112 EXPERIMENT STATION RECORD. [Vol.36 



cobaltinitrite and so interfere with tlie results. This can be avoided, however, 

 by the addition of sodium citrate, which will keep the phosphates in solution 

 during the cobaltinitrite precipitation. 



The estimation of calcium, E. Cahen and W. H. Hurtley {Biochem. Jour., 

 10 {1916), No. 2, pp. 308-312). — The residue after the destruction of the organic 

 matter in certain biological materials was found to be completely soluble in 

 sulphuric acid only after prolonged heating. By using phosphoric acid the 

 authors succeeded in effecting complete solution after only a few minutes of 

 heating. The method is described as follows : 



The organ or tissue is dried at 100° C. and incinerated in the usual way. 

 Liquid samples are first evaporated on the water bath, dried at 120°, and then 

 incinerated as usual. To the residue 20 cc. of phosphoric acid of specific 

 gravity 1.2 (one volume sirupy phosphoric acid to three volumes water) are 

 added if much calcium is present ; if only a little is present 10 cc. or even less is 

 used. On warming the calcium dissolves completely. This liquid is diluted 

 with 50 or 100 cc. of water, according to the amount of calcium present, 

 and the calcium then precipitated by a solution of oxalic acid of proper 

 strength, about five times the theoretical amount of acid being added. Pre- 

 cipitation is rapid and the precipitate is crystalline, but a little calcium re- 

 mains in solution. To effect complete precipitation ammonia equal in strength 

 and voliune to the oxalic acid used is added. If magnesium is present the 

 ammonia must be added slowly and with shaking. The precipitated solution 

 is allowed to stand for one hour, after which it filters quickly and perfectly 

 clear. The calcium is then determined either by a slightly modified volumetric 

 procedure, or by the usual gravimetric procedure. 



Comparative experimental data indicate the accuracy of the procedure. 



A new color reaction for " oxy cholesterol," Mary C. Rosenheim (Biochem. 

 Jour., 10 {VJI6), No. 2, pp. 176-182. i)L 1). — A color reaction of cholesterol with 

 technical dimethyl sulphate is described, the spectrum of which shows two 

 absorption bands. The reaction is not given by pure dimethyl sulphate and is 

 deemed due to the presence of monomethyl sulpliate in the technical product. 

 " Oxycholesterol " was found to give a purple color reaction with technical 

 dimethyl sulphate which showed an absorption band in the yellow. A typical 

 green reaction was obtained with oxycholesterol and pure or technical dimethyl 

 sulphate after the addition of ferric chlorid showing a well-defined absorption 

 band in the rod. 



Note on the detection of crude beet sugar in cane products, H. Pellet 

 (Bui. Assoc. Chim. Suar. et Distill., S3 (.1916), No. 7-9, pp. 169-171).— The 

 presence of even small amounts of crude beet sugar in cane products is un- 

 desirable on account of the disagreeable taste and odor it imparts to the 

 product. The taste, however, is not always a satisfactory indication of the 

 presence of the beet products. Analytical data of the nitrogenous content of 

 crude cane and beet sugars show a decidedly greater quantity in the beet 

 product. It is indicated that the observations reported may serve as a means 

 of detecting the presence of the crude beet sugar in the cane prodiicts. 



A simple and rapid method for the estimation of volatile acid in wine, 

 W. v. Crukss and R. W. Bettoli [Off. Rpt. Sess. Inteniat. Cong. Vit., 1915, pp. 

 263-267). — A simple method for the determination of volatile acids in wine, 

 suitable for the ordinary wine maker, is described. It consists essentially of 

 estimating the total acid in the untreated wine, then in the wine after driving 

 off the acetic acid, and tluis calculating the volatile acid by difference. 



The improved procedure, briefly described, consists of decolorizing about a 

 75-cc. sample with bone black free from carbonates. The completely decolor- 

 ized wine is then filtered and a 20-cc. sample titrated with teuth-uormal alkali 



