The soy bean contains as its chief proteid constituent glycinin, a globulin similar in properties to legumin, but of somewhat dif ferent composition, containing nearly twice as much sulphur, four-tenths per cent. more carbon, and one-half per cent. less nitrogen. We give as the composition of this proteid the results of our analysis of preparation 9, which was obtained from a neutral and perfectly clear extract, for we believe that this represents more accurately the true composition of glycinin than the average of all the preparations. The soy bean contains a more soluble globulin which resembles phaseolin in composition, and, so far as we could ascertain, also in its reactions. The amount of this proteid is small and the evidence that it is in reality phaseolin was not wholly satisfactory. Besides these globulins about one and five-tenths per cent. of the albumin-like proteid legumelin was obtained. We have found legumelin in a number of other leguminous seeds, the pea, vetch, horse bean, lentil, adzuki bean, and cow pea. The properties of legumelin are given in our papers on "The Proteids of the Pea, Lentil, Horse Bean, and Vetch." The composition of legumelin as found in the soy bean is as follows: 1 This Journal, 20, 410. A small quantity of proteose was also obtained from the soy bean having the following composition: Owing to the small amount of proteose no evidence was obtained as to the purity or individuality of this preparation. ELECTRICAL DISTURBANCE IN WEIGHING. WHILE BY H. K. MILLER. Received February 28, 1898. WHILE making some fat determinations, I found a practice, which I believe is quite common among chemists, to be the source of quite serious errors. The practice is that of wiping a flask with a dry cloth just previous to weighing it. In making a second weighing of a flask containing an oil which had been extracted from a sample, I was very much surprised to find a considerable increase over the weight first obtained. The first idea that presented itself was that the oil had suffered oxidation during the second heating, but this idea was dispelled when to my greater surprise a third weighing showed the flask and contents to weigh even less than at first. Careful experiments led to the conclusion that in wiping the flask it became electrified, and that this static charge, acting on the floor of the balance, induced on it a charge of opposite character, and that the mutual attraction between these two charges of electricity had the effect of apparently increasing the weight of the flask. The potential of the charge would vary with the atmospheric A high charge like this, however, would be rapidly dissipa- Proof for the accuracy of the process. I. Obtaining a solution from the steel of ammonium phosphate con- taining all the phosphorus and only a faint trace of iron..... Precipitation of ammonium phosphomolybdate.. Note on the difference in ammonium phosphomolybdate precipi- II. The precipitation of phosphorus as magnesium ammonium phos- The use of magnesium chloride, ammonium chloride,and ammonia 442 1 In this paper I have recorded a number of experiments upon the estimation of phosphorus in steel. Their subject is a study in detail of the molybdate-magnesia method. Some of the experiments are upon properties of the molybdate precipitate, which are not connected with this method for estimating phosphorus. The concluding pages describe precipitation of phosphoric acid, out of measured quantities of a standard III. Obtaining a correct weight of magnesium pyrophosphate.. 447 448 449 HESE experiments were made with steel of low carbon content (below 0.10). The preparation of the solutions of the steel for the molybdate precipitation applies to soft steel. The remainder is of general application in steel analysis. These steels do not contain arsenic, and I have not considered the separation of arsenic and phosphorus, except incidentally. THE SAMPLES. A volume of liquid steel is throughout of practically uniform composition, and the percentage of phosphorus in all parts of it is the same. LADLE TESTS FROM A TWENTY THOUSAND POUNDS HEAT OF BESSEMER STEEL, WHICH WAS POURED INTO Three Molds. On the other hand, it is sometimes difficult to obtain drillings from a billet or finished shape, which accurately represent the composition. Incorrect opinions have doubtless been drawn of the relation between physical properties and chemical composition, and also with regard to the accuracy of methods, from neglect to remember the facts of segregation. The four samples of steel employed in this work were planed from the surface of billets, rejecting the first portion. The planings from sample No. 1 were mixed and bottled. The others were prepared as follows: The planings were sieved in a coffee strainer, the dust rejected, and the remainder mixed and bottled. The dust for each was about one-twenty-sixth of the whole. Estimations of phosphorus in drillings, made at about twelve places on the surface of the billet from which sample No. 1 was planed, showed that segregation had taken place to a limited extent. ESTIMATIONS OF PHOSPHORUS IN THE DUST AND COARSER PARTICLES. The determinations in different parts of the fluid mass, and in the particles of different size planed from billet surfaces, were made by titration of ammonium phosphomolybdate with potash solution. As the point of the plane passes over a portion of the surface at which phosphorus has segregated, more dust is formed than from the remainder of the surface, which is softer and less brittle, and the dust sifted out will be higher in phosphorus, if there is segregation upon the surface. That the more brittle. portions of a surface will yield the larger proportion of dust is evident; it has also been referred to by Von Jüptner', who quotes experiments of Leopold Schneider. In spite of slight segregation on some of the surfaces from which samples were planed, they are regarded as fairly uniform owing to their subsequent treatment. This applies to all of the samples but No. 1. I have been able to use some of the results from No. 1, but not all. Continued tilting of the jar containing the sample, concentrated the dust at the bottom. Removal of the fine portion would not appreciably change the percentage of phosphorus, but concentration to three times the original amount would raise the percentage of phosphorus 0.001 per cent., assuming that the phosphorus in both coarse and fine portions for samples Nos. I and 2 are the same, both having been planed from the same face. PROOF FOR ACCURACY OF PROCESS. After obtaining a solution of the sample in nitric acid and oxidizing it, it is possible to determine the accuracy of the steps in the molybdate-magnesia method, by carrying the pyro1 Oest. Zeit. Berg u. Hütten., xiv, 159, per J. Iron and Steel Inst., 1896, No. 2, 439. |