452
INDUSTRIAL AND EKGINEERING CHEMISTRY
Operation Air from the laboratory line is admitted before the 100 nil. of thinner are poured into the funnel. The air lift is regulated, conveniently with the aid of a constant-pressure by-pass, to supply a smooth, equally distributed flow of bubbles. After the first three quarters of the thinner have evaporated it may be necessary to increase the air slightly, owing to loss of liquid head. When the 50-ml., 25-ml., etc., marks have been reached, a few milliliters are run out into a small beaker and 1 ml. is pipetted into a test tube which is corked tightly. The remainder is poured back into the funnel at once. Aniline points, using equal volumes of thinner sample and anhydrous aniline, were taken at the end of each run and read to 8.1"C. with the same thermometer.
Fractional Solvencies Table I1 lists solvencies of fractions remaining from the evaporation of two typical mineral spirits, and of several
VOL. 11, NO. 8
blends of these with commercial high-solvency naphthas. The solvency corresponding to an aniline point of about 32" C. was taken as typical of that of the total thinner present in many current industrial oleoresinous finishes. Figure 3 illustrates the changes in solvencies. Table I11 shows pertinent inspections of the commercial thinners used.
Literature Cited (1) Bent, F. A, and Wik, 5.N., IND.ENG.CHEW,28, 312 (1936). (2) Bogin, C., and Wampner, H. L., Ibid., 29, 1012 (1937). (3) Dorsch, J. B., and Stewart, J. K., Ibid., 30, 325 (1938). (4) Lowell, J. H., Ibid., Anal. Ed., 7, 278 (1935). (5) MoArdle, E. H., Moore, J. C., Terrell, H. D., Haines, E. C., et al., Ibid., 11, 248 (1939). (6) Metzinger, E. F., Paint, Oil Chem. Reu., 99, No. IO, 9 (May, 1937). (7) Rubek, D. D., and Dahl, D.W., I N D . ENG.CHEM.,Anal, Ed., 6, 421 (1934). (8) Stewart, J. K., Dorsch, J. B., and Hopper, C. B., IND. Exc. CHEM.,29, 899 (1937).
A New Style of Chemical Heater W. MASTER, Consolidated Edison Company New York, Inc., Brooklyn, N. Y.
A
of
KEW style of electric heater, developed several years ago by the Research Bureau of the Consolidated Edisoii
Company, has proved very satisfactory in severe chemical laboratory service. It may be used as an ordinary hot plate or as an "air bath" when provided with a removable heat-reflecting jacket. In the latter form, shown in the photograph,
it is a n excellent substitute for water, oil, or glycerol baths with the added advantage of eliminating liquids. Under ordinary conditions the air-bath temperature may be maintained within a few degrees by means of a rheostat, transformer, or thermostat. I n a draft-free location or by the use of a double jacket, regulation within a fraction of a degree is possible. It is exceptionally rugged and to date no trouble has been experienced from corrosion so frequently encountered in chemical heaters. Various sizes may be made using stock heating units. The diagram shows the construction of a good general-purpose heater built around a 500-watt Chromalox A-20 ring unit. This type of unit is inherently resistant to corrosion and is further protected from spilled chemicals by the lip around the bottom of the casting and the transite clamping plate which holds it in intimate contact with the casting. Prongs of nickel silver are substituted for the wire-holding nuts on the unit, care being taken not to disturb the nuts next to the sheath. The holding rod is 18-8 stainless steel 0.5 inch in diameter and the jacket is anodized 25 aluminum alloy tubing of 4-inch diameter.
