March, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
stantid percentages of water and the effect on the lead number was not so marked as in the case of the writers’ experiments, in which five of the menstruums contained only a very small proportion of water. The two methods for vanillin agree very well, the largest differences being 0.03 and 0.04 per cent in extracts from Mexican beans and Bourbon beans, respectively, which were made with ether. After the ether solution of vanillin had been washed with 2 per cent ammonia and evaporated, some residuc, which was weighed and reported as coumarin, remained. This residue, which had no odor of coumarin and was slightly colored in most cases, was probably a resinous material. The largest quantities were found in Tahiti bean extracts. Of the residues obtained in the analyses of the Tonka extracts, reported under the heading “vanillin,” the highest (0.10 per cent) was found in the extract made with 65 per cent alcohol. These residues likewise had no odor of vanillin and gave no test with ferric chloride. The extractive matter soluble in 65 per cent alcohol, reported in Table 11, Part I, was determined by evaporating a measured quantity of the extract in a vacuum oven after mixing with sand. It was thought that less vanillin would be lost by this procedure than by the official method for the determination of total solids in vanilla extract. However, when 10 cc. of a standard vanillin solution containing 20 mg. of vanillin dissolved in 65 per cent alcohol (by volume) were evaporated in the vacuum oven under the same conditions, a residue of only 1.2 mg. remained, showing that nearly all the vanillin had been volatilized. An experiment was conducted to determine whether losses of vanillin occurred when the several solvents were removed under diminished pressure. Quantities of vanillin were dissolved in 95 per cent ethyl alcohol, 91 per cent isopropyl alcohol, U. S. P. ether, U. S. P. acetone, 99.5 per cent carbon tetrachloride, and 95 per cent ethyl alcohol containing vanilla resins. I n the case of each of these solutions 100 cc. were measured into double-necked distilling flasks and the solvents were removed a t 7 0 mm. ~ pressure. When dry, the vanillin remaining in the flasks was dissolved in 95 per cent alcohol and diluted to 100 cc. (Solutions a, b, c, d , e, f). Fifty cubic centimetew of the solution of vanillin in carbon tetrachloride and of the solution of vanillin in ether were allowed to evaporate spontaneously to dryness, and the residue was dissolved in 95 per cent alcohol and diluted to 50 cc. (Solutions g and h). The original solutions of vanillin in those solvents that are miscible with water (ethyl alcohol, isopropyl alcohol, acetone, and tha ethyl alcohol containing vanilla resins) and Solutions a, b, c, d, e, f, g, and h were treated as follows: Five cubic centimeters of solution were added to several hundred cubic centimeters of distilled water in a volumetric flask of 500 cc. capacity. Enough distilled water to make 500 cc. was added and the solution was thoroughly mixed. Five cubic centimeters of each solution were then withdrawn into a 50-cc. volumetric flask, 5 cc. of sodium tungstate-phosphomolybdate reagent were added, and after 10 minutes the volume was made up to 50 cc. with a saturated solution of sodium carbonate. After the precipitate had been allowed to settle for half an hour, the solutions were filtered through dry filters.
A comparison between the original solutions and those from which the solvent had been removed under diminished pressure was made in a Duboscq colorimeter. The percentages of vanillin recovered were as follows: from 95 per cent ethyl alcohol, 99.9 (duplicate 98.2); from 91 per cent isopropyl alcohol, 98; from U. S. P. ether, 99; from U. S.P. acetone, 98.3; from 99.5 per cent carbon tetrachloride, 95.6; and from the alcohol containing vanilla resins, 98.5 (duplicate, 98.5). Since these recoveries are practically complete except in the case of carbon tetrachloride, it is probabie that the dif-
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ferences in the vanillin contents of the various extracts are due to the action of the solvent in question rather than t o any loss sustained in its removal. When making up the solutions the weighed amount (3 grams) of vanillin was dissolved in about 160 cc. of the solvent. The entire amount dissolved except in the case of carbon tetrachloride. The undissolved portion was Htered off before measuring out the quantity used in the experiment, after which 50 cc. of the solution were allowed to evaporate spontaneously, final drying being accomplished by leaving the vanillin in a sulfuric acid desiccator for 72 hours. The residue remaining (0.780 gram) showed a solubility of 1.56 grams of vanillin in 100 cc. of carbon tetrachloride. This low solubility probably accounts for the small quantity of vanillin in extracts made with carbon tetrachloride as solvent. The investigation is being continued to determine the relative values of the extracts from the standpoint of aroma and flavor, and also to determine whether or not a substantial advantage can be obtained by a preliminary extraction of the beans with carbon tetrachloride, followed by a second extraction with dilute ethyl alcohol. The data so far obtained indicate that this procedure will result in the production of a high-grade extract by the use of a smaller quantity of ethyl alcohol than is ordinarily employed.
All-Glass Apparatus for Automatic Evaporation of Water Samples’ By G . A. de Grad PUBLIC SERVIC ELECTRIC ~ Co.,IRVINGTON, N. J.
HE apparatus shown in the accompanying figures has been T found quite satisfactory for the evaporation of large samples of water in small dishes, without attention.
I
I d
FIO.2
The part A , Fig. 1, is ground to fit the neck of an ordinary volumetric flask. The flask is filled to the mark, the stopper inserted, and the flask inverted over the dish with the stopcock C closed. The stopcock is opened cautiously and the adjustment of height so made that the point I , which determines the level of water in the dish, is at a suitable height. The stopcock is then opened wide. At the close of the evaporation the lower part of the tube is washed carefully with a small amount of distilled water. I n the absence of steam an electric hot plate has been used for heating a water bath provided with the usual automatic level and overflow device. Stoppage of the water has resulted in loss of samples when left evaporating over night. This has been avoided by use of an aspirator bottle (Fig. 2 ) with the level in the bath determined by the position of the lower end of the open tube in the bottle. 1
Received jsnuary 14, 1924.
