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makes work with paraffin-embedded fissues quickand easy. Great for cutting large blocks into smallones; for mounting blocks on a microtome objectdisc; for squiaring up blocks; for separating ribbonsin a water bath . . . Hollow stainless steel handledoesn't heat up - easy to keep knife at the righttemperature. When not in use lay knife in saddlerest-Blade UP indicates knife hot; Blade DOWN,knife cold.

ICJOl microslide dryerdelivers slides ready for staining in 7 minutes! Justdrop slides, in an Autotechnicon Slide Carrier, into thehatch, flip the switch and close the cover. A steadycurrent of warm, filtered air blowing over the slidescarries away all moisture, leaving them bone-dry anddust-free. The filter is replaceable. There's no distor-tion, either - the warm clean air is well below themelting point of paraffin.

iconzhfWfcwater bathinsures smooth, even spreading of your tissue ribbons.The water temperature is just right- never too hot ortoo cold, thermostatically held at any set temperaturefrom 200 to 60°C. There's no melting paraffin to dis-tort tissues- no folds or wrinkles, no bubbles due tofrequent water change. Temperature stays constant,day-in, day-out. And it's easy to see your sectionsagainst the dull finished black interior of the bath.

wSize: 103/4 Diam; 33/4" HighSturdy; durable; water andxylolproof finish.'I 12 A ,_-l. A*e %,e THE TECHNICON COMPANY

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How to experiment . . . and still be sure!When one qualified investigator can repeat and verify theoriginal observations of another, the cause of science isserved.

Thus, both pioneering research and routine control testsdepend on reliable materials as well as methods. It is forthis reason that Pyrex brand laboratory glassware has be-come standard in most laboratories.When you start an experiment using Pyrex ware, you

can be sure that variables are not introduced by the equip-ment. Its high chemical stability provides the necessaryprotection against contamination. And because Pyrex brandapparatus is designed to withstand both mechanical andthermal shock, you get dependable, long-term performance.

In addition, the 40 years of experience in the design andproduction of Pyrex brand laboratory ware make it possibleto meet the exacting specifications of modern science.

Pyrex brand laboratory glassware frees you to investigatethe unknown with confidence. Your laboratory supplydealer stocks it for your convenience. And as alwaysCorning means research in glass.

For dependable accLuracy-Pyrexbrand volumetric fl- sks ..nd pipettesare made to ch-ss "A" tolerances asspecified by NBS circular C434.

Corning Glass WorksCorning, New York

PYREX® laboratory wvare . ..

.... the tested tool of modern research

19 NOVEMBER 1954 1A

1MICROBIOLOGY and I

TISSUE CULTUREThe following Schwarz Preparations are available toassist and extend studies in metabolic and enzymicfunctions:

ADENOSINE PHOSPHATESNUCLEIC ACIDS AND METALLIC NUCLEATESNUCLEOTIDES AND NUCLEOSIDESPURINES AND PYRIMIDINESSUGARS AND SUGAR PHOSPHATESGLUTATHIONE COMPOUNDSSULFHYDRYL REAGENTSTHYMIDIN ECOZYMASE

AND D-AMINO ACIDS, Optically StandardizedRADIOCHEMICALS, Isotopically Labeled with C14 or S3S

These Schwarz Preparationls meet the exacting require.ments of products intended for use in biochemical re.search. Write for informative technical bulletins, com-plete specifications and references to literature. OL 3so

SCHWARZ LABORATORIES, INC.Leading Manufacturers of Yeast Biochemicals and Fine Chemicals

230 Washington Street, Mount Vernon, N. Y.

More Precision inAir Conditioning

Niagara "Controlled Humidity" Method provides airat precise conditions of temperature and moisturecontent.

In the range from below 320 F. to 1400 F. you mayhave constant conditions within tolerances of 10 F.and 2% R. H. with control by thermostats alone...simple and inexpensive... no moisture sensitive in-struments needed.

This Method uses "HYGROL" liquid absorbentto remove moisture from the air directly. Operationis automatic; the absorbent is re-concentrated, by anew, reliable method, at the same rate as it becomesdiluted.

Use it for drying pro-cesses, preventing moist-ure damage to instrumentsor hygroscopic materials,controlled atmospheres fortests and experiments.Unit capacity ranges up to20,000 c. f. m.

Write for Bulletins No.121, 122, 125; addressNiagara Blower Co., Dept.SW 405 Leington Ave.,New York 17, Y.

Write for BrochureFIO describingthe Reco FractionCollector.

