AGRICULTURAL CHEMISTRY — AGROTECHNY. 207 



Phosphomolybdic acid as a reagent for the chemical and microchemical 

 detection of adulteration in saffron, A. Verda (Chem. Ztg., 38 (1914), No. 30, 

 pp. 325-327). — Saffron adulterated with drugs having microscopic characteris- 

 tics simih^r to saffron and others having only similar coloring powers were 

 studied. 



When treated with a solution of phosphomolybdic acid saffron gives a beauti- 

 ful green color. The test may be used microchemically, and thereby differen- 

 tiates saft'ron from other substances. Tbe reaction is said to be dependent upon 

 crocin, a glucosld present in saffron. 



The estimation of tannin in cider, C. W. Spiers (Jour. Agr. Sci. [England}, 

 6 (1914), No. 1, pp. 77-83). — ^The various methods in use by chemists and 

 botanists are criticized, especially those for determining tannin in cider. The 

 use of fat-free casein to remove the tannin is recommended since it removes 

 nothing else. 



"Although it was found that the strychnin method of Trotman and Hackford 

 [E. S. R., 17, p. 530] is not accurate in the case of gallotannic acid, the tannin 

 in cider is quantitatively precipitated by strychnin after careful neutralization. 

 This is shown by the fact that there is a parallelism between the results ob- 

 tained by this method and by the permanganate titration method ; although in 

 the absence of a method of quantitative precipitation of a standard gallotanuiu- 

 strychnin compound, the strychnin precipitate results can not be expressed 

 as gallotannin comparably with those of permanganate titration." 



The amount of tannin removed is determined by the loss in permanganate 

 value on titration. The solutions of tannins studied lost their tannin on shak- 

 ing 50 cc. with 1 gm. of casein for 15 minutes. The i^ermanganate solution was 

 istudied with various commercial tannins and 1 gm. of ammonium oxalate was 

 found to be equivalent to 0.4648 gm. of tannin. 



" The preparation of the tannin of apples is now being undertaken, so that it 

 is hoped to standardize both the permanganate solution and the strychnin pre- 

 cipitate by the pure apple-tannin itself." The results of analyzing ciders, 

 healthy and sick, and mostly of tbe bitter-sweet variety, are presented. 



Minimal content of total nitrogen of milk, A. Kling (A»m. Falsif., 6 

 {1913), No. 56, pp. 340-342; abs. in Chem. Ztg., 38 {1914), No. 26, Repert., p. 

 116). — ^The method propo.sed by Roy and the author for the detection of 

 adulterated milk is considered accurate by A'uaflart (E. S. R., 31, p. 810), who, 

 however, believes that the total protein content of milk sbould be taken as 29 

 gm. per liter and of fat as 30. The author thinks that the figures proposed may 

 be correct for the north of France, but that in the Department of the Seine and 

 the adjacent departments materially higher values prevail. 



The determination of the titer of arsenite solutions, E. Deiss (Chem. Ztg., 

 38 {1914), No. 39, pp. 413-415). — lodin solutions containing iodates may under 

 certain circumstances yield erroneous figures for the titer of an arsenite solu- 

 tion. A method is suggested for preventing this, namely, by adding acid to de- 

 stroy the iodate formed. By the use of a permanganate solution of known 

 strength, however, reliable figures may be obtained in a short time without 

 doing this. 



Vineg'ar making, F. T. Bioletti {California Sta. Rpt. 1914, P- 194)- — Many 

 complaints have come to the station regarding failures to obtain vinegars of 

 standard strength and quality from apparently good raw material. Imperfect 

 fermentation seemed to be the cause of most of the trouble. A table is presented 

 which gives the results of fermenting apple juice with pure yeast and sulphurous 



79934°— No. 3—15 2 



