1916] AGRICULTUEAI. CHEMISTRY AGROTECHNY. 207 



Genuine sirups have shown conductivity values as low as 96 and as high as 

 230. The limits of percentage variation of the conductivity value in genuine 

 sirups are much narrower than those of any of the older analytical values, 

 but not so narrow as those of the volumetric lead number. Additioijal analyti- 

 cal data on nonmaple sirups are reported. 



A comparison of methods for the determination of casein in milk, C. B. 

 Hebsey (Jour. Indus, and Engin. Chem., 8 (1916), No. 4, pp. SS5, 3S6). — 

 Although the official nitrogen method is the standard of accuracy for the 

 determination of casein in milk, the analytical results obtained show that the 

 Hart method (E. S. R., 19, p. 707) with electric centrifuge is dependable, 

 checking very closely the official method. It is deemed far superior to the volu- 

 metric method of Van Slyke and Bos worth (E. S. R., 22, p. 112). 



The Hart method possesses the advantages of requiring only a very little time 

 and neither exactly standard solutions nor final calculation of results. 



The occurrence and determination of creatin in the urine, F. H. McCbud- 

 DEN and C. S. Sabgent (Jour. Biol. Chem., 24 (1916), No. 4, pp. 42S-429). — 

 Exi)erimental data submitted indicate that " human urine contains a substance 

 or substances other than creatin which can give a color reaction similar to that 

 of creatinin on boiling with picric acid, and which, therefore, may appear in 

 the results as creatin." 



The reduction of Ass to Ass by cuprous chlorid and the determination of 

 arsenic by distillation as arsenic trichlorid, R. C. Roabk and C C. McDon- 

 NEix (Jour. Indus, and Engin. Chem., 8 (1916), No. 4, pp. 827-331, fig. 1). — 

 Experimental data indicate that ferrous salts effect only an incomplete reduc- 

 tion of Ass to Ass in hydrochloric-acid solutions. Satisfactory results can be 

 obtained only under certain conditions, usually with the presence of a small 

 amount of copper which forms cuprous chlorid, or when only very small amounts 

 of arsenic are present. Cuprous chlorid effectively reduces the arsenic in hydro- 

 chloric-acid solution and completely separates the arsenic trichlorid from anti- 

 mony, lead, copper, zinc, iron, and calcium. 



The method described consists of distilling a sample of the insecticide or 

 fungicide in a hydrochloric-acid solution with cuprous chlorid and, after neu- 

 tralization of the distillate, titrating the arsenic with standard iodin solution. 



New methods for the analysis of lime-sulphur solutions. — II, The esti- 

 mation of " polysulphur," R. M. Chapin (Jour. Indus, and Engin. Chem., 8 

 (1916), No. 4, pp. 339-341). — In continuation of the work previously noted 

 (E. S. R., 34, p. 806), the author has developed a new method for the estimation 

 of polysulphur which is claimed to be both accurate and convenient. 



The method, briefly outlined, consists of adding 10 cc. of k dilution of the 

 sample to 10 cc, of a recently prepared 10 per cent solution of C. P. anhydrous 

 sodium sulphite and 20 cc. of fifth-normal ammoniacal zinc chlorid contained 

 in a 200 cc. Erlenmeyer flask. Twenty-five cc. of water is added and the mix- 

 ture placed on the steam bath. At intervals of 10 minutes the contents of the 

 flask are agitated and the material adhering to the sides of the flask rinsed 

 down with a little hot water from a wash bottle. After heating for 45 minutes, 

 with four intermediate mixings, the flask is removed from the water bath and 

 20 cc. of a 10 per cent solution of crystallized strontium chlorid added. The 

 mixture is allowed to settle for 5 minutes and filtered into a 250 cc. volumetric 

 flask and the precipitate washed with hot water. The clear liquid is then cooled 

 to room temperature and from 0.5 to 1 cc. of a 10 per cent solution of crystallized 

 disodium phosphate added, made to the mark, well shaken, and filtered through 

 a dry paper into a dry flask, the flrst portions being used to thoroughly wet the 

 paper, and the runnings discarded. To 200 cc. of this clear filtrate methyl red 

 is added and then, slowly, vnth thorough mixing, a 10 per cent solution of 



