QUAIT Y, DEPENDABIlITY,

PERFORMANCE

OMNI - MIXER: A port-able, high-speed instrumentdesigned exclusively by IvanSorvall, Inc. for all labora-tory homogenizing, mixing,emulsifying and difficultdisintegrating work. Spe-cially-shaped, stainless-steel,200-ml mixing chambereasily cooled or heated. Ac-commodates mason jars -

rugged construction * easilycleaned and sterilized.

Wrike for Bulletin SC-96

ULTRA-MICROTOME: 1/40 to 1/2 Micron. Simple tooperate-makes Serial Sectioning for Electron Microscopya routine laboratory technique. Mechanical advancement* collet-type chuck and many other features * Light-weight and portable.

Write for Bulletin SC-95

SUPERSPEED ANGLE CENTRIFUGE: 15,500-rpm-31.000x G-400-ml. Portable, with separate transformer for re-mote control-may be operated in cold room, incubator,etc. Accommodates tubes from 1- to 50-ml (with use ofadapters). Self-balancing, direct drive for smooth, trouble-free operation. "The workhorse of the modern researchlaboratory."

Write for Bulletin SC-91

M, SP, & SP/X ANGLE CENTRIFUGES: 5,000-rpni-3,500 x G.Type M-Twenty-Seven 15-ml TubesType SP-Six 75-ml TubesType SP/X-Ten 50-ml Tubes and Five 15-ml Tubes. Tubeadapters available for greater versatility. Other sizes of AngleCentrifuges available.

Write for Bulletin SC-91

SUPERSPEED REFRIGERATEDCENTRIFUGE: 15,500-rpm-31,000 x G. Exclusive dualautomatic temperature andholding control establishes andmaintains temperatures downto and below 0°C. No externalpre-cooling of rotors is neces-sary. A large selection of"Servall" rotors, in addition tothe Superspeed Rotor, may beinterchanged easily and rapidlyon the "Servall"-originated di-rect drive. No complicateddrive attachments are requiredin order to obtain the higherspeeds. Maximum capacity atSuperspeeds: 400-ml Maximumcapacity at lower speeds: 2,000-ml The "Servall is the leastexpensive Refrigerated Centri-fuge in the Superspeed Range.

Write for Bulletin SC-91R

ALSO, IVAN SORVALL, INC. ARE SOLE DISTRIBUTORS IN THE UNITEDSTATES AND CANADA FOR LKB PHYSICAL CHEMISTRY INSTRUMENTS.

Designers, Manufacturers and Distributors of "Serv-V V ^ imVC§- all" Specialized Laboratory Instruments Since 1930.

NORWALK * CONNECTICUT

-

The New 71ff3ac

Offers unsurpassed versatility in operation. The RadiRac equipment containsa number of sub-units which can be combined in several ways for the collec-tion of effluents by the

Timed Flow Method ..i ,.J,i;

Volumetric Method Collects in

Drop Count MethodThe most important of the RadiRac sub-units-all of which are available separately-are:

ROTATORTURNTABLE DISKTUBE RACKSCONTROLLERDISTRIBUTORSIPHON ASSEMBLY

consisting of:

SIPHONXI-SIPHON STAND

SAFETY CATCHER 4

DROP COUNTER(in development)

Accessories-also availableoptionally-include:

Dust Cover, Guide Plate,Hose Holder, SpiralGuide, Stands, etc.

]circles

"spirals" Or

MIain Characteristics:

Interchangeable Turntable Disks for 240 12 mm. or 20 mm. o. d.rimmed test tubes up to 200 mm. long. Turntable Disks for othertest tube diameters made to order.

Controller can be set to any time interval from 4 to 60 minutes(at 50 cps). Repeat accuracy is ± 10 seconds. Controller circuitsupplies power to other sub-units requiring electric power. Oper-ates on 110 - 127 - 150 - 190 - 220 - 240 volts 50-60 cpssingle-phase A.C.

Rotator and Distributor actuated by separate, completely de-RadiRac pendable motors for 20 rpm. All switching is done by sealed

mercury switches, allowing equipment to be operated in corrosivelOLLER, and DISTRIBUTOR and explosive atmospheres.ts. pend.) Interchangeable Siphons of 5 ml. and 25 ml. capacity (± 10 °/o).adiRac batch handling of frac- Other capacities available as supplementary equipment.can be placed on the Turntable:tions is performed by a radial Siphon Stand is easily adjusted for different siphon capacities.lelivering tip combined with a Selfcontained sealed mercury switch actuates Rotator and/orks (see illustration). As soon as Distributor stepping mechanisms.Rack have received their frac-k with tubes is easily removed Safety Catcher receives liquid tO be collected if mains powerrocessing, for example analysis. fails, thus prevents flooding of test tubes and loss of often valu-

able effluent.

fN9 LKB-PRODUKTERFabriksakttebolaQ P. O. BOX 120 A35 - STOrTKHO M 12 .SWEENI& 4b . f w I%,erww 9% --4v ,q1 . W *%-. JL. _7 - vj A ssLss - aVv'Lj.jU'

Sole Distributor for U.S. & Canada: Ivan Sorvall Inc., P. 0. Box 230, Norwalk, Conn.

