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se | l^l *e ^eX * >FELL_[Er_ wr}} §ol^S 'Gr~ ~EQW - - - - - * EZ Z
to show longer
nuclear particle pathsThe thicker a nuclear track emulsion, the betterthe chance of catching the start and finish of an
interesting nuclear event. But a very thicklycoated plate is not easy to process evenly. That'swhy all the Kodak Nuclear Track emulsions are
available in unsupported form as pelliclesapproximately 250 microns thick.The newest of the Kodak Nuclear Track
emulsions is Experimental Type NTC3, available
both as pellicles and on plates. Less sensitivethan Type NTA, it is recommended for cyclotronand synchrotron applications where the high
intensity of background radiation poses a serious
problem. Low halide-to-gelatin ratio in Experi-mental Type NTC3 emulsion facilitates grain
counting for protons below 10 MEV and alphaparticles below 100 MEV.For up-to-date quantitative information on all
Kodak Nuclear Track Plates and Pellicles, writeEastman Kodak Company, Industrial Photo-graphic Division, Rochester 4, N. Y.
NUCLEAR PARTICLE RECORDING00 . another function of photography
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For complete information write for 3utletlh
SCIENCE, Vol. 112
KLETTELECTROPHORESIS
CUSTOM MADE
TOOL FOR THE ANALYSISOF COMPLEX COLLOID SYSTEMS, AND FORTHE CONTROL OF PRODUCTION OFPURIFIED PROTEINS, ENZYMES, HORMONES
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Media forTissue and Virus Culture* Serum Ultrafiltrate-Simms* Balanced Salt Solutions* Serums-Ox, Horse, Pooled Human,
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Catalogue & Prices on RequestCatalogue 14S
MICROBIOLOGICAL ASSOUATES, INC.Coral Gables, Florida
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* PHYSICAL CHEMISTRY OF HIGH POLYMERIC SYSTEMSSecond completely revised and augmentededition. By H. MARK, Brooklyn, N. Y.,and A. V. TOBOLSKY, Princeton, N. 1.(High Polymers, Volume II.) 1950. 6x9.520 pages, 155 illus., 107 tables. $6.50
CONTENTS: 1. Geometry of Molecules as Revealed by Diffraction Meth-ods. 2. Behavior of Molecules in Electric and Magnetic Fields. 3.Molecular Spectra. 4. Primary and Secondary Valences. 5. CrystalStructure and Crystal Forces. 6. Crystal Structure and Symmetry. 7.Liquids, Mesophases and the Amorphous-Crystalline Character of Poly-mers. 8. Thermodynamics of Solutions. 9. Kinematics of Liquids andSolutions: Viscosity, Diffusion, and Ultracentrifugation. 10. MechanicalBehavior of High Polymers. 11. Step Reaction Polymerization. 12. ChainReaction Polymerization. 13. Degradation of High Polymers.
* STRUCTURE OF MOLECULES AND THE CHEMICAL BONDBy Y. K. SYRKIN and M. E. DYATKINATranslated and revised by M. A. Partridgeand D. 0. Jordan. 1950. 6 x 9*. 519pages, 87 illus., 174 tables. $8.75
CONTENTS: 1. The Hydrogen Atom. 2. Periodic Classification of theElements. 3. The Homopolar (Covalent) Bond. 4. Saturation and Di-rection of Valency Bonds. 5. Resonance of Valency Structures. 6Resonance of Covalent and Ionic States. 7. Methods of MolecularOrbitals. 8. Spectra of Diatomic Molecules. 9. Vibrational Frequenciesand Interatomic Distances in Polyatomic Molecules. 10. Dipole Moments.11. Bond Energies. 12. Intermolecular Attraction. 13. The ChemicalBond in Crystals. 14. Complex Compounds. 15. The Structure of theBoron Hydrides. 16. The Solution of the Three Electron Problem UsingSlater's Method. 17. The Polyelectron Problem and Resonance Energy.18. Mathematical Appendix. Formula and Radical Index.
