T H E JOURN-4L OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
Mar., 1922
TABLEX I
taining the original and treated hydrogen peroxide solutions being exposed to white light under identical conditions. Table IX gives the result of these experiments. TABLE IX SAMPLE A
B
Bottle 1 2 With quinine sulfate. . . . . . . . . . . 1 2 3 Original.. ....... 1 2 3 With quinine sulfate. .......... 1 2 3
Original..
.......
VOLCMBSOF OXYGEN Per cent Loss Original After 11 Days in Volume 16.44 l&60 6.1 16.44 15,16 7.8 16.67
16.67 16.67 25.68
25.68 25.68
26.10 26.10 26.10
16.59 16.68 16.54 24,44 24,21 24,26
0.5 0.0 0.8 4.8 6.7 5.4
%,I4
0.0
26.21 26.18
0 :u
0.0
These results show that quinine sulfate restrains decomposition of hydrogen peroxide solutions of high strength. It was considered interesting to determine whether a solution of pure hydrogen peroxide which had been stored until considerably reduced in H202 content would show a similar result and also whether a reduced amount of quinine sulfate would be effective. This constitutes a more rigorous test of its effectiveness than when added to a fresh solution because solutions of hydrogen peroxide which have undergone decomposition are more susceptible to decomposition. These results are given in Table X. TABLE X SAMPLE 1
Description Grs. per Gal.
+
7/12
VoLuims OF OXYGEN Per cent LOSS Original After 1 6 Days in Volume 5.60 3.39 38 3
The results given in Table X show that addition of quinine sulfate restrains the decomposition of hydrogen peroxide solutions which have already lost considerable oxygen and that the restraining effect is dependent upon the amount added. Moreover, it appears that 2l/3 grains per gallon are as much as need be added for preservation. It was thought interesting to determine whether quinine sulfate added in the various amounts used in all of these experiments would cause a bitter taste in the product. Organoleptic tests made by seven observers, all of whom were asked to determine whether any of the samples had a perceptible bitter taste, gave results which established the fact that quantities up to the limit tested (31/2 grains per gallon) did not contribute any bitter taste to the original quinine-free solutions. YARIOUS PRESERVATIVES-A sample of hydrogen peroxide made by a prominent pharmaceutical manufacturer was found to contain 11.75 grains of benzoic acid, 0.93 grain of salicylic acid, and 1.28 grains of acetanilide in each gallon of the product. Tests were made to determine the effect of this mixture of substances as compared t o the same quantity of benzoic and salicylic acids without any acetanilide. I n connection with the organoleptic tests, it was found that some observers reported that plain hydrogen peroxide solutions had a slightly bitter taste. I n fact, this is a property of pure hydrogen peroxide. Addition of 1 grain of saccharin per gallon of hydrogen peroxide solution was found to improve the taste. An experiment was, therefore, made to determine the effect of a mixture of 21/3 grains of quinine sulfate and 1 grain of saccharin on the stability of hydrogen peroxide (Table XI). A mixture of benzoic acid and salicylic acid in the quantity used exerts a preservative action, which is not appreciably enhanced by the amount of acetanilide added. Quinine sulfate and saccharin in the quantities used also show a preservative action, although the results with quinine sulfate alone appear to be better.
186
SAMPLE A f 11.88 grs. benzoic acid 0 , 9 2 gr. salicylic acid 1 . 2 3 grs. acetanilide per gal. B 4- 11.88 grs. benzoic acid 0 . 9 2 gr. salicylic acid 1 . 2 3 grs. acetanilide per gal. A 4-11.95 grs. benzoic acid 0 , 9 2 gr. salicylic acid per gal. B 11.88 grs. benzoic acid 0 . 9 2 gr. salicylic acid per gal. A 2'/a grs. quinine sulfate 1 gr, saccharin per gal. B 2'/r grs. quinine sulfate 1 gr. saccharin per gal. ANo addition B hTo addition
+ + +
-
VOLUMESOF OXYGEN After 1 After 4 Original Wk. Wks.
PERCENT Loss IN VOLUME 1 Wk. 4 Wks,
16.16
15.81
13.96
2.1
13.6
25.45
24.98 21.96
1.8
13.7
16.08
15.66
13.69
2.6
14.8
2 2 . 4 5 24.98
.....
1.8
..,
15.97
13.82
0.7
14.0
26.42 24.91 21.63 16.00 14.63 10.11 26.42 23.89 16.63
2.0
14.9
8.5
36.6
6.0
34.5
16.08
.
Ordinarily, 24 grains of acetanilide are added to each gallon of hydrogen peroxide as a preservative. It has been the author's experience that 2'/3 grains of quinine sulfate to each gallon are as efficient a preservative and introduces only one-tenth the amount of foreign substance. Moreover, acetanilide causes the development of yellowish or brownish tint and unpleasant odor. The author's experiments have shown that an odor identical with iodoforni is developed in soldtions of hydrogen peroxide which contain a slight excess of acid. Quinine sulfate does not cause any foreign odor or color t o develop. As mentioned before, quinine is used in one of the most widely sold medicinal hydrogen peroxide solutions, and it certainly has advantages over acetanilide, especially in view of the fact that the law does not require its presence to be declared upon the label of the product.
Du Pont Chemical Fellowships It is interesting to note, in these days of retrenchment, that the du Pont fellowships in chemistry in twenty colleges and universities throughout the United States are to be continued for the academic year 1922-23. These fellowships were established four years ago, a t the time when the war made necessary the development of a self-contained chemical industry in this country. The fellowships are for graduate work. Recipients must be graduates devoting the major part of their time to the study of chemistry, and are selected by the university authorities, not by the Company. The plan differs from the usual one for industrial fellowships in that the research is not necessarily to be directed along some line in which the Company is interested, but the student is left free, under the direction of his instructors, to follow whatever line of investigation seems to him most promising. The institutions which receive these fellowships are: Brown University, Providence, R. I. California Institute of Technology, Pasadena, Cal. University of California, Berkeley, Cal. University of Chicago, Chicago, 111. Columbia University, New York, N. Y. Cornell University, Ithaca, N. Y. Delaware University, Newark, Del. Harvard University, Cambridge, Mass. University of Illinois, Urbana, Ill. Johns Hopkins University, Baltimore, Md. Lafayette College, Easton, Pa. Massachusetts Institute of Technology, Cambridge, Mass. University of Michigan, Ann Arbor, Mich. University of Minnesota, hlinneapolis, Minn. Ohio State University, Columbus, Ohio Princeton University, Princeton, N. J. University of Virginia, University, Va. University of Washington, Seattle, Wash. University of Wisconsin, Madison, Wis. Yale University, New Haven, Conn.