SCIENCE is published weekly by the AAAS, 1515 Massachusetts Ave., NW, Washington 5, D.C. Entered at the Lancaster, Pa., Post Office as second classmatter under the act of 3 March 1879. Annual subscriptions: $7.50; foreign postage, $1; Canadian postage, 50¢.

AUTOMATIC

FRACTION

COLLECTOR

The

TUBE RACKS, CONTR(Pa

provide for the unique R;tions. Ten 24-tube RacksDisk. Distribution of fracmotion of the effluent drotation of the Tube Racthe 24 tubes of a Tubetions, the 4-leg Tube Racfor immediate fraction pi

m

\

21 SEPTEMBER 1956 511

:I

offers a

NEW

and

greatly

improved

PUMP

PLATE

for vacuum

evaporation

or

This new steel pump plate is designed for experi-mental vacuum evaporation and sputtering of metals,vacuum melting of metals, vacuum impregnation, andfor small quantity production. It also facilitates testingelectronics components as required in the study of highaltitude projectiles.

Direct connection may be made to a mechanicalvacuum pump or to an oil diffusion pump backed bya mechanical unit

No. 94206 Cenco Pump Plate without accessories,#1 for connection to mechanical pump, $155.00;

l e CO # 2 for connection to an oil diffusion pump, $157.50.The most complete line ofscientific instruments ond lob- Attend the National Symposium on Vacuum Tech-oratory supplies in the world nique, Sheraton Hotel, Chicago, October 10, 11

and 12, 1956.

Central Scientific Company1718-M IRVING PARK ROAD, CHICAGO 13, ILLINOIS

BRANCHES AND OFFICES-CHICAGO * NEWARK * BOSTONt * BIRMINGHAM * DETROITSANTA CLARA * LOS ANGELES * REFINERY SUPPLY COMPANY-TULSA * HOUSTONCENTRAL SCIENTIFIC CO. OF CANADA, LTD.-TORONTO * MONTREAL o VANCOUVER * OTTAWA

512

melting

SCIENCE, VOL. 124

Rapid centrifugpre

with the Spco Model

UILTRACENTRIFUGE

r

FULLY-AUTOMATIC features make the Spinco UNITModel L Preparative Ultracentrifuge operationally heightself-supervising. Simple speed- and time-controls for insare preset by operator and electronic unit brings ing0s,yrotor to speed, times run, and decelerates with balan(smoothly operating automatic brake. loaded

Various sizes and types of interchangeable rotors rotorsmount in operating chamber with instantaneous to -5coupling. Time between runs, using pre-loaded ro- Intors, is less than a minute. Speed and vacuum are up to

materi,established almost simultaneously. Acceleration Indivimtime for the 40,000-rpm rotor is only four minutes. availal

SAFETY FEATURES include automatic overspeed seconecoverNscutout; interlocks to prevent running at high speeds tion ofwithout vacuum in chamber and prevent breaking 1700 nvacuum or opening chamber while running at high Send fspeeds. Rotor chamber is encased in thick double denai

detailssteel guard.

Spinco4514

IS SELF-CONTAINED, of worktablet, and requires only electric connectionstallation. Spinco electric drive and gear-rstem are of types proved in more than)0 hours of actual field operation. Self-cing feature eliminates weighing ofi tubes. Controllable refrigeration holdsand contents at any temperature downC.operation, the Model L applies forces144,000 times gravity on 162 ml of

ial at a maximum speed of 40,000 rpm.dual rotor tubes have sealing caps-areble in plastic or metal. Rotors provided vacuum seal in quickly-detachablewith integral lifting device.Wide selec-f rotors is available with largest holdingnI-

for

BECKMAN INSTRUMENTS, INC.BELMONT 5. CALIFORNIA

SCIENCE, VOL. 124

PERGAMON TRANSLATION BUREAUof Russian Science, Technology and

MedicinePergamon Press are pleased to announce that in connection with its own translation

programme of books and periodicals from the Russian language, it is now possible to offer itstranslation facilities to outside organizations and individuals.

All translators have been selected on the basis of specialist scientific or medical qualificationin their particular subject in addition to linguistic proficiency. As only translators with the appro-priate scientific or medical qualifications are engaged by Pergamon Press, translations of thehighest standard can be promised.

All translations will be executed rapidly. Charges vary according to the subject and will bequoted on request.

Translations can be pro'vided in the following subjects:

PHYSICS & MATHEMATICS

CHEMISTRY, GEOLOGY AND BIOLOGY

BIOCHEMISTRY & THE MEDICAL SCIENCES

ECONOMICS & THE SOCIAL SCIENCES

TRANSLATION PANELAdditional translators are still required. Scientists, Technologists and

Doctors interested in furthering translations in their subject are invitedto make applications to join the panel. Fees appropriate to first classtranslations will be paid.Applications should be made to:

PERGAMON PRESS, INC.122 East 55th Street, New York 22, N. Y.

21 SEPTEMBER 1956 .547