adjustable from 0.5 to 50 psec. Rise timeis variable from 0.15 to 2 osec, fall timefrom 0.15 to 2 psec. (Rese Engineering,Inc., Dept. S591)

* PLANIMETER for integrating linear strip-chart records is designed to accept chartsup to 3 7/16 in. wide. The curve is fol-lowed by a pointer that is positioned bya hand-controlled knob. A variable-speed, foot-control drive permits theoperator to adjust the speed of traverseto his ability to follow the curve. Opti-mum accuracy is ± 0.1 percent. A similarinstrument is available for integratingsquare-root charts. (Librascope, Inc.,Dept. S592)

E DIRECT-RECORDING OSCILLOGRAPH pro-vides 20 recording speeds from approxi-mately 0.08 to 128 in./sec. Illuminationof the galvanometers is provided by asingle source whose intensity is adjustedautomatically to each recording speedrange. Up to 50 recording channels maybe provided. Frequencies as high as 3000.cy/sec and trace velocities above 30,000in./sec can be recorded and viewed im-mediately without processing. (Midwest-ern Instruments, Dept. S582)

* VOLTAGE REFERENCE SUPPLY is designedto replace No. 6 dry cells in instrumentsand controls. The supply, designed to re-semble the dry cell and substitute for itwith no modification requirements, sup-plies 1.5 v at 6 ma with 0.25 percent sta-bility to input variations from 108 to125 v. (Performance Measurements Co.,Dept. S604)

* DIFFERENTIAL PRESSURE TRANSDUCERmeasures pressures in full-scale rangesfrom ± 0.1 to ± 100 lb/in2. The measure-ment principle is a magnetic pressure-sensing diaphragm operating betweencoils in a magnetic reluctance systemwith two active arms. Full scale output istypically 40 mv/v. Linearity is + 1 per-cent of range, and hysteresis error iswithin 1 percent of maximum pressureexcursion. (Pace Engineering Co., Dept.S598)

* RECORDING BALANCE, manufactured bySartorius-Gbttingen, is available inranges from 0 to 100 jig to 0 to 10,000pg. The balance has a quartz beam sus-pended from a 7-mil torsion wire. Theobject to be weighed is suspended fromthe end of the beam and counterbal-anced. Changes in weight are counter-acted by magnetic force to maintain theposition of the beam. The change in cur-rent required to effect compensation canbe used to record weight changes. Thebalance may be operated in vacuum.(C. A. Brinkman and Co., Inc., Dept.S594)

JOSHUA STERNNational Bureau of Standards

NUCLEIC ACIDSfor 'growth studies.

YEAST ADENYLIC ACIDfor its inhibition of tumor growth in mice.

PURINE COMPOUNDSfor growth inhibition studies.

N.ETHYL MALEIMIDEfor its reported antimitotic effect in tissue culture ofchick fibroblast.

TRIPHENYL TETRAZOLIUM CHLORIDEfor determination of cancerous tissue.

TRIPHOSADENC(Schwarz Brand of Adenosine Triphosphate) forphosphorylation studies.

These Schwarz fine chemicals satisfy the exacting requirements ofproducts intended for laboratory and biochemical use.

To assure the user of highest quality and purity, rigid specifica-tions in accordance with latest literature are established for eachproduct, each lot is carefully analyzed and checked before ship-ment, complete records are permanently kept, and an analysis isfurnished the user if desired.Quantity production resulting from the wide preference and de-mand for Schwarz high-quality biochemicals provides ample sup-plies at low cost. Write for informative technical bulletins, specifi-cations, references to literature and latest complete price list.

SCHWARZ LABORATORIES, INC.Leading Manufacturers of Yeast Biochemical

and Fine Chemicals230 WASHINGTON STREET, MOUNT VERNON, NEW YORK

13 SEPTEMBER 1957

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