NEW POWER AND PRECISION FOR VISCOUS MIXTURES
T h e HELLER 6 T 6 0 Heavy-Duty S t i r r e r f o r o n l y $ 1 7 7 ! The new Heller 6T60 gives precise speed control with a 1/20 H P motor having seven times the torque of the famous GT21 L a b Stirrer, of which more than 25,000 have been sold. Solid-state m o t o r controller provides adjustable speed with automatic correction for changing viscosity and line voltage fluctuations. T w o output shafts are rated 0-1800 R P M at 1.8 inch-lbs. torque and 0-180 R P M at 12 inch-lbs. torque through 10:1 gearhead. Highrange control doubles maximum speeds at reduced torque. Controller operates o n standard 100-130 volt 50-60 Hz A C . Price includes motor, controller, 6" stainless steel propeller, coupling, 3-jaw chuck, motor mounting bracket and base plate with rod for lab stand clamp, and regular motor base plate for shelf or wall mounting. Heller GT21 1/40 H P mixer includes chuck, propeller, paddle, pulley and mounting accessories for $117. F o r details, write for Bulletin 639. A variable through leading lab supply dealers
G. K. HELLER CORP. 2673 S. Western Street, Las Vegas, Nev. 89114 7 Mayflower Place, Floral Park, L.I., N.Y. 11001 Circle No. 37 on Readers' Service Card
Portable • Complete • Low Cost DELMAR BASIC HIGH-VACUUM SYSTEM Convenient and economical for: • student use • demonstrations • research TYPICAL APPLICATIONS • handling gaseous material • preparing geochemical samples • effecting molecular distributions • preparing samples for nuclear magnetic and electron spin resonance studies Comes complete (as illustrated) with rack and all glass components including diffusion pump, manifold, McLeod gauge, manometer, traps, adapters and hardware.
For complete details, ask for Bulletin AC-60. Write to Coleman Instruments Division of t h e Perkin-Elmer Corporation, 42 Madison Street, M a y w o o d , Illinois 60153.
PERKIN-ELMER Circle No. 26 on Readers' Service Card
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ANALYTICAL CHEMISTRY
New Products Oscillator
Model 204D has an 80 dB attenuator range in 10 dB steps with an accuracy of ± 3 % (+10 db through - 6 0 dB range; ± 5 % on —70 dB range). A >10 dB vernier provides overlap in any range. The sine wave generated by the oscillator has less than 0.1% distortion at frequencies between 30 Hz and 100 Hz (linearly derated to
