For work in theExtreme Ultraviolet...

Welength 500Wave legh(A)

From now on, the difficulties that arise in somephotographic work from the absorption of gelatincan be expected to diminish.For now you can get from Kodak an emulsion

containing considerably less gelatin than usual. It isbeing offered on an experimental basis as KodakSWR Film, available only in 35mm. width,unperforated, in 25-foot rolls. (It is recommendedonly for uses where abrasion sensitivity and emulsionfragility are not objectionable.)Kodak SWR Film offers particular advantages for

spectrography in the extreme ultraviolet over thetechnic of treating a conventional emulsion with afluorescent substance that converts the radiation

2000 to light of longer wave length. Here's why:* Kodak SWR Film gives nearly five times as much

speed in the vicinity of 550A as the older technic.* Grain size is less.* It has very low background. (Maximum backgrouad

density is about 0.1.)

The curves at the left are typical of the newmaterial (but are not to be regarded as fixedquantitative specifications).

If you'd like to see what you can do with KodakSWR Film, just drop us a note. We'll be glad towrite you where to buy a roll.EASTMAN KODAK COMPANYRochester 4, N. Y.

"Kodak" is a trade-mark.

I -9

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VC 1.20

IDj 1.0

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AVERAGE GRADIENT vs. WAVE LENGTH

KODAK SWR FILM (EXPERIMENTAL

KODAK SPECTROSCOPIC PLATE,Type 103-0, U. V. Sensitive

'0 1000

A

A11

SCIENCE August 5, 1949, Vol. 110

Water Solble Indicatorsfor pH DeterminationsThe indicators listed below are now available as

the sodium salts and are designated W.S. (watersoluble). The older technique of using these indi-cators involved the use of insoluble indicators (freeacid compounds) and effecting solution by the ad-dition of definite amounts of standard sodium hy-droxide solution. The use of the water solubleindicator eliminates the difficulties encountered inthe older procedure. The label upon the packagecarries information regarding the amount of theindicator to be used to prepare a solution orre-sponding to a 0.04% or 0.02% solution of therespective acid indicator.

NEW LOW PRICESNAME pH Range 1 gm. 10 gn.

Thymol Blue, W.S....... .1.2-2.8 $1.20 $10.00(Thymol sulfon phthalein, ( 8.0-9.6Sodium salt)Brom Phenol Blue, W.S.............3.0-4.6 1.20 10.00

(Tetra bromo phenol sulfonphthalein, sodium salt)Brom Cresol Green, W.S.............4.0-5.6 2.40 20.00

(Tetra bromo-m-cresol sulfonphthalein, sodium salt)

MethylRed, W.S .....................4.4-6.0 .61

(Di methyl amino azo benzene-o-carboxylic acid, sodium salt)Brom Cresol Purple, W.S..........5.2-6.8 1.20 10.00(Di bromo ortho cresol sulfonphthalein, sodium salt)Chlor Phenol Red, W.S................5.0-6.0 2.40 20.00(Di chloro phenol sulfonphthalein, sodium salt)Brom Thymol Blue, W.S.............6.0-7.6 1.20 10.00

(Di bromo thymol sulfonphthalein, sodium salt)Phenol Red, W.S 6.8-8.4 1.20 10.00

(Phenol sulfon phthalein,sodium salt)Cresol Red, W.S 0.2-1.8 1.20 10.00(Ortho cresol sulfon a;2-8.8phthalein, sodium salt)Meta Cresol Purple, W.S . ..j 126-9.8 2.40 20-00(Meta cresol sulfon 7.6-phthalein, sodium salt)

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

GCLASS ABSORPTION}CELLS made KLETT

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ELECTRO-MEDICAL LABORATORY, INC.HOLLISTON, MASSACHUSETTS, U.S.A.

Pioneer manufacturers of the electroencephalograph

10 SCIENCE August 5, 1949, Vol. 110

a

August 5, 1949, Vol. 110 11

Recent and forthcoming extbook8

Laboratory Explorationsin General Zoology

Revised EditionBy Karl A. Stiles

This revision of a popular manual follows the same general plan of the first edition,with some changes in the order of the material and several new additions. Thebook has been revised throughout, now offering a wider range of material butretaining the flexibility of the first edition. Published June 28. $3.25

General Chemistry-A Systematic ApproachBy Sisler, VanderWerf and Davidson

A text for general chemistry courses, this new book emphasizes the modern princi-ples of atomic structure and the nature. of the chemical bond. An abundance ofdescriptive, factual material is provided, organized in terms of the theoreticalprinciples involved. Designed for use in all but the most elementary freshmanchemistry courses, it is particularly well adapted for chemistry majors, engineers,pre-medical, pre-pharmacal. and other technical students. To be published inSeptekmber. $5.00 (probable)

College BotanyBy Hylander and Stanley

This new text is designed for a full-year course in general botany. Part I dis-cusses the individual plant and its life problems, using a woody green plant tointroduce the student to the basic facts of plant morphology, histology, and-cIstructure and function; Part II deals with plants as groups in our large vegeta-tion complex. To be published in 4ugust. $6.00 (probable)

The Supersensitivity of Denervated StructuresExperimental Biology Monographs By Cannon and RosenbluethThis monograph is an examination of the data which lead to the inference thatdirectly or remotely denervated structures become sensitive to the excitatory aswell as to the inhibitory actions of sundry chemical substances and of impingingnerve impulses. Many physiological and clinical implications of the law are dis-cussed. Published June 28. $5.50

THE MACMILLAN COMPANY, 60 Fifth Avenue, New York 11

August 5, 1949, Vol. 110 SCIENCE 11

SCIENCE August 5, 1949, Vol. 110

LIMNOLOGICAL ASPECTS OFWATER SuPPLY AND WASTE DISPOSAL

i v+ 87 pages-6 x 9-illustrated-clothbound- 7949

,'4. This volume of 20 papers treats of a field of science of rapidlyincreasing importance. In it engineering and limnology meet,and government plays an important role.

