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SPECTROPHOTOMETER CELLS
Grazing incidence vacuum spectrometer is used in the region below 1200 A. Regardless of the angle of incidence, the readout on a counter remains linear and, once set, is given directly in angstroms. The choice of angle of incidence permits the spectrographer to use that angle which will give him the lowest desired wavelength with a minimum of optical aberration and astigmatism. Spex Industries, Inc. P.O. Box 9 8 , 5 1 4 Martin Place, South Plains, N. J .
439 Digital Deviation Ohmeter T h e instrument measures per cent deviation of an unknown resistance from a s t a n d a r d resistance in steps of 0.01% in the interval of - 9 9 . 9 9 % to + 9 9 . 9 9 % and the resistance range of 100 ohms to 1 megohm. For lower resistance an external power supply is needed. Three measurements can be run per second. T h e s t a n d a r d resistance is a 6-decade unit variable in 1-Ôhm steps u p to 1.2 megohms. Initial accuracy is ± 0 . 0 0 5 % and 0.03% long t e r m . Model D 0 2 4 . Non-Linear Systems, Inc., Del M a r , Calif. 440
β © DUO-SEAL VACUUM PUMPS are designed to fit almost every application better and at less cost . . . in the laboratory, industry and school. Ten different models to choose from . . . capacities from 21 to 1400 liters per minute . . . ultimate pressures from 2 χ 10-2 mm Hg down to 1 χ 10—4mmHg and better . . . two-stage and singlestage mechanical pumps with vented exhaust, and mechanical and diffusion combination pumps.
FEATURING THE SPECTROCELL* *Rectangular Silica Cell, 10 mm, light path, 8 mm inside width, 48 mm height. Working capacity 3 ml. Fits directly in cell carrier furnished with spectrophotometers. Price $25.00.
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- Spectral Range: Transmittance:
Matching Tolerance:
:' 220 mu to 3500 fhu 75% at 220 mu 80% at 240, 270 mu 85% at 300, 350 mu 85% at 1000, 1500 mu 80% at 2700 mu 2% at 220 mu 1% at 240, 270 mu 3% at 1500, 2700 mu
THE ULTRACELL COMPANY P. O. Box 612, Emerson, New Jersey Phone: CO 2-2364 Circle No. 90 on Readers' Service Card 110 A
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ANALYTICAL CHEMISTRY
Power input controller, type 8 0 0 0 , is a redesigned electron, thermally activated stepless power input controller. It is used with flask heaters, heating mantles, heating tapes, water baths, and similar equipment. In addition to the 115-volt-1500-watt model, there is also available a 230-volt model. Thermolyne Corp., P.O. Box 797, 4 6 5 Huff St., Dubuque, Iowa.
441
Over the years, Welch Duo-Seal Pumps have built a world-wide reputa tion for best performance, greatest reliability and quietest operation. When you use a Duo-Seal Pump, you're using For complete specifications and prices, ask for Duo-Seal Catalog
THE WELCH SCIENTIFIC COMPANY Ά
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1521 Sedgwick St. ·
Chicago 10, 111.
Circle No 84 on Readers' Service Card
