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NEW PRODUCTS Sequential Air Sampler New unit automatically collects air samples for subsequent analysis of con tamination. Consists of a vacuum pump connected to a special 12-position valve, which in turn is connected to 12 gas collectors or filter holders. The valve is automatically switched from one position to another so that 12 samples are collected in sequence. The unit shuts itself off at the end of
Contamination and Freeze Proof ASCO " Q U O R N " STANDARD T A P E R SLEEVES • No contamination—attacked by metallic sodium only • No seizure or "freezing" • Self-lubricating • No leakage • Heat resistant from —75e C to 300° C • Long life — can be easily cleaned, and used almost in definitely
VARIAN Potentiometer RECORDERS Used by the because
A new development in the field of jointed glassware, the Asco " Q u o r n " Standard Taper Sleeve is an elongated cone of polytetrafluorethylene film, .003" thick. Accurately tapered to fit tightly over the male ground glass cone an extra tight seal is formed with the female cone without the use of grease, and problems of con tamination due to lubricants and leaking ground joints as well as joint seizure now become obsolete.
JOINT
I
thousands . ..
PER
SIZE
DOZEN
10/30 14/35 19/38 24/40 29/42 34/45 40/50 45/50 50/50 55/50
17.10 17.67 18.24 19.95 21.09 22.80 25.08 27.36 30.78 35.34
Vacuum Tight ASCO O - R I N G STANDARD TAPER CONICAL JOINTS
12 samples. Operation is controlled by a dial-adjusted timer. The unit has a miniature positive displacement rotary pump with 17 liter per minute air capacity. Other models have a separate higher capacity pump as a vacuum source. Prices start at $250. Gelman Instrument Co. P-21
1. THEY ARE TRULY
It is now possible to construct glass apparatus which is leakproof at high vacuums (up to 1 χ 10- s mm. Hg.). A new standard of cleanliness is now possible by eliminating the need for highvacuum greases and permitting freedom from atmospheric con tamination. The rubber 0-ring is protected from attacking solvents by the ground tapered surface of the joint.
PORTABLE The Varian G-11A weighs only 15 pounds and can be carried
• Highest quality borosilicate glass construction · Fusible and compatible with pyrex and other borosilicate glass tubing · Reduces expensive breakage · Economical • Rubber O-ring may be removed
anywhere in t h e
ASCO-SEAL, O - R I N G , inner j o i n t o n l y Taper 1 10/30 12/30 1 14/35 19/38 24/40 24 24 24 24 Case 1 23.33 26.35 1 28.94 30.52 33.26
adapted t o extremely varied
34/45 12 22.46
40/50 12 27.11
45/50 12 33.80
50/50 8 24.77
55/50 8 28.15
60/50 8 32.33
laboratory,
plant or field. And because it is a potentiometer recorder, it is h i g h l y sensitive and can be
29/42 24 36.07
recording requirements.
71/60 8 39.38
Varian recorder prices from $365; full-scale balancing time lor2%sec onds; ranges from 0-9 millivolts to 0-100 volts, wide choice of speeds, accessories and charts. Full specifi cations and description available by writing the Instrument Division.
Practical... WATER-COOLED OIL DIFFUSION PUMP • All steel construction · Ultimate vacuum: 5 χ 10-6 mm. · Two-stage • Requires only 15 ml of pump fluid • Easy to clean · Light, portable • Speed: 15 liters per second at 10·4 mm.
LaPine-Leybold
Fills the need for simple economical attainment of high vacuum operating pressures at the rate of 15 liters per second. Built of carbon steel, the ASCO 1" Diffusion Pump will operate against a forepressure of 0.5 mm, permitting operation with any standard single-stage mechanical pump.
each * 7 6
00
ARTHUR F. SMITH CO. 311 ALEXANDER ST., ROCHESTER 4, Ν. Υ. Circle No. 141 on Readers' Service Card 108
A
·
ANALYTICAL CHEMISTRY
crystal
lattice
kits
enable building of models to show sys tematic arrangement of crystals and properties such as periodicity and sym metry. Kits have red, white, and green spheres, steel needles with magnetic bases, rubber washers for positioning balls, and a steel base plate. Arthur S. LaPine and Co. P-22 Bench Model Centrifuge Versa-fuge superspeed model has built-in safety shield and five inter-
VARIAN associates PALO ALTO 4 , C A L I F O R N I A Circle No. 13 on Readers' Service Card
