Aug., 1919
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING. C H E M I S T R Y
flected in all computations based thereon-as in the calculation of percentages-and is so indicated. With the exception of Expts. 3 and 4, the period of reduction in all the experiments was uniform, consisting of a hr. treatment under reflux on the wire gauze and I hr. on the steam bath. I n t h e exceptions noted, the reflux period was doubled, thus making the entire digestion cover 2 instead of I hrs. While no material advantage in the longer treatment is observable there can be no objection thereto. A brief survey of the results presented will suffice t o show the efficacy of the method.
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has nearly or quite ceased. Toward the latter part of this operation, render the liquid about neutral with a few drops of acetic acid in order t o further reduction. Transfer the contents of the flask t o a separatory funnel, preferably of the Squibb type, withdrawing and washing the mercury in a second separatory funnel with a t least two 5 0 cc. portions of water. Pass the several aqueous solutions quantitatively through a small filter, collecting t h e clear filtrate in a suitable beaker. Precipitate with silver nitrate after the addition of about 5 cc. of nitric acid, and proceed with the determination of the resulting silver bromide in the usual gravimetric way, employing, if available, a Gooch crucible in the operation of filtering. The weight of the silver bromide multiplied by the factor 1 . 2 3 will give the quantity of monobromated camphor originally present in the sample taken for analysis. A control should be run on the amalgam in order t o determine whether any correction is necessary for the presence of halogen in material quantity.
METHOD
Ascertain t h e weight of 2 0 or more tablets, reduce t o a fine powder and keep in a small tube or specimen bottle provided with a tightly fitting cork or glass stopper. On a metal or glass scoop weigh out a n amount of the sample equivalent t o not less than I O O or more t h a n 2 0 0 mg. of the camphor derivative alleged t o be present. Transfer quantitatively with 2 0 cc. of 96 per cent alcohol and I O cc. of water, t o a small (100 cc.) round-bottomed flask, containing 1 5 g. of I per cent sodium amalgam. Connect the flask, by means of a rubber stopper, with a short vertical reflux, preferably of the Allihn or of the worm type. Heat the mixture over a wire gauze just enough t o cause t h e liquid t o boil gently for a period of not less t h a n 3 0 min. After cooling slightly, wash out the condenser tube first with 5 cc. of alcohol, then with 5 cc. of water, receiving the washings in the flask below. Remove t h e flask t o the steam bath, heating for another hour, or until the evolution of hydrogen
SUMMARY
This method for the estimation of monobromated camphor in migraine tablets takes advantage of the fact that, when an aqueous-alcoholic solution of the camphor derivative, either alone or in admixture with other substances, is subjected t o the action of sodium amalgam on heating, among other changes the bromine is split off quantitatively in t h e form of its sodium salt, which may then be determined gravimetrically in the usual way. SYNTHETIC PRODUCTS LABORATORY BUREAUOF CHEMISTRY,DEPARTMENT O F AGRICULTURE WASHINGTON, D. C .
LABORATORY AND PLANT ~~
ACID TEST O N ENAMEL WARE By W. D. COLLINS
Received February 8, 1919
The testing of enameled steel ware and of enamels for coai;ing sheet steel has been discussed by Orton,’ J. B. Shaw,2 L a n d r ~ m , ~P ~ s t e , and ~ Frost5 in papers presented a t meetings of the American Ceramic ”Society. and published in the Transactions of the Society. Much of the work of these authors was with special test pieces or vessels and the results of acid tests reported were largely based on loss of weight of the test pieces, or changes in appearance. A recent article by Miller6 gives the amounts of antimony dissolved from certain enameled vessels by treatment with different agents. One gray sauce pan lost 26 mg. of antimony when 1500 cc. of 4 per 1 “Testing of Enameled Sheet Steel Wares,” Trans. Am. Ceram. Soc., 11 (1909), 320-41. * “Testing Sheet Steel Enamels,” Ibid., 1% (1910), 463-93. 9 “Resistance of Sheet Steel Enamels t o Acetic Acid,” Ibid., 13 (1911), 494-501; “Comparison of Ten White Enamels for Sheet Steel.” I b i d , 14 (1912), 489-509. 4 “The Relative Action of Acids on Enamel,” I b i d . , 17 (1915), 137; I b z d , 18 (1916), 762. 6‘‘The Action of Acetic Acid Solutions of Different Strengths on a Sheet Steel Enamel,” J . Am. Ceram. Soc., 1 (1918), 422-8. 5 “Solution of Antimony from Enameled Cooking Utensils,” J. Home Econ., 8 (1916), 361-7.
