802 EXPERIMENT STATION RECORD. 



" Field tests made by using the pure arsenates at strengths as high as 8 lbs. 

 to each 100 gal. of water were tried for two consecutive seasons with no injury 

 to foliage. The lead hydrogen arsenate was found to react very easily with a 

 number of different substances, especially those of an alkaline nature. On the 

 other hand, the basic arsenate is a comparatively inert material. Tests made 

 with tent caterpillars showed the acid salt to be a much quicker acting poison. 



" The necessity of more complete methods for the true valuation of com- 

 mercial lead arsenates is pointed out. Satisfactory methods have been devised 

 for, and applied to, commercial samples as follows: (a) The estimation of lead 

 hydrogen arsenate in the presence of mixed salts, (b) the determination of 

 lead carbonate, (c) new methods for water-soluble arsenic oxid and water- 

 soluble impurities, (d) a method for acid insoluble impurities, and (e) the 

 detection of acetates and the quantitative estimation of chlorin. The appli- 

 cation of these methods shows a wide variation in the composition of the com- 

 mercial arsenates and gives a better valuation of them than the methods now 

 in use. 



" The precipitates obtained from the reactions of lead acetate and lead 

 nitrate with di-sodium hydrogen arsenate under certain conditions are mix- 

 tures of lead hydrogen arsenate and the basic lead arsenate. When hydrogen 

 arsenate is mixed with lime-sulphur in the proportions used in field practice, 

 a reaction takes place in which considerable quantities of lead sulphid and 

 calcium arsenate are formed, accompanied by the deposition of free sulphur. 

 Appreciable quantities of arsenic pass into solution due to the solubility of the 

 calcium arsenate. The reaction between lime-sulphur and the basic arsenate 

 is comparatively slight." 



Plant pigments, C. J. West {Biochem. Bui, i (1915), No. 13, pp. 151-160).— 

 A review of the chemistry of plant pigments other than chlorophyll. See also 

 a previous note (E. S. R., 31, p. 427). 



The organic phosphorus compounds of wheat bran, C. J. Robinson and 

 J. H. MxjELLEE (Biochem. Bui., 4 (1915), No. IS, pp. 100-117) .—The work is 

 divided into three parts. The first section deals with the results of a study 

 of the precipitate obtained by adding copper acetate to an extract of wheat 

 bran; the second, with the material resulting from the alcoholic precipitation 

 of bran extracts ; and the third describes a combination of the copper acetate 

 and alcohol precipitation methods. 



With Anderson's method (E. S. R., 33, p. 11) a tri-barium salt of phytin was 

 obtained crystalline in structure and identical in properties with that of 

 Anderson, but it corresponded more closely to the formula CoHi8024PeBa3. 

 Both in the case of the barium salt and the free acid the compounds obtained 

 appeared to contain six more hydrogen atoms to the molecule ; while in carbon, 

 barium, and phosphorus contents, they agreed very well with Anderson's 

 compounds. 



" There is in addition, a considerable amount of another substance, very 

 similar in composition, the barium salt of which contains only 34 per cent of 

 barium, instead of 38 per cent in barium phytate. The fact that this sub- 

 stance does not dialyze indicates that its molecule is larger than that of 

 barium phytate. 



" There is, finally, a compound differing widely from phytin in having more 

 carbon and less phosphorus in the molecule, which by hydrolysis splits off a 

 reducing sugar (pentose), and whose barium salt contains only about 31 per 

 cent of barium. We do not believe the composition of this substance has been 

 definitely fixed. It has not been obtained in crystalline form, the analogous 

 crystalline brucln salt prepared by Anderson probably being simply brucin 

 phosphate." 



