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animals commenced to lose weight and gave other evidence that their body reserve of vitamin A was exhausted, their diet was supplemented by uniform daily additions of cod-liver oil. As in other studies of this character, the experimental period was 45 days, a t the end of which the test was concluded regardless of whether the animal was gaining or failing. The amount of oil administered, the amount of food ingested during 5-day periods, and the change in body weight are reported in the charts. Nine animals were used to test the vitamin potency of Oil 8. Of these, four which received less than 5 mg. a day were unable to recover from their malnutrition. The five animals that received 7.88 mg. or more of the oil daily recovered from the effects of their previous vitamin-deficient diet. From these data it appears that about 8 mg. of this oil are required to supply sufficient vitamin A to meet the needs of an albino rat for growth. None of the eight animals that were fed 3.32 mg. or less of Oil 9 were able to recover from the vitamin A privation to which they had been subjected. Considering the results of the series as a whole, one would conclude that between 7 and 14 mg. of this oil would be required daily to produce good growth in this type of laboratory animal. According to the limited results obtained concerning the
Vol. 16, No. 11
vitamin A potency of Oil 10, 3.36 mg. of this oil daily supplied sufficient vitamin A to produce fairly good growth in albino rats. The tests of Oil 26, which was distributed by the same concern, show it to be a more potent oil. Inasmuch as nine animals received amounts of Oil 11 varying from 0.9 to 14.5 mg. daily, and all failed to recover from the malnutrition occasioned by an inadequate supply of vitamin A, it is concluded that more than 14.5 mg. of this oil are needed to meet the vitamin A requirements of the laboratory animals. The charts which report the results of the tests of Oils 27, 37,43,44, and 80, show a quite distinct line of demarcation between those animals that recovered from malnutrition induced by an inadequate supply of vitamin A and those that did not recover. It will also be noted that the amount of the different oils required to effect recovery of the laboratory animals is not identical for the different oils. Accordingly, it is evident that the vitamin content of these oils varies appreciably. I n brief, the tests reported here show that the medicinal cod-liver oils on the market are not uniform in vitamin content, and that if one wishes to be assured of a cod-liver oil of high vitamin potency, it is essential to insist on an oil whose vitamin potency has been determined.
Quantitative Estimation of Anthracene in Anthraquinone' By Harry F. Lewis CORNELL COLLEGE,MT.VERNON.IA.
HE estimation of small amounts of anthracene in anthraquinone is of interest in connection with the use of the anthraquinone in sulfonation. This value can be obtained by analyzing the sample for anthraquinone, then oxidizing a fresh sample, using the Luck method, and estimating the total anthraquinone after oxidation. By subtracting the first value from the second, the amount of anthraquinone formed from the anthracene present may be determined. This procedure is long and tedious, and gives unsatisfactory results. Among the properties of anthraquinone described in the literature may be found the fact that pure anthraquinone dissolves in oleum, producing a yellow color which does not change upon heating the oleum. This is in contrast with the behavior of anthracene, which chars rapidly in hot oleum with the evolution of sulfur dioxide. These facts form the basis of a qualitative test for the purity of anthraquinone as devised by Nelson and Scott. They found that the color of the filtrate obtained after diluting the hot oleum mixture could be used in determining whether a sample of anthraquinone was of satisfactory quality, comparing the color with that obtained in a similar manner with a satisfactory anthraquinone. This qualitative test has been developed into an analytical method for the quantitative estimation of small amounts of anthracene in anthraquinone. PROCEDURE
T
A 2-gram sample of anthraquinone is taken from a wellground, dry mixture of the unknown and placed in a 15.2 X 2.5-cm. (6 x 1 in.) hard-glass test tube, 25 cc. of 10 per cent oleum added, the stopper containing a thermometer and capillary vent tube inserted, and the tube heated in a bath a t 150' C. for 5 minutes. The contents of the tube are then poured into 500 CC. of distilled water, stirring meanwhile. 1
Received May 15, 1924.
Sufficient of the suspension is filtered to give a color comparison against standards made up with solutions of potassium dichromate and cobalt chloride. These can be easily made by running known mixtures of anthracene and anthraquinone under the conditions described above and matching their colors in the preparation of standards. The char solution darkens on standing and the color comparison should therefore be made immediately after filtering. ACCURACY The method as described will easily detect as small an amount of anthracene as 0.1 per cent and differentiates easily up to 7 * 0.2 per cent. This is sufficiently high, for few commercial anthraquinones have an anthracene content greater than 5 per cent, whereas purified anthraquinones have even smaller amounts.
RESULTS The best color results were obtained with 10 per cent oleum. Oleum of 15 per cent strength causes too great a charring to differentiate easily, whereas with hot concentrated sulfuric acid an how's heating is not sufficient to produce much color. Such possible impurities as carbazol, phenanthrene, phenanthraquinone, acenaphthaquinone, and fluorene in amounts up to 2 per cent have no influence on the depth of color. Acenaphthene and naphthalene both char rapidly in 10 per cent oleum, but their presence in commercial anthraquinone is extremely improbable. Naphthalene would sublime in the driers and acenaphthene would be oxidized to the quinone, which does not char. Needless to say, they would be as undesirable in the anthraquinone to be sulfonated as would anthracene itself. ACKNOWLEDGMENT The author is indebted to the National Aniline & Chemical Company for aid in carrying out this work.
