-iN

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AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS 15

STANDARD FOR RESEARCH & DEVELOPMENT

THE CARVERLABORATORY

PRESS

MANY important developments and improve-ments in plastics and other materials have

resulted from experimental work on The CarverLaboratory Press.

Compact in size, yet powerful enough to exert 10tons pressure on 6 in. by 6 in. platens, the CarverLaboratory Press provides for a great number ofapplications. It operates with self-contained hy-draulic unit; fitted with large accurate gauge offinest construction, rigidly mounted on base. Spe-cial gauges are available for low pressure work.

Carver Press accessories include electric and steamhot plates and test cylinders or molds. Additionalinterchangeable equipment for general research in-cludes bearing plates, cage and filtering equipment,etc. The press and certain of the accessories arepatented. Send for catalog which gives full details,applications and prices.

Prompt Deliveries

FRED S. CARVERHYDRAULIC EQUIPMENT

AGAIN AVAILABLEDowmetal Multiple Carriers

forLarge Scale Blood Testing

Cat. No. 380 6-place multiple carrier forsix 5/8" x 4" blood serum tubes.

Cat. No. 381 8-place multiple carrier foreight 1/2" x 4" blood serum tubes.

128 Tube Capacity

Shown above, the 16-place head, No. 250A,for the Size 2 Centrifuge only, completewith sixteen No. 381 carriers. Total ca-pacity 128 ½" x 4" tubes. With No. 380carriers, capacity 96 5/8" x 4" tubes. Samecarriers may be used in the 8-place head,No. 240, in the Size 1 Centrifuges withone-half the number of tubes.

Consult Your Dealer or Write Us

INTERNATIONAL EQUIPMENT CO.352 Western Ave. Boston, Mass.

Makers of Fine Centrifuges

W

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS _5

341 HUDSON ST. NEW YORK

VITAMIN TESTCASEIN

IN VITAMIN EXPERIMENTATION the

type of protein used may well bethe most important dietary factor.When Vitamin Test Casein GBIis the protein of choice in the de-ficiency diet, uniform and consist-ent depletion oftest animals occurswell within the required time in-terval specified by the U.S.P. orother standard test methods.Vitamin Test CaseinGBI is pre-

pared by a special hot alcohol ex-traction method, which removesnot odly the fat soluble but thewater soluble vitamins as well. Itis therefore free of vitamins A andD as well as the known factors ofthe B complex and vitamin K.

Vitamin Test Casein GBI issupplied in: 1 lb. bottles, 5 lb.,25 lb., and 100 lb. fiber drums.

PROMPT DELIVERY

GENERAL BIOCHEMICALS, INC.DIVISION WYETH INCORPORATED

LABORATORY PARK, CHAGRIN FALLS, OHIO

1ntf

AUGUST 17, 1945 SCIENCE-ADVERTISEMENTS 17

Eastman High Resolution PlateTHIS PLATE is specially made for preparing graticules, and for

other purposes requiring the resolution of a fine structure ofsharp, dense lines. Its resolving power is over 500 lines permillimeter.The plate is also known as the Eastman Spectroscopic Pt*,,

Type 548. It is normally supplied as Type- 548-GH, havgorthochromatic sensitizing with a maximum sensitivity aabout X5640A., and with antihalation backing. Other sernatizeings may be obtained on special order.

Further information will be forwarded upon request.

EASTMAN KODAK COMPANYResearch Laboratories Rochester 4% N.YX.

LaROSA SULFA TESKITTest Paper Method of Dr. Wm. V. Lalosa-J.Lab. & Clin. Med., June, 1945.

For estimating the concentration of Sulfa drugs(free form) in blood and body fluids.

The set, measuring 4" x 3?" x li", includes capillarytubes, and test papers for 100 tests. The readingsare made through the use of a special color chartand porcelain strip. This simple and reliablemethod operates as follows:

1. Blood is collected in capillary tube and centrifuged.2. Plasmna Is transferred to test paper.3. Test paper placed on porcelain strip and color

compared with chart. Readings in mg. per 100 cc.

Price complete as described$5.00 plus postage

LaMotte Chemical Products Co.Dept. "H"' Towson 4, Baltimore, Maryland

Deluxe Met-aTRIPOAhSCREEN;[I>Model DS-The eas-iest operating screen onthe market today; hasno s et screws, springplungers, o eI -er hand.operated locking, devicesto work loose. Positivelocking in any position;assures perfect screensuspension. Availahiein Radiant- "Hy-Flect"Glass B ea d ed Screensurface that- shows re-markable increase, inbrilliance a n d clarity

Model "D8" for all types of projec-tion.

Write for Free Bulletin-

JARRELL-ASH COMPANYManufacturers-Importers--Dealers

165 Newbury Street Boston. 16, Man.

---4

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18 SCIENCE-ADVERTISEMENTS VOL. 102, No. 2642

Precision Brings Pacific VictoriesAimed with deadly precision, aerial

torpedoes have been a decisive factor inPacific victories.

Early in the war, U. S. Navy TorpedoSquadrons launched their "tin fish" bydiving in dangerously close to theirtarget. The risks were great-but theysank plenty of Jap ships.The problem in this type of attack

is to estimate the distance to the targetand the speed of the target. He must aim-not where the ship is, but where itwill be when the torpedo strikes.To solve this problem, he uses a Tor-

pedo Director in which an enemy ship

can be centered easily and quickly.The Torpedo Director is one of many

Spencer scientific optical instrumentsthat speed Allied victory.

American 1 OpticalCOMPANY

Scientific Instrument DivisionBuffalo 11, NewYork

/Z~uc161e6f/~ Cq< SPENCER fU1/

is SCIENCE-ADVERTISEMENTS VOL. 102. No. 2642