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CADMIUM STANDARD CELLS

For use with potentiometers, electrometers, and ballistic galveno. meters, or wherever else a precision standard of electromotive force to needed.

Negligible Temperature Coefficient.

Highly Constant E. M. F.
Contents hermetically sealed in glass so that lowering of electro-
motive force due to evaporation is impossible.

Mounted in moulded box, or unmounted.
My comparison certificate accompanies each cell without charge.
Bureau of Standards certificate extra.

On November 13, 1916, three normal cadmium cells made by me were certified by the Bureau of Standards as differing from their group of reference cells by less than one part in one hundred thousand, all three having the same value.

On March 30 1920, after the lapse of three years and four months, the same three cells were again compared by the Bureau of Standards. The maximum difference among the three was less than one part per hundred thousand, and the maximum difference from their sertified value of 1916, was less than one part per hundred thousand.

In other words, these cells showed a degree of constancy to all intents equal to that considered most highly satisfactory, if not remark. able, in the very best type of precision resistance standards. (see Bul. Bur. of Stand. Vol. 5. No. 3. D. 427.)

The cells in question were in nowise special. They were made of the materials regularly prepared by me, and were set up with

no greater care than that constantly employed in the making of my standards.

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Marion Eppley,

(A.M., Ph.D.)
Physico-Chemical Apparatus.

NEWPORT, R. I.

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No Laboratory Equipment is complete without some variable resistances. To maintain the high standard of your outfit we suggest the addition of some

“Becbro” Sliding Contact Rheostats

(Tubular and Stone Types)

Thousands of these rheostats have been manufactured and sold by us (the original American Manufacturers) to most all Universities, Colleges, Technical Schools and Industrial Concerns and have always given entire satisfaction.

Write for Bulletin C-5

BECK BROS. 3640-42 North Second Street

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Philadelphia, Pa.

H-ION DETERMINATIONS SIMPLIFIED

The new Acree Apparatus with Pyrovolter Potentiometer is a unit outfit (not assembled), offering greater convenience and higher accuracy than any heretofore available. Even from a cost standpoint, it is worthy of your close investigation,

Ask us for our New Price List of Apparatus for Pa

Measurements, requesting CS-18

Pyrolectric Instrument Co.

636-640 East State Street

TRENTON, N. J.

Grahame Chemical Company

100 Rockingham Street
ROCHESTER, N. Y.

Eastman Organic Chemicals

OUR new price list now ready contains over 900 items. Among

those not yet announced are the following:

938 * Acetyl p-Aminobenzoic Acid 941 * Acetyl n-Propylaniline 366 * p-Chlorophenol P942 dl-Malic Acid 946 * Methyl Cyclohexane

936 * Beta-Naphthol Iso-Amyl Ether
947 * Orcinol
944 * Propyl Red (Indicator)
939 Urethane
940

Xanthone

*

Of the above list all those distinguished by an asterisk have been prepared or purified in our laboratory.

EASTMAN KODAK COMPANY
Research LABORATORY

Rochester, N. Y.

Natural History Material

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ZOOLOGY MINERALOGY

We have been handling Natural History Material of all kinds for the past fifty years, and so have accumulated a very complete stock. Our prices are as low as the quality of the specimens will permit. We are constantly preparing, circulars and price lists covering our material in the different branches, which we will be pleased to send free of charge to the readers of Science. Some of our recent circulars :

S-121 Rare Bird Skins
S-122 Mounted Bird Skins
S-98 Material for Dissection
S-123 Philippine Land Shells
S-120 Special Minerals
S-110 Complete Trilobites
S-111 Jurassic Fossils

S-119 Cretaceous Fossils CONCHOLOGY GEOLOGY

"A Boat Passing a Lock"—by John Constable (1776-1837). Constable, like many other great masters, was a consistent user of Whatman Drawing Papers.

Ward's Natural Science

Establishment College Ave. Rochester, N. Y.

Heir to 150 Years of Paper-Making Mastery

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I. Collecting Utensils.
II. Breeding Apparatus and Cages for Living

Animals.
III. Preparing and Preserving Utensils.
IV. Cabinets and Insect Cases.

V. Magnifiers, Microscopes and Accessories.
VI. Botanists' Supplies.
VII. Explorers' and Collectors' Camp Outfits.
VIU. Miscellaneous Naturalists' Supplies.
IX. Oologists' Supplies.

X. Aquaria.
XI. Books and Publications.
XII. Chemicals

K-S Museum Cabinets of Glass and Metal
New Illustrated Biological Catalogue will be sent free

of charge upon application

Chemists who are unaquainted with their present excellence will find it to their advantage to make comparative tests.

Samples gladly supplied on request. Also helpful booklet giving typical applications of the various grades.

THE KNY-SCHEERER CORPORATION

H. REEVE ANGEL & CO.

INCORPORATED 7-11 Spruce Street New York, N. Y.

Dept. of Natural Science

G. Lagai, Ph.D.

404-410 W. 27th St

New York City

Sole Mill Representatives for the United States,

Canada and Mexico

NEW SERIES
Vol. LIII, No. 1367

FRIDAY, MARCH 11, 192.

SINGLE COPIES, 15 CTS.
ANNUAL SUBSCRIPTION, $6.00

FRENCH-ENGLISI MEDICAL DICTIONARY

Prof. John C. Branner,

Stanford University, Calll.

A dictionary of modern French medical and scientific terms has long been needed. Dr. Alfred Gordon, A.B., M.D. (Paris), has prepared one that will meet the requirements of all who have sought for such a work. The author is a physician thoroughly acquainted with the languages represented.

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It is not safe to depend upon the general dictionary for definitions of medical words. In the first place they contain so few such words that one seldom finds the term required, then, the real scientific significance is not pointed out. "Cloison," for example, is a "dividing wall" or "partition" in the general sense, but it is also the anatomical name for "septum" ; "depot," ordinarily means “depository," but it has a chemical significance of

precipitate" and a medical significance of "abscess."

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Words that are spelled alike in both languages should be studied because they tempt one to guess meanings that are quite wrong in most cases; rage " meaning meaning "rabies" ; "chair

rabies" ; "chair" meaning "flesh" ; "pain" meaning "bread ", are examples. The field of French medical literature is one that well repays study. Many who have been brought into contact with it during the war will continue to draw therefrom points of practical value. The French have a marvelous power of observation, and they record facts with great accuracy and precision. To derive full benefit, it is necessary to have for reference a book which gives the exact scientific definition. Dr. Gordon's dictionary gives the pronunciation of each word in English phonetics. It is ideal for the reference library, for the physician, scientist or student. Price, Cloth, $3.50 Postpaid.

PUBLISHERS

P. BLAKISTON'S SON & CO., PHILADELPHIA

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