cent acetic acid was boiled in the vessel for l / 2 hr. Food substances, grape juice, cider, cranberry pulp, spinach, and sweet milk, when cooked in the same vessel, dissolved proportions1 amounts of antimony. The results indicate t h a t for the solution of antimony from enamel ware 4 per cent acetic acid may be considered fairly representative of a number of food products which will dissolve antimony from such vessels. The test by boiling with 4 per cent acetic acid is comparatively old. Koerner’ refers t o a regulation of the German government, dated June 25, 1897, t h a t vessels for cooking shall not give up any lead when 4 per cent acetic acid is boiled for l/z hr. in the vessel. The results reported in Table I were obtained during the examination of a number of enameled dishes t o learn the extent of the use of antimony oxide as a substitute for tin oxide in white enameled ware, and in connection with a few tests of different wares as t o their acid resistance. Altogether, tests were made on 3 2 samples of white ware from 21 manufacturers, 1 5 samples of gray ware from 9 manufacturers, 1 2 samples of blue ware from 4 manufacturers, and 2 1 “Bleihaltige, im Sinne des Gesetzes ungiftige Glasuren,” Sprechsaal, 39 (1906), 2-4.
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miscellaneous samples. As ware of more than one kind was tested from some manufacturers, the total number of establishments represented was only 2 6 . A number of the samples were purchased on the open market, some were obtained from the General Supply Division, Quartermaster Corps, of the Army, and a few were received from manufacturers. The samples were treated with different acids of various strengths. The effect on t h e appearance of the surface, and the amounts of total material, of silica, of antimony, and of lead dissolved were determined for different samples. APPEARANCE
I n most of the tests the appearance of the vessels after the action of the acid was noted. Boiling 4 per cent acetic acid for 30 min. was the test used in the greatest number of cases. One per cent citric and tartaric acids were used in some tests. They had approximately the same effect on the glaze as 4 per cent acetic acid. A number of tests were made with I and 2 per cent acetic acid. I n some of the tests the vessel with the acid was heated on the steam bath for 30 min., or for a longer time. LOSSof glaze and deterioration in appearance cannot be expressed numerically with ease. Therefore all the observations have been summarized under the headings good, fair, and bad. When no effect on the glaze could be detected, or a t most only a slight attack a t the level of the surface of the liquid, the appearance was called ((good.” When the glaze had entirely disappeared where the liquid touched it, and the surface was left rough, the appearance was called ‘(bad.” Those neither “good” nor “bad” were called “fair.” The results are summarized in the following table: TABLE I-APPEARANCEOF SURFACE AFTER TREATMENT WITH BOILING AWTICACID FOR 30 MIN. Strength of Acid Per Cent Good’ Fair 4 13 13 4 8 8 4 1 3 2 1 3 1 2 3
...... ........
White ware... Gray ware., Blue ware.. Blue ware.. Blue ware..
........ ........ ........
1
Bad 4
2 2
2 5
Total 30 18 6 6
10
Figures in this and following columns give the number of samples.
The loss of glaze detracted most from the appearance of the blue ware. The glass seemed t o dissolve leaving t h e clay or other infusible constituents showing a t the surface. Although some clay could be scoured off, the ware did not recover its original color. With white ware the only loss was the glaze. I n nearly all cases a smooth, dull surface was left after the clay was washed away, and the appearance of the vessel was like new except for the glaze. The effect on the gray ware was intermediate between the other two. The white and gray wares were not affected a t all by treatment with I or 2 per cent acetic acid which attacked severely all but two of the samples of blue ware. SOLUBILITY
A number of vessels were treated with 2 0 0 cc. of 4 per cent acetic acid on the steam bath for six or more hours. The acid solution was evaporated t o dryness
Vol.
