iicon

This new single-deck model is asdramatic in improved efficiency asit is radically different in appear-ance from earlier Autotechnicons.

Boon to the busy laboratory . . .

processing or staining at will with-out annoyance of shifting beakers.

excellence in automatic tissue processing

Write today for Booklet 2-A, for descriptionof these new instruments.

THE TECHNICON COMPANYChauncey * New York

Smk- I --,

ppl-

4W --.-

6- .A

ELEMENTS OF ATOMIC PHYSICSby DAVID C. PEASLEE, Dept. of Physics, Purdue University

This is a basic text for courses in Atomic Physics or Atomic Structure, andexcellent reference for courses in Atomic Spectra or Properties of Matter. Thetext starts with the classical picture of atoms as hard spheres; emphasizes experi-mental results and their theoretical interpretations and concludes with a fullydeveloped quantum mechanical model of the atom. Inductive logical order isfollowed throughout (i.e., black body radiation is discussed in the final chapteras an application of wave mechanics, and the Bohr-Sommerfield atomic modelis mentioned only briefly.) It achieves unusual continuity and unity by treatingatomic physics as a single closed subject that is not developing per se. The bookis designed to form a bridge in the student's training between the classical intro-ductory courses and more advanced modern topics.

6" x 9" * 416 pages * Published 1955

ADVANCED ORGANIC CHEMISTRYby E. EARL ROYALS, Emory University

This is a textbook designed to provide the advanced student with a mature graspof the science. The emphasis is on transformation of organic matter, presentedin such a manner as to reveal fundamental behavior patterns of organic matterin terms of the unifying principles of electronic theory. Discussions of mecha-'nisms and the application of organic reactions to synthesis and degradation arenot separated; every effort is made to relate mechanistic considerations to thepractical problems of synthesis and analysis. Electronic theory is presented as anaid to understanding and memory, not as a predictive tool. This book representsthe first serious attempt to present a practically useful integration of descriptivefact and unifying theory at the advanced level of organic chemistry.

6" x 9" * 948 pages * Published 1954

PLANT TAXONOMYby EARL L. CORE, West Virginia University

This is a basic text for all courses in Plant Taxonomy, Systematic Botany andPlant Classification in departments of Biology, Botany and Plant Science. Itapproaches the study of plant taxonomy from the historical point of view. Thevarious principles are presented in the order in which they became known to man.The second part of the book treats the principal families of vascular plants inconcise form under such topics as roots, stems, leaves, inflorescences, flowers andfruits. Over 200 families are discussed so that intructors in different parts ofthe country may select families important to their locales. The organization ofthe material makes the text adaptable to courses of almost any length andemphasis.

6" x 9" * 480 pages * Published 1955

22 APRIL 1955 lA22 APRIL 1955 IA

G.A.B. Interference Filters PHOTOVOLT(Made in Switzerland) Exposure Photometer Mod. 200-M

for isolating narrow spectral bands forP H 0 T O M I C R 00 R A P H Y

LY I Id I ;__

Spectral Range: 400-900 millimicronsSpectral Width: 12-15 rntL, Transm.: 45-50%

Size: 2" x 2". Other sizes on order.ForFlame Photometry and Color Densitometry 7

Microscopy and PhotomicrographyColorimetry and Fluorimetry

a4o In reflectometry. light scattering measurements,mucrocolorimetry, refractometry, polarimetry, and In allother fields requiring monochromatic light in the visibleand near-infrared range. Accurate determination of exposure time InWrite for Bulletin #1180 to black-and-white and color photomicrography

Write for Bulletin #810 to Price $92.00PHOTOVOLT CORP. PHOTOVOLT COR*P.

95 Madison Ave. New York 16, N. Yi. 95 Madis A N Yr 1 N Y.

THE ~ FRACTION COLLECTOR FOR CHROMATOGRAPHYUIMPORTANTTwo METHODS OF COLLECTION ... timed-flow and volu-

OffEED Y THE metric. FULLY AUTOMATIC.. .whether set for timed-flow$kCQIMODL 11200 or volumetric operation. COLLECTS Up To 400 SAMPLES200 resulting in sharper differentiation of components.RE'ADILY INTERCHANGEABLE RECEIVER P~ES... afford-

A ~~~~ing widely varied volumes per fraction. FOUR CHROMATOGRAPHICCOLUMNS CAN BE OPERATED SIMULTANEOUSLY... each delivering intoan individual row of tubes. COLLECTS SAMPLES ON A VOLUME BASISAS SMALL As 3cc ... and up to 90 ml. with standard receiver plates.Timed Interval Between Tubes from 30 Seconds to 50 Minutes.

I " 1llSamples in Full View for Ready Observation. ACURA ... andCompletely Dependable in Performance.

STANDARD EQUIPMENT: Stand with four stainless steel support posts.Heavy duty worm gear reduction motor with indexingmechanism. Two receiver plates: one holding 400 13 mmtubes, the other 100 25 mm tubes. Three volumetricsiphon assemblies. Timer/Controller.