ADVANCES IN COLLOID SCIENCE - Volume IIIEdited by H. MARK, Brooklyn, N. Y. andE. J. W. VERWEY, Eindhoven, Holland1950. 6 x 9. 396 pages, 180 illus., 36 tables.$7.50
CONTENTS: 1. J. H. de Boer: Atomic Forces and Adsorption. 2. A. E.Alexander: Surface Chemistry and Colloids. 3. J. Th. G. Overbe'ek:Quantitative Interpretation of the Electrophoretic Velocity of Colloids. 4.E. A. Hauser and D. S. le Beau: Lyogels. 5. Per-Olof Kinell and BengtG. Ranby: Ultracentrifugal Sedimentation of Polymolecular Substances.6. J. H. Dillon: Fatigue Phenomena in High Polymers. 7. StrathknorsR. B. Cooke: Flotation.
MELTING AND SOLIDIFICATION OF FATSBy ALTON E. BAILEY, Louisville, Ky.1950. 6 x 9. 371 pages, 150 illus., 66 tables.$7.00
CONTENTS: 1. General and Theoretical Considerations. 2. LaboratoryTechniques. 3. Melting and Solidification of Pure Compounds. 4. Melt-ing and Solidification of Mixtures. 5. Solubility. 6. Practical Meltingand Solidification Processes.
ADVANCES IN ENZYMOLOGY and Related Subjects of BiochemistryEdited by F. F. NORDVolume 101950. 6 x 9. 543 pages, 29 illus., 27 tables.$7.50
CONTENTS: 1. Tage Astrup: Blood Clotting and Related Processes. 2.Frank C. Happold: Tryptophanase-Tryptophan Reaction. 3. Jean Roc/eand Nguyen-van Thoai: Phosphatase Alcaline. 4. W. Z. Hassid andM. Doudoroff: Synthesis of Disaccharides with Bacterial Enzymes. 5.Norman C. Brink and Karl Folkers: Some Aspects of Streptomycin andOther Streptomyces Antibiotics. 6. C. Martius and F. Lynen: Problemedes Citronensiurecyklus. 7. Theodor Bersin: Die Photochemie desSchwefels. 8. Walter G. Frankenburg: Chemical Changes in the HarvestedTobacco Leaf. Part II: Chemical and Enzymatic Conversions duringFermentation and Aging. 9. Claude E. ZoBell: Assimilation of Hydro-carbons by Microorganisms.
All books available on approval.
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mimeographed 63 + VI pagesOrders for 1 to 4 copies: $1.00 per copy
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Please send me copies: Report of theSpecial Committee on the Civil Liberties ofScientists. My check (or postal note) for
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For the Determination of IronA new sensitive, stable, and widely applicable reagent, de-veloped by John H. Yoe and A. Letcher Jones, Universityof Virginia (Reference Industrial and Engineering Chem-istry, Analytical Edition, Vol. 16, p. 111-115, 1944), forthe colorimetric determination of ferric irbn. The reagentmay be used in either acid or alkaline mecium. In alkalinemedium it is sensitive to one part of irt"z in 100,000,000parts of solution. In acid solution the sensitivity is onepart in 30.000.000.
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SCIENCE, Vol. 112
FOREIGN PERIODICALScovering the war years
243 Titlesmostly German,
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Write for our
Final Periodical Catalog
J. W. EDWARDSAnn Arbor Michigan
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THECARVERLABORATORYPRESSfor Pressing OutSaps, Jukes,Oils, etc.......
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PHOTO VOLTElectronic PhotometerMod. 512 with Photo-Multiplier
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Anatomist: Professor and head, department of anatomy, univer-sity medical school, past 12 years; available immediately; for fur-ther information, please write Burneice Larson, Medical Bureau,Palmolive Building, Chicago. X
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Insect Physiologist: Ph.D., 28; Ecology, toxicology, morphology.Zoology, biochemistry minors. Teaching, research experiencemicrotechniques. Prefer research position, consider teaching.Veteran. Sigma Xi. Available immediately. Box 229, SCIENCE.
