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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 7, No, 1
to show some peeling with corrosion of a plane before it is placed in actual serthe metal after one season in the accelervice. An average of a month's drying ated test; green synthetic resin enamel time was also allowed after applying the showed similar results. In a general way, final coat of paint to the test specimens it can be said that exposure for one season before s t a r t i n g t h e test; from 1 to 2 in the accelerated test is equivalent to 3 weeks' drying time was allowed between years or more of exposure under the atcoats, In tests of this kind it would be mospheric conditions prevailing a t Kern desirable to investigate varying drying Kensington. Coatings mliich last longer periods, in order to establish the mini$ than one season in this test would he mum drying time allowable. expected to possess very long life under It is difficult to state what one season land service conditions. in the accelerated test means in years of service, because service conditions vary !I.CKSOWLEDG~IEST so widely. However, cornparatiye tests have been made with many of the coatThe original design and as5embly of the test a p p a r a t u s d e s c r i b e d in this ings, both in air exposure and in the acFIGURE8. TEST Box OF 17s-T celerated test described. For example, AFTER sEl\soss, Expaper were w o r k e d out in 1923 by POSCRE members of t h e T e c h n i c a l Direction two coats of a l u m i n u m p a i n t m a d e Treated ,,ith phosphoric acid Bureau of A l u m i n u m C o m p a n y of with an 80-gallon ester gum spar varnish, which showed failure on 1%-T in one followed by synthetic reein-base zinc' America, especially E. Blough, C. F. (5 montlls) in the accelerated test, chromate resin-base primer,aluminum iollolved by paint. synthetic Nagel, Jr., and F. V. Hartman, with the assistance of the engineering staff of the have shown o n l y b e g i n n i n g f a i l u r e after 3 years of normal atmospheric exposure on panels ex- Glenn L. Martin Company. posed at an angle of 4.5" facing Eouth. In another case, an LITERATURE CITED oil-base iron oxide primer followed by one coat of aluminum paint had begun t o show failure in 2 season5 in the ac- ( 1 ) Edwards, J. D., and n'ray, R. I., ISD. ESG.CHEM.,25, 23 (1933). (2) Whitmore \I R. fbid. 23 19 (1933). celerated test, whereas a similar coating exposed to normal (3) R. i, kan,;\ R.,Ibid., 25, 842 (1933), air conditions was still intact after 3 years' exposure. The September 19, 1831. Presented before the Division Paint green pyroxylin lacquer preyiously nlentionedi which vxs and Varnish hell lie try a t the 88th >feetine; of the American Chemical still intact after 3 years' atmospheric exposure, had begun Society. Cleveland, Ohio, September i o t o 14. 1934.
and
A Rapid Method for Dialyzing Large Quantities of Protein Solution GILBERT C. H. STONE, College of the City of New York, New York, N. Y.
D
URING the course of preparing large quantities of pure a good-sized paddle. The solution may be preserved with proteins, it was found necessary to dialyze batches of 5 toluene, chloroform, or thymol, the rapid evaporation of which to 10 liters of the colloidal ampholytic solutions. The simple is prevented by covering the crock with a large piece of cardapparatus herein described was designed to carry out the board perforated by the necessary holes. Because of the continual motion of dittlyzing process efficiently. the solution and t h e c o n s t a n t flow Figure 1 shows a c o n t a i n e r of a n d r e m o v a l of t h e dialysate, the capacity sufficiently g r e a t t o hold t h e p r o t e i n s o l u t i o n . P i e c e s of motor Srlrver process is rapid. Tubular Cellophane is easily obtained, and when wet is 5-cm. (2-inch) tubular Cellophane, of a b o u t 25-cm. (10-inch) length, are very strong. Breakage of the sacs, due to internal pressure such as may folded a t one end and clamped closed occur in the usual methods of dialysis by means of screw c l a m p s , fitted where the medium to be dialyzed is with two-hole r u b b e r stoppers and Water placed within the sac, is eliminated, bent glass tubes, and connected in because in this case the mater passes series. They are placed in the proout of the bags into the solution. tein solution in the crock, and cold tap water is run through them. The It was found that 10 liters of a soluweight of the screw clamp is sufficient tion consisting of a protein dissolved to k e e p t h e water-filled bags subin 10 per cent ammonium sulfate could merged in the solution. After most Crock be f r e e d f r o m t h e s a l t , as far as of the electrolytes have been removed possible by ordinary dialysis, in the from the p r o t e i n s o l u t i o n , a slow a b o v e a p p a r a t u s in 24 hours-18 s t r e a m of d i s t i l l e d w a t e r is run with tap water and G with distilled through the bags instead of the tap water. water. The author is indebted t o C. A. The solution in the crock is kept Marlies for helpful suggestions. in motion by means of a slow-moving stirrer, motor-operated, and fitted with FIGURE1 RECRIIVDOctober 4, 1934.