11,
No. 8
in platinum and the residue heated approximately to constant weight in a n oven a t 1 1 0 ’ . The weight of material dissolved was determined for only 1 1 dishes-6 white, 4 gray, and one blue. The white and gray ware, of brands which are generally understood t o give good service in use, lost from 0 . 0 5 t o 0.08 g. when treated for 6 hrs. with 4 per cent acetic acid Other samples of white and gray ware lost from 0.2 t o 0 . 5 g. under similar conditions. The single sample of blue ware tested lost from 0.6 t o 1 . 2 g. On account of the difficulty of making strictly comparable tests, and the small value of the results when obtained, the subject was not pursued further. As would be expected, the amounts of material dissolved correspofided t o the loss of glaze. SILICA
Silica was determined in the material dissolved from 4 white dishes, 3 gray ones, and one blue bowl. The determination was made by adding hydrochloric acid, evaporating t o dryness, taking up the residue in hydrochloric acid, filtering, igniting, and determining the loss of the ignited residue on treatment with hydrofluoric acid. The highest percentage of silica (about 30 per cent) was obtained from a special white cup made without tin oxide. Other commercial white and gray wares had from 7 t o 2 0 per cent of silica in the dissolved material. The single blue bowl had only from 2 t o 6 per cent of silica in the material dissolved in successive treatments. ANTIMONY
Antimony was dissolved from the vessel in most cases by boiling j oo cc. of 4 per cent acetic acid for hr. and also by boiling 500 or 400 cc. of one per cent tartaric acid for l/z hr. A few results were obtained with one per cent citric acid, which dissolved about the same quantity of antimony as did the one per cent tartaric. From the solutions antimony was precipitated by hydrogen sulfide. The precipitate of antimony sulfide was dissolved in boiling concentrated hydrochloric acid. The solution was filtered, and after dilution and the addition of starch indicator, iodine solution was added t o oxidize any reduced tin. The solution was made alkaline with sodium carbonate, tartaric acid was added t o acidity, and then sodium bicarbonate until the solution was distinctly alkaline and contained an excess of sodium bicarbonate. T h e antimony was then titrated with iodine solution. I n most cases the strength of the iodine solution was such t h a t I cc. represented 0 . 6 0 6 mg. of antimony The tartaric acid dissolved two or three times as much antimony as the acetic acid. For comparison the results were averaged and tabulated according t o the number of samples losing different amounts of antimony. The j I samples examined represented the products of 2 5 manufacturers. The 17 samples with no antimony came from g manufacturers. Three of these furnished only one sample each, which was white ware One blue sample without antimony was from a manu-
T H E J O C R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
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facturer whose white sample gave up about I mg. of antimony. Another blue sample was from a company which furnished white ware without and gray ware wlth antimony. Four samples from one company, I.blue, I white, and 2 gray, failed t o give any test for,antimony. TABLE II-NUMBER
OF SAMPLES LOSING DIFFERENT AMOUNTS O B ANTISOLUTIONS OF ACETICAND TARTARIC ACIDS None 0.5 mg. 1.0 mg. 2.0 mg. Total White ware.. , . . 9 6 12 5 32 Gray ware.. 4 3 5 3 15 Blue ware , 4 0 0 0 4
MoiiIy
TO
. . . . .. .
..... ....... .... .. . ....