The papers in this new volume are not simply academic discussions of possibilities,but of sound biological and engineering science as applied to current practice innorthern Wisconsin and Minnesota. The 12 contributors to this volume are largelyfrom that area, but several are connected with institutions from Ohio to Boston.

PRICES FOR THIS BOOK IN CAR.TONS, postage prepaid, are as follows:

Members of the A.A.A.S. ..... $2.75

Nonmembers and Institutions 3.25

Please enclose remittance with order

ORDER YOUR COPY NOW!

To: AAAS PUBLICATIONS1515 Massachusetts Ave., N.W., Washington 5, D. C.

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TRYPSINPure Crystalline, 15% total ni-trogen. Watersoluble. Guaran-teed Potency 1: 10,000. Ca-sein substrate. Prepared bymethod Kunitz and Northrup,J. Gen. Physiol. 19, 991 (1936)

PANCREATINPotency 1:100 Casein substrate.

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12 SCIENCE August 5, 1949, Vol. 110

August 5,1949,VoL 110 SCIENCE 13~~~~~~~~~~~~~~~~~~~~~~

"Jagabi" Rheostats insure precise current control over along service life by combining ruggedness of constructionwith instrument accuracy. Small to large, each rheostat per-mits the nicety of adjustment necessary for precision controlof associated equipment. Positive action and smooth operationare attained through the "Lubri-tact" feature-a unique per-manently lubricated sliding contact. A full range of "Jagabi"Rheostats in 4 sizes, with 76 different ratings, and a varietyof type are carried in stock. Write for Bulletin 1745-SM.

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P HOTOVO ITElectronic Photometer

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August 5, 1949, Vol. 1 10 SCIENCE 13

August 5, 1949, Vol. 110

Personnel Placement

POSITIONS WANTED

Bacteriologist, Applied; M.S.; 22; capable and industrious; someexperience. Interested Industry, Academic Research, Universityteaching. Box 289, SCIENCE. X

Biologist; Ph.D.; past seven years, head, department, biology,small college; prefers combination teaching research; particularlyinterested endocrinology, physiology; capable of executive work in-volving development biology department on graduate or under-graduate levels; experienced in newspaper science writing-; forfurther information please write Burneice Larson, Medical Bureau,Palmolive Building, Chicago. X

Botanist: M.S. One year's experience instructing GeneralBotany labs. Desire to teach Ecology, Taxonomy, and GeneralBotany. Box 286, SCIENCE. X

Cytologist, Ph.D., Histology, Hematology; 3 years Cancer work.Interested research or teaching. Box 285, SCIENCE. X

Mathematician: M.A.; Completing Doctoral dissertation, desiresteaching or research position. Box 290, SCIENCE. 8/12

POSITIONS OPEN

Biochemist: Ph.D., capable of independent work. Wanted bypharmaceutical firm. Good background in basic medical sciencesrequired. Experience in enzymology desirable. Submit completepersonal and professional data. Box 281, SCIENCE. 8/12

Endocrinologist: (Ph.D.), wanted by eastern drug firm for researchin the biochemistry and physiology of hormones. Must have broadbackground of experience and interests. Give complete personal,educational and experienice resume. Box 280, SCIENCE. 8/12

Lecturer in Zoology. The University of Alberta invites applica-tions for the position of lecturer in Zoology, duties -to commenceSeptember 1, 1949. Initial salary-$2800-$3400, according toqualifications and experience. Preference will be given to candi-dates with knowledge of comparative anatomy and/or embryology.Applications, giving complete particulars, should be sent to theDean of Arts and Science, University of Alberta, Edmonton.Canada, immediately. X

Positions Open:(a) Research assistant; M.D. or Ph.D., capable of independentresearch work; problem involves measurement of pressures de-veloped within digestive tract; good background in physicsdesirable. (b) Ph.D. in biochemistry, physiology or zoology; ex-perience in hormone assays and general methods of animal experi-mentation in endocrinology required; pharmaceutical company;East. (c) Ph.D. in biochemistry or pharmacology; duties consistof developmental work in toxicology and radiation effects onliving matter; well known research institution; West. (d) Bio-chemist to head division, laboratories undergoing reorganization;fairly large hospital; Pacific Coast; $6000. (e) Neuroanatomist;Ph.l. or M.D., Middle Western University. (f) Instructor orassociate professor in bacteriology; duties: teaching medical andgraduate students; opportunity for research; university medicalschool. S8-1 Burneice Larson, Medical Bureau, Palmolive Build-ing, Chicago. X

Personnel PlacementPOSITIONS OPEN

Microbiologist: Ph.D., training in chemistry desirable. For re-sponsible position involving microbiological problems related totextile mill operations and participation in graduate teaching pro-gram. Box 284, SCIENCE. X

Physiologist (Assistant Professor) for large Eastern MedicalSchool. 12 weeks teaching; remaining time for research. Ph.D.or M.D. Box 288, SCIENCE. R8/19

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SCIENCE

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SCIENCE August 5, 1P49, Vol. 110~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Market PlaceSUPPLIES AND EQUIPMENT

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SCIENCE August 5, 1549, Vol. 1 1016

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