1916] AGRICULrUEAL CHEMISTRY — AGROTECHNY. 805 



Determination of the hardness of natural waters, and the use of methyl 

 red as an indicator, S. A. Kay and Susan H. Newlands {Jour. Soc. Chem. 

 Indus., 35 (1916), Xo. 8, pp. 445-W)- — Modified procedures for the determina- 

 tion of both temporary and permanent hardne^ss in water are described in 

 detail. It is indicated that the proposed methods are more accurate than those 

 now in common use. 



Determination of calcium and magnesium in natural waters, S. A. Kay 

 and Susan H. Xewlands {Jour. Soc. Chem. Indus., 35 {1916), No. 8, pp. ^1- 

 H9). — On the basis of certain preliminary experiments the authors have de- 

 vised a method for the determination of calcium and magnesium by (1) de- 

 termining the total hardness of the water, and (2) determining the hardness 

 due to calcium salts by evaporating the water with ammonium carbonate and 

 extracting the residue with ammonium carbonate solution, which dissolves the 

 magnesium carbonate, but is practically without action on the calcium car- 

 bonate. The amount of the latter is then ascertained by titration, and the mag- 

 nesium is determined by difference. 



Analytical data obtained from mixtures of known composition indicate the 

 accuracy of the method. 



Salicylic acid in wine, X. Rocques {Ann. Chim. Analyt., 21 {1916), No. 6, 

 pp. 117, 118). — The author observed that in certain natural wines some inter- 

 fering substance which masked the color of the delicate ferric chlorid test for 

 salicylic acid was present. This was later found to be tannin. 



To obviate this possible source of error the following procedure is described : 

 To 20 cc. of wine in a 250-cc. flask 0.5 cc. of sulphuric acid and, after thoroughly 

 mixing, 15 cc. benzin are added. The flask is then stoppered and without agita- 

 tion let stand until the next day. The salicylic acid is thus extracted by the 

 solvent and, on separating the benzin layer in a separatory funnel, can be 

 easily detected by the ferric chlorid test. This procedure will detect as small an 

 amount as 4 mg. of salicylic acid per liter of wine very clearly. 



The direct determination of sucrose in the presence of reducing sugars, 

 M. A. ScHNELLER {Louisiana Stas. Bui. 156 (1916), pp. 12). — Experiments are 

 described from which the conclusions previously noted (E. S. R.. 35. p. 316) 

 are drawn. 



A comparison of the results obtained by the colorimetric and gravimetric 

 determinations of cholesterol, J. H. Mueixeb (Jour. Biol. Chem., 25 (1916), 

 No. 3, pp. 549-560). — From a critical study of the two procedures for the deter- 

 mination of cholesterol it is concluded that either method is accurate when ap- 

 plied to solutions of pure cholesterol. The ether extraction with dried blood, 

 even when prolonged, was shown not to be complete. Hot alcohol or alcohol and 

 ether must be used. " Colorimetric analyses of blood give results too high for 

 true cholesterol, because they include other ether- and chloroform-soluble sub- 

 stances, whereas digitonin determinations are more nearly correct." 



A rapid method for the separation of butter fat from nonfatty material, 

 S. KoKPACZY (Ztschr. Intersuch. Nahr. u. Genussmtl. HO (1915), No. 1, p. 24). — 

 The usual method for preparing pure butter fat was found by the author to 

 consume too much time and to be subject to certain sources of contamination. 

 For the rapid preparation of pure butter fat the following procedure is recom- 

 mended : 



Forty gm. of butter and 10 gm. of pure, finely powdered calcined gypsum are 

 thoroughly mixed in a porcelain dish. This homogeneous mass is allowed to 

 stand for 10 minutes and is then placed in a drying oven where it is allowed to 

 melt slowly, after which it is rapidly filtered through a dry filter. It is indi- 