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Microbiologist: B.S., M.S., Industrial experience, antibiotics,vitamins, research-development, fermentations, pilot plant, control,assay supervision, mutation induction. Box 230, SCIENCE. X
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Positions Open:(a) Biochemist; Ph.D., clinical laboratory, fairly large voluntaryhospital; newly created position; opportunity research, medicalschool affiliation; $5000-$7000; West. (b) Technically trainedyoung man to take over control and responsibilities of makingintravenous solutions, sterilizing and testing them for sterility andabsence of pyrogens; must be qualified to set up complete standardslaboratory- manufacturing company; East. (c) Young physicianqualified biochemistry to become associated with pathologist,Diplomate and FACP, director of laboratories, large general hos-pital; new laboratory department now being completed; metro-politan area of East. (d) Assistant professor of anatomy to directcourse in embryology, assist in histology and neural anatomy; willconsider Ph.D. in zoological fields if experienced in teaching his-tology and embryology. (e) Chairman of department of pharma-cology, Ph.D.; assistant in physiology, minimum of M.S. degree,trained in neurophysiology and assistant in anatomy; Middle West-ern college. (f) Director of Research, small company, interestingprogram of expansion; physician with research experience, pharma-ceutical industry required; $12,000-$15,000. S7-2 Burneice Larson,Medical Bureau, Palmolive Building, Chicago. X
Personnel -PlacementPOSITIONS OPEN
UNIVERSITY OF DACCA, East Bengal, Pakitan.0 Applications are invited for the following posts
on terms stated against each:1. Professor of Physics-Salary will depend upon
qual ifications and may amount to Rs. 2000/-p.m. including allowances. In exceptionalcases it may be increased to Rs. 2500/-p.m.
2. Professor of Botany-Salary will depend uponqualifications and may amount to Rs. 1500/-p.m. including allowances.
N. B. Re. 1 /-25 1 3¾d i.e. £1 = Rs. 9.24)Appointments will be on deputation or con-
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Applicants should be distinguished scholars, withexperience of University teaching and guiding re-search. Knowledge of English is essential. Candi-dates should give full details of age, nationality,academic career, teaching experience, and originalpublications enclosing a copy of each; also testi-monials and names and addresses of three referees.
Applications must reach the Registrar, Universityof Dacca (P.O. Ramna), East Bengal, Pakistan notlater than 31st August, 1950.
P.S. Special attention is invited to the presentrate of exchange and the extended date for re-ceiving applications.
The Market Place
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Your sets and files of scientific journalsare needed by our library and institutional customers. Please sendus lists and description of periodical files you are willing to sellat high market prices. J. S. CANNER AND COMPANY, 909Boyston Street, Boston 15, Massachusetts. tf
mi n_ YOUR PERIODICALSWe need Complete Sets, Runs, Volumes sad Single numbs.CASH IN on your periodical accumultions NOW!
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July 14, 1950
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ANIMAL CAGES AND ACCESSORYEQUIPMENT
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1* 1 (9_.11
6 x 9 inches, illus-trated, clothbound,277 pages
This AAAS sym-posium volume pre-sents in 24 papersa comprehensiveview of Brucellosis.
The National In-stitutes of Health,the U. S. Depart-ment of Agricul-ture, and the Na-tional ResearchCouncil who co-sponsored the ver-bal presentation ofthese treatises, suc-ceeded in obtainingas contributors pio-neers in this com -
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Cash price to AAAS members $3.50Nonmembers and institutions $4.00
Note: Memprepaid ord
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entennial
71 x 10 inches, double column,clothbound, 320 pages
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abers may use the special prices only for'ers and for one copy of each publication.
LAS, 1515 Massachusetts Avenue, N.W., Washington 5, D. C.Enclosed find my check or money order in the amount of $.........for copies of Brucellosis, copies of Centennial-
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SCIENCE, Vol. 112.
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