®
VITREOSIL
INSTRUMENTATION
for your most exacting
LABORATORY NEEDS VITREOSIL TUBING TRANSPARENT · SAND SURFACE GLAZED OR SATIN SURFACED
CHARACTERISTICS-Chemical and catalytic inertness. Usefulness up to 1000°C and under extreme thermal shock. Homogeneity and freedom from metallic impuri ties. Best ultra-violet trans mission (in transparent quality). STOCK SIZES, Available in all normal lengths. BULLETIN 22 for speci fication and prices.
VITREOSIL CRUCIBLES · DISHES · TRAYS MUFFLES · POTS · RETORTS ·
TANKS
CRUCIBLES: Permit production of compounds of real purity. No material absorption, noncatalytic, non-porous. Can be wire-wound for electrical heating. Glazed and unglazed. Im mune to extreme chemical, thermal, elec trical conditions. DISHES: For concentra tions, evaporation, crystallizing acid solutions. All sizes and types. TRAYS: Many sizes available from stock. Special sizes can be supplied promptly. BULLE TIN 21 for specification and prices.
VITREOSIL ELECTRIC IMMERSION HEATERS BALL & SOCKET JOINTS · STANDARD TAPER JOINTS · GRADED SEALS
CORROSION RESISTANT-impervious to all organic and inorganic chemi cals even at very high temperatures regardless of the concentration of the chemical, except strong caustics and hydrofluoric acid. EXCELLENT HIGH TEMPERATURE CHARACTERISTICS · EXCELLENT STRENGTH · IMPERMEABLE · OUT STANDING ELECTRIC PROPERTIES. Specify item for bulletin and prices.
VITREOSIL
THERMAL AMERICAN FUSED QUARTZ CO., INC. 18-20 Salem Street, Dover, N e w Jersey Please send Bulletin N o .
, or
Bulletin on Company— N a m e and Title Street City
Zone
State
Circle No. 50 A-1, 50 A-2 on Readers' Service Card, page 53 A
50 A
ciple at least, become relatively inde pendent of feed-screw errors. The present report deals with a system which discards intermittent advance of the blank. The blank carriage is moved uniformly and continuously, while it and the ruling diamond are kept phased to gether at all times by a correction servooperated from interference fringes. The new method avoids transients arising from the starting and stopping of a heavy blank carriage at the begin ning and end of each ruling stroke. This innovation alone has resulted in a doubling of the precision of control. In terferometer mirrors are mounted on the blank carriage and motion of the latter causes interference fringes to pass across a photoelectric pickup. The low fre quency a.c. so produced is subjected to a constant phase comparison with a standard signal of equal amplitude that indicates the phase of the periodic dia mond motion involved in the ruling stroke. As the blank moves forward at constant speed, the diamond moves uni formly across it while ruling. Devia tions in phase greater than about V « wave (2.5 X 10~7 inch of blank motion) produce difference currents, wh'ch, when amplified and fed to a balancing motor, apply through a mechanical differential the needed acceleration or retardation to the screw which advances the blank carriage. As before, green light from a Meggers arc lamp containing pure isotope Hg~198 is used in the interferometric control. A new linkage converts the simple har monic motion for driving the cutting diamond into linear motion by means of, a fixed cam. The latter is sufficient to introduce the small correction. The new monorail suspension for carrying the diamond carriage is an enchanting development in itself. Some of the scientific detective work involved in this development is no less intriguing. For example, very small, but nevertheless troublesome, temperature disturbances gave rise to persistent errors. In the oil bath surrounding the engine, tem peratures are continuously recorded to 0.001 ° C , and held to closer than 0.005° C , but the disturbances indicated the presence of local deviations of a few hun dredths of a degree. When the coeffi cients of expansion of all materials were applied to the various structural ele ments, it was found that 22 inches of tool steel could account for the ruling error. This proved to be the distance between the reference mirror of the grat ing carriage interferometer and the plane of the diamond carriage! This distance is now being reduced to zero. This article should be read by all who desire a perfect example of the best practices in modern instrumentation and automatic control.
ILLCO-WAY ionXchange LABORATORY SIZE OF CARTRIDGE DE-IONIZER GIVES MINERAL-FREE WATER The latest development in ionXchange equipment is the mixed-bed de-ionizer, which combines both anion and cation resins in one vessel or tank. The unit shown below is a miniature model of such a de-ionizer, made up in such a manner as to be an ideal accessory in any laboratory where mineralfree water is wanted occasionally in compara tively small quantities. The ILLCO-WAY Cartridge De-Ionizer consists of a plastic tubular column containing 3 lbs. of mixed resin. When the resins are exhausted, as shown by a change in color, the entire cartridge can be discarded and a fresh one substituted. N o electrical connections are needed. The column can be clamped, as shown, in any convenient location or manner. RESEARCH MODEL Produces water comparable to that obtained by triple dis tillation. Removes all ionizable solids, including silica and CO2.
CAPACITY — 450 grains FLOW RATE - 5 gPh PRICE (FOB Rockford) — $12.50 BRACKET (Extra) — $5.00 UNIVERSAL MODEL Produces water comparable to that obtained by single dis tillation. Removes all ionizable solids except silica and CO..
CAPACITY - 900 grains FLOW R A T E - 5 g P h PRICE (FOB Roekford)-$9.75 BRACKET (Extra) — $5.00 Write for fully descriptive literature Bulletin C A - 2 5 4
ILLINOIS WATER TREATMENT CO.
ionXchange 835 CEDAR ST.
ILLCO-WAY
ROCKFORD, ILLINOIS
NEW YORK OFFICE: 141 Ε. 44TH ST., NEW YORK 17, N.Y. CANADIAN DIST: PUMPS & SOFTENERS, LTD. LONDON, ONT.
Circle No. 50 A-3 on Readers' Service Card, page 53 A
ANALYTICAL
CHEMISTRY