In general, as much antimony was dissolved from gray ware as from white. A white-coated cup which was made without tin oxide for use in these studies gave up less antimony than a number of the other white and gray vessels. The highest three values were obtained from gray vessels. The results show t h a t enamel ware can be bought, in white and gray, which is free from antimony. LEAD
Lead was dissolved from the ware of only one manufacturer. Vessels treated with different amounts of acetic acid gave up from 2 t o 9 mg. of lead. The freedom from lead shows the desire of practically all manufacturers to keep their product free from such a well-known dangerous poison. E F F E C T O F T E M P E R A T U R E CHANGES
Although no effort was made t o test the resistance of the different vessels t o changes in temperature, a number of the samples failed to hold their coating during the tests. Most of the tests with boiling acetic acid were made by placing the vessels over a Bunsen burner flame after the vessels had been filled with a cold solution of acid. I n some cases the enamel cracked as soon as the flame was applied; in a few instances large pieces of enamel chipped off a t once. I n some other cases the coating seemed t o be sound until the vessel was removed from the flame, when pieces of the enamel chipped off the inside of the vessel. I n one case a dipper was removed from the flame, and placed o n a tilt: table top a t room temperature. Large pieces of enamel came off the inside a t once. I t is evident t h a t considerable differences exist in the ability of the vessels t o withstand sudden changes in temperature. Hardly any of the vessels which lost large quantities of enamel received any more harsh treatment t h a n an ordinary cooking vessel must receive. SUMMARY
Acid tests were made on 61 samples of enamel ware from 26 different American manufacturers. These included white, gray, and blue cups, bowls, and pans. The test most used was made by boiling 500 cc. of 4 per cent acetic acid in the vessel for hr. Some tests were made with I per cent tartaric acid. About half the samples of white and gray ware suffered no loss of glaze on treatment with 4 per cent acetic acid, while nearly all the blue ware was badly affected by 2 per cent acid. The amounts of material dissolved corresponded to the loss of glaze. Seventeen samples from 9 manufacturers gave no antimony. There was no great difference between
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the white and gray ware in the amounts obtained from the 34 vessels which gave from 0 . 5 t o 2 . o mg. of antimony. Lead was found in ware from only one manufact ur er . Pieces of enamel chipped off several vessels under heat treatment no more severe than might be received by any cooking vessel. BUREAUO F CHEMISTRY
u. s.DEPARTMENT O F AGRICULTURE WASHINGTON, D. C.
CHANGES IN OILS UPON STORAGE B y HENRYA. GARDNER Received March 15, 1919
I n various papers’ the writer has called attention t o the storage changes t h a t may take place in oils when ground with pigments. For instance, when paints made with pure raw linseed oil having a certain iodine number are stored for long periods of time, subsequent analysis may show t h a t the oil has a lower iodine number than t h a t called for by the specifications upon which the paints were made. Reactions t h a t are responsible for such changes are of course greatly stimulated a t high temperatures. As a result of some investigations t h a t have just been completed, it would appear t h a t similar but less marked changes may take place in pure oils without the presence of pigments, and t h a t such changes will depend t o a very great extent upon the method of storing and certain other factors. During the early part of 1911 the writer secured a quantity of a number of commercial oils for use in experimental paints t h a t were t o be exposed t o the weather t o determine the efficiency of various oil mixtures as paint ingredients. After the painting tests were made, samples of the pure oils were placed in pint glass bottles having ground glass stoppers. The bottles were well filled, an air space above the oil of more t h a n one inch not being allowed in any instance. The oils were placed upon a shelf in the laboratory where they were exposed t o indirect light and t o ordinary room temperature (in the summer not over 10.5’ F., and in the winter not less than 35’ F.). I n November 1914portions of the oils were removed from the bottles and examined as a check against the original determinations. Air was, of course, admitted during this procedure. During September 1916 the oils were again examined, further quantities being removed for this purpose. The bottles were again placed upon the shelf and allowed t o remain there until March 1919,when further quantities &ere removed for examination. The results obtained on these samples are given in Table I. I n Table I1 are shown the results on a series of oils obtained during 1914 and kept under similar conditions t o those shown in Table I, the analyses being made in September 1916,and in March 1919. 1 “The Effect of Pigments upon the Constants of Linseed Oil,” J . Frank. Inst., 1912, 415-423; ”Changes Occurring in Oils and Paste Paints, Due to Autohydrolysis of the Glycerides,” I b i d . , 1914, 533-540, “A Study of Some Curious Painting Phenomena,” I b i d . , 1916, 681-695.
