AP'PARATUS I D n m I L L m -
Multiple-Extraction Rack for Chemical Analysis of Rubber Products
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.Lllllr~ V I U ~ , u i z t u U J L~LGUCS L I L ~ I U I YBI-~U. 11 p m e a on s r a m 36 inches high, a11 units are at a comfortable height to facilitate handling and observation. Water supply and discharge manifolds serve the extraction condensers, the water supply to each condenser being controlled by 8. needle valve. Condensers conform to A. S. T. M. Method
Utilizing extraction condensers, as specified in A. S. T. M. Designation D297-41T for the chemical analysis of rubber products, the multiple unit electrically heated extraction racks developed by the Precision Scientific Co., Chicago, are especially applicable to routine extractions incident to the produotion of synthetic rubber. Faced with the difficult problem of installing 192 extraction units in one laboratory where space was none too plentiful, the technicians of an important producer of synthetic rubber found no practical solution until the design, exemplified by the accompanying photographs, was submitted. The multiple assembly, consisting of 48 extraction units, is composed of two sets of 24 units each, arranged hack-to-back; each set is composed of two banks of 12 units each, one deck above the other. The 48-unit assembly is only 48 inches long,
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INDUSTRIAL AND ENGINEERING CHEMISTRY
DZ97-41T. They can he used with 250- or 400-ml. flasks, and are spaced on 3.375-inch centers. To permit elevation of each condenser for placement or removal of the flask, the condenser overflow pipe telescopes into a vertical pipe communicating with the water discharge manifold, while the connection between condenser inlet and water supply valve is flexible synthetic rubber tubing. Electrically heated hot plate tops are heat-treated heavy cast iron, with strip units fastened to the underside, and the remaining space within the hot plate housing is packed with thermal insulating material to promote heat efficiency. Each hot plate includes a. 3-heat switch.
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knobs st the front I f the condenser section allow the selection of capacitance values from 1 to 60 microfarads in steps of 1 microfarad. Ten knobs allow selection of resistance values from 1 t o
insulated kni6 switches to assure'certaint"v of contact add frzedom from trouble. The main panel is supplied with an oscillograph, 60 that the current, duration, and wave form of an average individual discharge e m he studied. This is useful BS a mean8 of Dredicting
Multisource Unit A new electrical source unit for spectrogaphic analysis has been announced by the Harry W. Dietert Co., Detroit, Mich., and its associate, the Applied Research Laboratories, Glendale, Calif. The unit is said to combine the functions of the couventiond direct current arc, alternating current arc, and highvoltage condensed spark units, and to go beyond them in providing precisely controlled excitation suitable for all types of analysis.
accuracy on this account. A Dhbse eonthl knoh,ucouDlled di-
Hardness Tester Clark Instrument, Inc., Dearhorn, Mich., announces au im. . . . . 4 h n w h a o o tester tnoiefnr Rockwell D,-L.rrc.ll tnriinn in th-no mnrldr moved hardness for testing in three models, USS, US12, and US16. The instrument issaid to embody a number of features contributing to accuracy of measurement and speed of operation. Among these are a frictionless spindle which provides a correct minor load st all times, zero drag trip which eliminates friction or drag on the loading h e m and enmres consistent accuracy of the major load, a dial indicator adjustment affording a convenient, simple means of maintaining accumcy of readings, and a minor load adjustment. Other features are fully enclosed elevating screw with selflubricating oil reservoir, and an adjustable steady rest. The instrument is supplied complete with diamond cone penetrator and steel hall penetrators for Rockwell testing on C, B, and mast other standard Rockwell scales.
With this unit the three factors of an electrical circuit-resistance, inductance, and rapacitance-may he set and precisely controlled t o selected values over wide ranges. By virtue of the wide variation in excitation conditions obtainable, either very arclike or sparklike spectra, with all variations in between, may he had. The fine adjustment and control of the discharge afforded by the adjustable resistance, inductance, and capacitance mean that the Multisource excitation combines the sensitivity of the arc with the accuracy of the spark. The unit consists of a main control panel mounted a t the front, and a selector panel mounted a t the side and equipped with pull knahs which allow selection of the condition3 of discharge. Seven
