RECENT WORK IX AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of crude fiber in cereals, J. N. Huety 

 (Chem. Ztg., 21 (1897), No. 50, p. 491). — Having' a large number of 

 samples of coarse wheat flour to analyze in a short time, the author 

 employed the following method: Two grams of air-dry flour was boiled 

 in a half-liter flask with 200 cc. of saturated salt solution and 5 cc. of 

 hydrochloric acid of 1.16 specific gravity until the starch was inverted, 

 which required about 10 minutes. After filtering through a Gooch 

 crucible the residue was washed first witli hot water, then with 200 cc. 

 of hot 2 per cent sodium hydrate, and finally with water, alcohol, and 

 petroleum ether. The residue was dried at 110°, weighed, ignited, and 

 the ash deducted. In 5 trials the average by the official method was 

 2.48 per cent and by the " salt method" 2.53 per cent of crude fiber. 

 In 5 comparisons on bran the official method gave an average of 11.84 

 per cent and the salt method 11.91 per cent of crude fiber. The time 

 required for making the determination, exclusive of drying and igniting, 

 was about 20 minutes. 



The determination of phosphoric acid, H. Lasne (Bui. Soc. Chim. 

 Paris, 3. ser., 17 (1897), No. 16-17, pp. 823-832).— This is a summary of 

 results obtained in experiments during several years to determine the 

 influence of varying conditions upon the accuracy of the determination 

 of phosphoric acid by precipitation with magnesium salts in the pres- 

 ence of ammonium citrate. The questions studied were the influence 

 of the length of time allowed for precipitation, the accuracy of the 

 determination when mechanical agitators were used, the influence of 

 the dilution of the solution, and the causes of plus errors in the deter- 

 mination under certain conditions. 



The conclusions reached are briefly as follows: The determination of 

 phosphoric acid in the form of pyrophosphate by the above method with- 

 out any precaution except the previous removal of the silica gives accu- 

 rate results as a rule. In rapid precipitation a plus error is observed, 

 due to the formation of tri-7nagnesium phosphate, which is not entirely 

 transformed into ammonium-magnesium phosphate unless the solution 

 contains a sufficient amount of ammonium citrate (10 gm. of citric acid 

 to 150 cc. of the solution) and is allowed to stand at least 16 hours. In 

 order, therefore, to obtain absolutely accurate results the solution after 



415 