PRICE: RECO Model F1200 Fraction Collector, complete $525.00Literature describing the complete line of RECO Paper Partition

Write for Brochure Chromatographic Equipment and Supplies sent on request.FIO describingthe Reco Fraction MANUFACTURERCollector. £~ACH EQUIPMENT corporation

IRD STREET e OAKLAND, CALIFORNIA

SCIENCE, VOL. 1212A

O-A

PRECISION CIRCULARWARBURG APPARATUS

'I AMOMI

A widely used model, the Precision 20-unit Circular War-burg Apparatus is engineered for sturdiness and simplicity.Embodying a fully adjustable speed and stroke, simplifiedplanar shaking motion, large volume bath, accurate tem-perature control (ambient to 500C, ± 0.050, this compactunit has almost limitless applications in the busy laboratory.The procedures of Warburg, Barcroft, Burk, Dixon-Keilin,Elliot, Krebs, Summerson are but a few of the studies inwhich this instrument excels.

WARBURG ACCESSORIESIn addition to a wide variety of only the finest WarburgApparatus, our complete Warburg Technical Service in-cludes the maintenance of a corps of highly skilled glass-blowers who specialize in the manufacture and repair ofglass manometers and vessels of all types. Your inquiriesare invited and estimates will be promptly furnished.

Deliveries on all Warburg Apparatusand accessories are from stock. Writetoday for detailed information I

PRECISION REFRIGERATEDWARBURG APPARATUS

WI

Embodying all of the features of the circularmodel the Precision Refrigerated unit offers agreater temperature range (10°C to 500C, ±0.05 0). Refrigeration unit is compactly housedin cabinet which serves as base for instrument.Cooling is controlled by a separate switch. Solon-oid valve-actuated by a thermo regulator-admits refrigerant to cooling coil.

-.M

R7 E~

ITELEPHONES:NEW YORK

LExington 2-1311NEW JERSEY

ELizabeth 4-1330

r -I/ E. MACHLETr & SON %ESTABLISHED 1 B97

A COMPLETE SERVICE FOR THE LABORATORYAPPARATUS * INSTRUMENTS * CHEMICALS * GLASS BLOWING220 EAST 23rd STREET * NEW YORK 10, N. Y.

CABLE:IMSONGLAS |

TELETYPE: |N. Y. 1-2444

SCIENCE is published weekly by the AAAS, 1515 Massachusetts Ave., NW, Washington 5, D. C. Entered at the Lancaster, Pa., Post Offce as secondclass matter under the act of 3 March 18 79. Annual subscriptions: $7.50; foreign postage, outside the Pan-American Union, $1; Canadian postage, 50¢.

22 APRrr 1955 3A

ot..

r-- FLUORIDATION AS A PUBLIC HEALTH MEASUREEditor: James H. Shaw, Harvard School of Dental Medicine

6 x 9 inches, 240 pagres, 24 illustrations, index, clothbound, 1954

Price $4.50. AAAS Members' prepaid order price $4.00.A symposium volume of the American Association

for the Advancement of ScienceThe fluoridation of water supplies has become a subject of intense national interest. This

volume offers a comprehensive evaluation of our present knowledge of the benefits and possi-ble dangers of fluoride ingestion and the importance of fluoridation in dental caries and hu-man health. Both scientific research and engineering implementation are covered.

This book will prove to be an invaluable reference for the public health worker, the sani-tarian, the civic official, the waterworks engineer, and the interested layman. The eminent

: qualifications of each of the chapter auithors should be sufficient to inspire confidence inthe unbiased authenticity of the material.

TABLE OF CONTENTSResume of Dental Benefits of Fluoride Ingestion

Acute Fluoride Poisoning and Crippling ClhronicFluorosis

Metabolism of Inorganic Fluorides

Some Public Health Aspects of WVater Fluoridation

Medical Aspects of Excessive Fluoride in a WVaterSupply: A Ten-Year Study

A Long-Term Medical Study of Children in a

Community with a Fluoridated Watcr Supply

The External Action of Fluorides and Other Agentson the Teeth in the Prevention of Tooth Decay

Relative Mierits of Various Fluoridation Vehicles

Engineering Aspects of Fluoridation Installation

Deternmination of Fluorides in Water

Some Chemical Aspects of Water Fluoridation

ZACHARY M. STADT, Contra Costa County HealthDepartment, Martinez, California

GERALD J. Cox, University of Pittsburgh

EDWARD J. LARCENT, University of Cincinnati

HAROLD C. HODGE and FRANK A. SMITH, Univer-sity of Rochester

N. C. LEON E F. A. ARNOLD, JR., E. R. ZIMMER-MAN and P. B. GEISER, National Institute of DentalResearch, National Institutes of Health; J. E. LIEB-ERMAN, Office of Biometry, National Institutes ofHealth; M. B. SHIIMKIN, National Cancer Institute,National Institutes of Health; and C. A. STEVEN-SON, Scott and WVhite Clinic, Temple, Texas

