AGRICULTURAL CHEMISTRY AGROTECHNY. 307 



meet in a gelatin jelly strata there ensues a deep violet color with no 

 turbidity. 



Detection of traces of chlorids in commercial gelatin, R. E. Liesegang 

 (Ztschr. Chem. u. Indus. KoUoide, 5 (1909), No. 5, pp. 2-'f9, 250).— Slight 

 traces of chlorids in gelatin can not be detected by the addition of silver nitrate. 

 The author proposes taking a 10 per cent solution of gelatin, allowing it to 

 solidify on a glass plate, and then adding several drops of a 10 per cent silver 

 nitrate solution in the same manner as described in his work with jellies. The 

 reaction only becomes ai)parent after a time, when at the periphery of the drop 

 there appears at first a turbidity which gradually becomes greater until it may 

 reach a diameter, according to the size of the drop, of 1 to 2 cm. 



The recognition of flour adulterations by the serum method, W. Magnus 

 (Landw. Jahrb., 3H {1909), Eig<in::u)ifj><h. 5, pp. 207-215; abs. in Chem. ZentM., 

 1909, II, No. 11, p. 936). — The author describes a method to utilize the precipitin 

 reaction to detect adulterations of flour with products from closely related 

 plants and nonrelated plants. In the case of closely related plants, rye and 

 wheat, the specificity was good. Three per cent of rye in wheat flour could be 

 easily recognized. 



The ash content of honey, A. Rohrig (Bcr. Chem. Unter.'nich. Anst. Leip- 

 zig, 1908, p. 34; abs. in Ztschr. Untersuch. Nahr. u. Genussmtl., 18 {1909), No. 

 8, p. Ji82). — Pure honeys had an ash content between 0.068 and 0.284 per cent. 

 The average of 38 samples was 0.136 per cent. In artificial honey it was not 

 always under 0.1 per cent and in fact in four cases it was from 0.18 to 0.292 per 

 cent. .ludging honey on these grounds may often lead to error. 



[Qualitative and quantitative methods for] the detection and determina- 

 tion of sulphurous acid in lime juice, E. Dowzaud (Antcr. .Jour. I'hurm., 81 

 {1909), No. 12. pp. .507 -.7';/, ) .—The official qualitative method ( E. S. R., 19, p. 

 506) is modified by adding phosphoric acid to the reagents, distilling off 50 cc. 

 of the juice, and collecting the distillate in a 1 per cent solution of sodium 

 bicarbonate. The modified quantitative method consists in shaking out with 

 chloroform the essential oil from this distillate, and titrating the aqueous por- 

 tion in the usual manner. 



A rapid method of determining- sulphurous acid in wine, Dujardin {Feuille 

 Vin. Gironde, 34 {1909), No. 46, p. 184, fit)- i)- — A specially constructed volu- 

 metric tube termed " the sulphuro-onemetric tube " is used. The reagents 

 employed are a solution of iodin, potash, starch, etc. The i"esults are given in 

 milligrams per liter. 



The determination of ethereal oil and eugenol in cloves, R. Reich {Ztschr. 

 Untersuch. Nahr. u. Genussmtl., 18 (1909), No. 7. pp. 401-412, fig. 1).—The best 

 cloves have a high oil and eugenol content, but the essential oils from them 

 show a lower percentage of eugenol than those obtained from inferior cloves 

 and clove powders, the reason for this being that the former oils contain more 

 esters and ketones. The author, therefore, considers the determination of 

 eugenol important. 



On analysis Amboina cloves were found to contain 21.3 to 22.1 per cent of 

 oil, whereas Zanzibar cloves contained 18.4 to 20.1 per cent. The respective 

 eugenol contents were 17 to 17.6 per cent and 15.4 to 16.6 per cent. With pure 

 ground commercial cloves the oil content fluctuated between 17 and 19.3 per 

 cent and that of eugenol between 15.5 and 16.3 per cent. Clove stems showed 

 only 5.8 to 6.7 per cent of oil and 5.4 to 5.7 per cent of eugenol. Examination 

 of oils distilled by the author gave a minimum eugenol content of 79 per cent 

 and a maximum of 87.9 per cent. 



28918— No. 4—10 2 