FRACTION COLLECTOR FOR CHROMATOGRAPHY- IMP TANT f\ Two METHODS OF COLLECTION... timed-flow and volu-WEES metric. FULLY AUTOMATIC ... .whether set for timed-flow

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--- /or volumetric operation. COLLECTS UP To 400 SAMPLESh/ . .. resulting in sharper differentiation of components.

READILY INTERCHANGEABLE RECEIVER PLATES ... afford-ing widely varied volumes per fraction. FouR CHROMATOGRAPHICCOLUMNS CAN BE OPERATED SIMULTANEOUSLY ... each delivering into

T_ an individual row of tubes. COLLECTS SAMPLES ON A VOLUME BASISAS SMALL AS 3cc ... and up to 90 ml. with standard receiver plates.

X Timed Interval Between Tubes from 30 Seconds to 50 Minutes.

Samples in Full View for Ready Observation. ACCURATE . .. 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 mm

tubes, the other 100 25 mm tubes. Three volumetric

siphon assemblies. Timer/Controller.<_ PRICE: RECO Model F1200 Fraction Collector, complete $525.00

Literature describing the complete line of RECO Paper PartitionChromatographic Equipment and Supplies sent on request.

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2A SCIENCE, VOL. 120

LARGE CYLINDERSfor

COMMERCIAL USEAmple stocks in

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of all gases car-

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MEDIUM-SIZECYLINDERS for

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Three different sizesof cylinders contain-

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large commercialcylinders. Thesecylinders are de-signed for use on

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"LECTURE BOTTLES"for Research Experiments

or ClassroomDemonstrations.71 different gasesof highest purityare available inthese little cylin-ders which have adiameter of 2" andan overall lengthof 151"2.

Matheson's Complet lineof Triple-Tested

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assure yoe of the correct typeef contrel required for each ps.

From Acetylene to Xenon, Matheson has all the gases!Any rare or common gas, or any mixture thereof that youmay need in your work is available from the MathesonCompany.

Our new catalog listing the prices of 71 gases and mixturesalso shows the pressure at which various gases are packed,their purity and the sizes of cylinders in which they maybe obtained, as well as the proper type of pressure or flowcontrol to be used. Write for our new price list datedApril, 1954.

THE MATESON CMPNYINC.EAST RUTHERFORD, N. J. * JOLIET, ILLINOIS

ALL THE CHEMICALS NORMALLYUSED IN THE LABORATORY

are also available fromTHE MATHESON, COLEMAN & BELL

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_SCIENCE is published weekly by the AAAS, 1515 Massachusetts Ave., NW, Washington 5, D. C. Entered at the Lancaster, Pa., Post Office as secondclass matter under the act of March 3, 1879. Annual subscriptions: $7.50; foreign postage, outside the Pan-American Union, $1; Canadian postage, 50¢.

19 NOVEMBER 1954 3A

I

I

FLUORIDATION AS A PUBLIC HEALTH MEASURE-

Editor: James H. Shaw, Harvard School of Dental Medicine

6 x 9 inches, 240 pages, 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 eminentqualifications of each of the chapter authors should be sufficient to inspire confidence inthe unbiased authenticity of the matprial.

TABLE OF CONTENTSResume of Dental Benefits of Fluoride Ingestion

Acute Fluoride Poisoning and Crippling GhronicFluorosis

Mfetabolism of Inorganic Fluorides

Some Public Health Aspects of Water Fluoridation

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

A Long-Term Medical Study of Children in a

Community with a Fluoridated WateT Supply

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

Relative Merits of Various Fluoridation Vehicles

Engineering Aspects of Fluoridation Installation

Determination 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. LARGENT, University of Cincinnati

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

N. C. LEONE, 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. SHIMKIN, National Cancer Institute,National Institutes of Health; and C. A. STEVEN-SON, Scott and White Clinic, Temple, Texas

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

RASCIL G. BIBBY, Eastman Dental Dispensary andUJniversity of Rochester, and FINN BRUDEVOLD,Eastman Dental Dispensary, Rochester, New York

REIDAR F. SOGNNAES, Harvard University

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

J4MES 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.A-SCIENCE, VOL----. 120

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SCIENCE, VOL. 1204A

19 NOVEMBER 1954

G.A.B. Interference Filters(Made in Switzerland)

for isolating narrow spectral bands

Specralange 400900 milimicon

Spectral Width: 12-15 m., Transm.: 45-50%Size: 2" x 2". Other sizes on order.