November, 1924
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A New Stability Test for Nitrocellulose' By J. B. Taylor EXPERIMENTAL STATION, HERCULES POWDER Co., KENVIL,N. J,
s
The time for reaching the maximum rise varies from 45 to TABILITY tests for nitrocellulose have been based on several general methods, including the coloring of test 60 minutes, but shows little relation to the rise. The rise papers, appearance of nitrous fumes, and quantitative could be checked to 0.05'-0.10" C. To show that the temperature-rise test depends on actual measurements of the products of decomposition. All involve decomposition, a number of tests were made on partially heating a t more or less elevated temperatures. The proposed test was planned as a substitute for the Abel purified nitrocotton. 85.5' C. test, better known as the K I test. This heat test, TABLE 1-TEXPERATURE-RISE TESTON PARTIALLY PURIFIED NITROCOTTON while of long standing, is now generally recognized as unreliT-R TREATMENT c. able in judging true stability. It has been said to indicate After beating 2.80 After a 6-hour boil the beginning of decomposition, but there are a number of 1.70 After a 2-hour boil 1.40 substances which may mask any action of this kind. It is es1.13 After four 1-hoitr boils sentially a trace test, showing the Dresence of minute auantiTable I shows a typical series. The sample was a nitroties of impurities which usually have no cotton of 13.5 per cent nitrogen. The first sample was taken bearing on real stability. The temperature-rise test, as the new after the beating treatment, the first step in the final purificatest has been called, depends on a meas- tion process. The decrease in rise indicates that the method urement of the heat evolved on decomposi- is sharply affected by the extent of purification, and follows tion. It was suggested by the old Wal- closely actual stability changes. Typical results on finished nitrocottons are given in Table tham Abbey silver vessel test for cordite. .II. The samples are all nitrocottons intended for use in the Here the ground powder was heated a t 80" C. in vacuum flasks containing thermom- manufacture of smokeless powders. eters. The test lasted from 200 to 600 TABLE 11-TEMPERATURE-RISE TESTON FINISHEDNITROCOTTONS Nitrogen T-R KI hours, and ended when a rise of 2 deSample Per cent c. Min . grees had been recorded. The present 1 13.12 0.95 10 2 13.13 0.88 27 test is run a t a higher temperature, 135" 13.15 0.91 20 3 C., in order to secure a more serviceable 13.45 0.92 30 4 5 12.81 0.87 30 routine test and also to obtain increased 6 12.20 0.74 40 1 2 . 1 9 7 0 . 8 0 If3 distinction between types of nitrocotton. 12.85 S
,
1
EXPERIMEKTAL
The nitrocotton was dried a t 40' C. for 5 hours to insure uniformity in different samples. Four and five-tenths grams of the dried cotton were then placed in a FIG. NIT APPARATUS glass test tube and tamped down around POR TEMPERATUREthe bulb of a thermometer. The test r NITRO- tubes were heavy-walled, 30-em. tubes RISET ~ s FOR CELLIILOSR with an inside diameter of 1.4 em. The thermometers were long-stemmed and graduated from 130 ' t o 140" C. in tenths. This simple apparatus (Fig. 1) was adopted in place of the many other possible refinements, because it seemed to provide a quick and sufficiently accurate method of determining the feasibility of the test The tubes were placed in wells of a xylzne-toluene vapor bath a t 135" C. Temperature readings were made at minute intervak until the maximum temperature was reached and for some time thereafter. This maximum temperature was recorded as the temperature-rise (T-R) test value of the nitrocotton. Fig. 2 shows the variation of temperature rise with time. Bath temperature, 135' C., is reached in about 30 minutes, and then a period of slow temperature rise follows. Rapid decomposition then sets in, as shown by the first break in the slope of the curve. The temperature reaches a maximum and then decreases to an almost constant level as the decomposition rate falls off and is balanced by heat losses to the bath. 1 Presented before the Division of Cellulose Chemistry at the f37th Meeting of the American Chemical Society, Washington, D. C . , April 21 to 26, 1924.
9 10
12.14 13.50
1.03 1.33 1.20
23 24 20
From study of a variety of nitrocottons, a maximum rise of 1.10' C. under the conditions of the test appears to be the limit for a sufficiently stable nitrocotton.
T/M€ (M/NS.) FIG.2-EXAMPLB O F TEMPERATURE-TIME CURVES
It will be noticed that there is no relation between KI and T-R values. Sample 1, hopelessly unstable by the K I test, gave a passing temperature rise. This is also true of Sample 7. Sample 9, on the other hand, gave a very high T-R, but is fairly stable if judged by KI. It can also be seen that the T-R is roughly governed by the nitrogen content of the cotton. Preliminary investigations of a test depending on a temperature rise were made by 0. A. Pickett of this laboratory. The time of beginning of rapid decomposition was chosen as