EDWARD R. SCHLESINGER, New York State Depart-ment of Ilealth and Union University; DAVID E.OVERTON and HELEN C. CHASE, Newburgh-Kings-ton Fluoridation Survey Project

BASIL G. BIBBY, Eastman Dental Dispensary andUniversity of Rochester, and FINN BRUDEVOLD,Eastman Dental Dispensary, Rochester, New York

REIDAR F. SOGNNAES, Hlarvard University

0. J. MUEGGE, WVisconsin State Board of Health,Madison, Wisconsin

JAMES G. WEART, Department of Public Health ofthe State of Illinois, Springfield, Illinois

M. STARR NICHOLS, University of Wisconsin andState Laboratory of Hygiene, Madison, Wisconsin

American Association for the Advancement of Science1515 Massachusetts Avenue, N.W., Washington 5, D.C.

English Agents: Bailey Bros. & Swinfen, Ltd., 46, St. Giles High Street, London, W. C. 2...4----------- G. ....--,----___________...W------------------ ....... - - - - --- _________ _ _ -_,

000060100000000000000000000

Ii

0

:1Arl

-1

0-11

I

0

0

I

0I

0

0

0

0

0

4A $c,lxs?cz VOL, 121

ician!

ige-instead of tube-lividual coarse and fin(single, clutch-operatec

U KE. Leltz, Inc., Dept.468 Fourth Ave., New York 16, N. Y.

Please send me your brochure on the new LeitzLABOLUX.

Name

"ny Street

City State

I- - - - - - - - - - - - - - - - -

22 APRI 1955 5A

~~~~~~~~~~~~~~~~~~~~~a am

OFFERS OPTIMUM RESOLVING POWERAND HIGHEST USEFUL MAGNIFICATION

Now, at a price within range of every user, the"Ortho-Illuminator B" converts any make orBul-nFaremodel microscope into an integrated unit withBul-nFa re

built-in illumination on the Koehler principle. De- Of the Ortho-Illuminator Bsigned primarily for visual microscopy or use with INTENSITY FINGERTIP CONTROL withexisting photomicrography equipment, the new constant color temperatureunit embodies the same precision, operating prin-

FITR Dalg,gre,ed puciples and performance found in standard Ortho- FITR alight,blnea 20gren redorplusIlluminator and Orthophot models. It is instantly peratureadaptable to widely different operational require-

FILOFIE DAPRG fousdments - simply and quickly aligned with any FinpaeLD of-VIeW DIAPHRAG focussabeadmicroscope- adjusted, removed or repositioned ienfpalaeo ifthe objenetndjsalepanedwithout disturbing alignment. Unequalled versa- controlstility for instant command of brightfield, dark.- Ideal for photomicrography, micro-pro-field, phase contrast, polarized or fluorescent light. jection, drawing, measuring or counting,Constant color temperature is maintained while and demonstrations to small groups.controlling full range of intensity for illumnination For complete details on the "Orfho-lllu-of maximum numerical aperture obtainable with minator B" and accessories, request Bulle-standard Abbe, Aplanatic or Achromatic con- tin No. 401-L and price list.densers. This assures optimum resolution discern-ible by the human eye and on photographic film. _______________

Write for descriptive data

16th & Carolina StreetsSan Francisco 19, Califomnia

SCIENCE, VOL. 1216A

A New Flame Photometer

designed for the people who will use it

* as fast as 50 seconds per analysis* as accurate as + 1%a as dependable as Perkin-Elmer can make it (leader in

the field for 10 years-with 1000 proved instruments)* as simple as dialing a phonePerkin-Elmer's new MODEL 146 FLAME PHOTOMETER has beenfunctionally designed to give performance with convenience.All controls are grouped at the operator's fingertips. Easy-to-read numerical counters replace vernier dials. Drift-free, vibra-tion-proof electronics give maximum sensitivity and stability.Any gas: natural, city, propane, or acetylene may be used.A prism monochromator permits (1) analysis of any element

emitting in the visible, (2) high discrimination, (3) rapidselection.The MODEL 146 FLAME PHOTOMETER with its attractive,

colorful design, its assured performance characteristics-is avaluable addition to any laboratory.

THE PERKIN-ELMER CORPORATIONNORWALK * CONNECTICUT

Offices in: Chicago, New Orleans, Silver Spring, Md.

1. Thumb-operated wheelgive fast, sure control forinternal standard measurements; numericalcounters permit instantreadings.

~~~~~~~~~~~~~~~~.~~~~~~~~~~~~~~~ s -

2. Sliding dial permits quick choice ofemission wavelengths.

SCIENCE) VOL. 121

:.,:; : : ^:::oo:vn Xisi;;;......................>:xx:.,