ForFlame Photometry and Color Densitometry

Microscopy and PhotomicrographyColorimetry and Fluorimetry

also in reflectometry, light scattering measurements,m.icrocollorimetry. refractometry, polarimetry, and in aHother fields requiring monochromatic Ilight in the visibleand near-infrared range.

Write for Bulletin #180 to

PHOTOVOLT CORP.95 Madison Ave. New York 16, N. Y.

PHOTOVOLTExposure Photometer Mod. 200-M

for

PHOTOM ICROGRAPHY

Accurate determination of exposure time inblack-and-white and color photpmicrography

Write for Bulletin #810 to Price $92.00

PHOTOVOLT CORP.95 Madison Ave. New York 16, N. Y.

5A

SLEEPING ACCOMMODATIONS AT 121st AAAS MEETINGBerkeley, California, December 26-31, 1954

The hotel, motel, and dormitory sleeping accommodations-their rates and the application coupon below-are for your convenience in making room reservations in Berkeley. Please send your application directly to theAAAS Housing Bureau and thereby avoid delay and confusion. The experienced Bureau will make assignmentspromptly; a confirmation will be sent you in two weeks or less. Single rooms may become scarce; double roomsfor single occupancy cost more; if possible, share a twin-bedded room with a colleague-and also save. Mail yourapplication now to secure your first choice of desired accommodations. All requests for reservations must give adefinite date and estimated hour of arrival and also probable date of departure.

HOTELS SINGLE DOUBLE TWIN SUITEClaremont 5.00-11.00 8.00-13.00 8.00-13.00 14.00-20.00Durant 4.00- 7.00 6.00- 9.00 6.50-10.00 10.00-16.00Shattuck 5.00-10.00 7.00-10.00 7.50-10.00 10.00-18.00Other hotels 3.00- 5.00 3.50- 5.00 4.00- 6.50 7.00-10.00

(Note: Most hotels have singles without private bath at $2.00-$3.50 per night)

MOTELS FAMILY ROOMSBerkeley Plaza 5.00 6.00 7.00 8.50-12.00California 4.00- 4.50 4.50- 5.00 5.50 6.00- 7.00Golden Bear 4.50- 5.00 5.00- 7.00 6.00- 8.00 7.50-10.00Other motels 4.00- 5.00 4.00- 6.00 5.50- 8.50 6.00-12.00

Dormitory Accommodations: NOTE: The 766 units in the University of California dormitories are primarily for students,younger faculty members, and those not on expense accounts. Occupancy, two persons per room; rate, $2.00 the first night,$1.00 per night thereafter, per person.

International House: Singles only, without private bath, $2.50 per night.

For a discussion of the headquarters of the participating societies and sections, please see Association Affairs, Science, July 23, orThe Scientific Monthly, August.

- ._--_--___ THIS IS YOUR HOUSING RESERVATION COUPON - . -AAAS Housing Bureau2223 Fulton Street Date of Application.Berkeley 4, CaliforniaPlease reserve the following accommodations for the 121st Meeting of the AAAS in Berkeley, Dec. 26-31, 1954:

First Choice .. ..... Second Choice . .............. Third Choice(State name of hotel, motel, or other)

...... Single Room Desired Rate ....... Maximum Rate .......HOTEL AND MOTEL.Single ~~~~~~~~~~~~~ROOMDEPOSIT

...... .Double-bedded Room Desired Rate ....... Maximum Rate ....... $5.00 per reservation or......Twin-bedded Room Desired Rate ....... Maximum Rate ....... $10.00 per room (re-

......Suite Desired Rate ..... Maximum Rate...... fu ndedi fcancelledbefore.......Suit DeiredRate ......................... Maxmum ate Dec.17)...... Dormitory Unit(s)-two persons per room at $2.00 each first night, $1.00 per Make checks payable to

night thereafter. "AAAS Housing Bureau."

The name and address of each person, including yourself, must be listed. Attach list if this space is insufficient.

. .... .... . ..... .... .. ...... .... .. ...... .. .. ...... .. .... .... .... .... .... .... .. .... .. .. .... .. .... .. ...

DATE OF ARRIVAL.DEPARTURE DATE......DEPARTURE.DAT(These must he indicated-add approximate hour, a.m. or p.m.)

ADDRESS ....................................

My society (or sectional interest) is: ....................................................................I (will) (will not) have an automobile at the Meeting.

Mail this now to the Housing Bureau (address above). Enclose hotel or motel room deposit. Make checks payable toAAAS HOUSING BUREAU. Rooms will be assigned and confirmed in order of receipt of reservation.

6A SCIENCE, VOL. 120

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