I N D U S T R 1A L A N D E N G I N E E R I S G C H E M I S T R Y
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foaming index increases. There appears to be an alkalinity optimum for minimum foaming of caseins which have an inherent tendency to foam. It might be 1%-orthwhile to investigate the effect of alkalinity more in detail, were it not that there are other and less critical means of avoiding foaming. ADDEDSUBSTANCES OTHER THBK ALKALIES. Foaming indices were measured on a number of slips that were normal, except that surface tension depressants or substances native to milk had been added. Data are given in Table IT’. The addition of normal constituents of milk t o a slip containing a nonfoaming casein did not cause foaming. Addition of 2 per cent of butter oil to the formula of a slip containing a foam-producing casein decreased the foaming somen-hat. This does not contradict the statement made in a previous paper ( 3 ) that as much as 3 per cent fat in casein may not affect foaming tendency, since added fat is dispersed much less finely than fat in the casein itself, and its effect Yould be expected to differ from that of intimately mixed fat. TABLEIv. FOAhfISG STANCES CASEIN
INDEX AS AFFECTEDBY OTHERTHAN ALKALIES
S U B S T A N C E A D D E D PER
11.0 GRAMSCASEIN
ADDED SUBFOAMIXQ INDEX
Grams
A A
;-41“ A A
i
A B B B B
{ Conc. CaH;(POa)t 2Hz0 NHIOH KC1 Butter oil Phospholipid Soap Ca(OH)z Ca(OH)z Ca(0H)z Lactalbumin
Butter oil
Isobutyl alcohol Octyl alcohol
0.0 0.0
o:i2 3 . 0 ml. 0.22 0.22 0.22 0.30 0.20 0.50 1.00 1.00
0.8 0.0 0.3 0.4 0.2
1.8 0.0 0.5 29.0 21.5 0.0 0.0
o:i2 2 . 0 nil. 2 . 0 ml.
Vol. 25, No. 11
APPLICATION OF T’ACCCM TO SLIPS. In the belief that removal of entrapped air from slips might lessen ability to foam, vacuum was applied to a slip for an hour before testing. The index was lowered from 29.0 to 24.7, a change of no practical significance. DISCUSSIONOF RESULTS The theory which these results suggest to the authors is that the foaming tendency of casein is dependent on the degree of aggregation of the casein molecules in the curd. This degree of aggregation is assumed t o be to some extent conditioned during secretion of the milk. The cohesional forces involved are apparently not affected by the dispersional effects of homogenization or of dilution, but are evidently extremely sensitive to conditions a t the moment of precipitation of the casein. Causes of fine curd are causes of foaming. Rapid agitation a t the time of precipitation seems t o prevent sufficient cohesion of molecules to give the desirable aggregation; higher temperatures appear t o increase the forces of cohesion, or “stickiness,” between molecules and thus aid in the aggregation process. The desirable size for these aggregates appears t o be less than that of even the finer grains of dry commercial casein and the cohesional forces involved are not identical with those which hold the aggregates together in the dry grains. Aggregates of the nonfoaming (larger) sort are much more potent in establishing the foaming characteristics of a mixture than are those of the sort (smaller) which, alone, cause foaming. It is realized that this theory is neither complete nor unassailable; it is presented in an effort to correlate the results on some single basis. LITERATURE CITED (1) Richards, C . W., and McFail, L. W., Paper Trade J.,97,NO.1, 29 11933).
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When surface tension depressants were added to the formula in quantities which seemed t o the authors t o be impractically large for commercial use, the inherent foaming tendency of a casein was overcome completely. Since information regarding the proportions and method of use of antifoaming agents in the coating industry is not readily available, it was decided to do no work with these substances beyond verifying the fact of their effectiveness.
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I
(2) Sutermeister, E., “Casein and Its Industrial Applications,” p. 134, Chemical Catalog, 1927. (3) Whittier, E. O., Gould, S. P., Bell, R. W.,Shaw, M . B., and Bickinu, G. W., IXD.ENG.CHEM.,25, 904 (1933). (4) Williams,H. E., Ihzd., 18, 361 (1926).
RECEIVED M a y 24, 1933. Some of t h e information in this paper was presented a t a conference on paper-coating casein at Kashington, D. C., January 13, 1933, and a t a meeting of t h e Technical Association of the Pulp and Paper Industry a t New York, February 13 t o 16, 1933.
Laboratory Drain-Tray JOHNL. WILSON,Economics Laboratory, Inc., Saint Paul, Minn.
L
ABORATORIES are frequently equipped with only small and unhandy sinks. Many times there are washing or other operations which one wishes t o carry out over some safe drainage area, but which cannot be performed conveniently even in the larger sinks, Occasionally, in spite of the
SKETCH OF DHAIN-TR~Y utmost care during experiments, accidents occur, flooding the laboratory table with water or other liquids which run off the edge and drip down over the drawers to the floor. Time and
nervous energy are then wasted in cleaning up the mess. Such experiences led the author, after a search of catalogs of apparatus makers and of the literature failed to reveal a suitable apparatus, to design the simple drain-tray or drain-pan shown in the sketch. The tray, first made more than a year ago, has proved to be a very convenient and much used piece of laboratory equipment. Since the tray is not attached to the table top, it may be moved about as desired, or removed entirely and set in place again easily when needed. Pans of various sizes may be made to fit the requirements of use. The first tray was made of galvanized sheet iron. Another was made of acidproof baked enamelware. Trays of enameled metal should have the outlet lip curled back under, as shown in the figure in order to bring the edge of tlie lip, which does not take enamel as well as flatter portions, up high enough to keep it free from the action of the draining liquids. RECEIVED September 23, 1933.
