AGRICULTURAL CHEMISTRY — AGROTECHNY. 713 



The ignition of precipitates without the use of the blast lamp, P. H. 

 Walkee and J. B. Wilson (U. 8. Dept. Agr., Bur. Chem. Circ. 101, pp. 8). — "An 

 attempt has been made to determine whether alumina and silica can be ignited 

 to constant weight without the use of a blast lamp, and as a result the authors 

 are of the opinion that with slow initial ignition and final heating at the highest 

 temi)erature that can be obtained with a burner, silica is practically always 

 reduced to constant weight in 2 hours and generally in 1 hour. Alumina re- 

 quires a somewhat longer period. About 3 hours reduces the weight to within 

 the limit of error of the determination." 



Precipitating agents for amino acids, C. Neuberg and J. Kekb (Biochem. 

 Ztschr., JfO (1912), No. 5-6, pp. /i98-502). — A universal precipitating agent for 

 amino acids was found in a solution of mercuric acetate made alkaline with 

 sodium carbonate. If to a solution of glycocoll, a saturated or a 10 per cent 

 solution of sodium carbonate is added to alkalinity and then followed with a 25 

 per cent solution of mercuric acetate a white precipitate is obtained. By the 

 judicious addition of the reagents in turn and then alcohol, a dense white pre- 

 cipitate is produced which is nearly quantitative. The process consists not only 

 in obtaining the mercuric salt of the amino acid but also represents a com- 

 plicated reaction in which the elements which constitute carbon dioxid come" 

 into play. Probably the basic salts of the corresponding carbamic acids are 

 involved. The method does not possess the sharpness or definiteness of phos- 

 photungstic acid with the diamiuo acid.s, 



A delicate method for determining minute quantities of chlorophyll, C. A. 

 Jacobson (Jour. Amcr. Chem. Soc, 3Jf (1912), No. 9, pp. 1266^1209, pis. //).— 

 A description is given of a method for determining the quantity of chlorophyll 

 in leaves with a green weight less than 1 gm. This consists of a comparison 

 of the intensity of the chlorophyll absorption bands of the solution to be ex- 

 amined with the intensity of the corresponding bands produced by solutions of 

 known concentrations. 



Colorinaetric determination of phosphoric acid in ax'able soils, C. R. Her- 

 RERA (An. Inst. MM. Nac. [Mexico], 10 (1908), pp. 271-276; abs. in Chem. Ahs., 

 6 (1912), No. 5, p. 662).— The method is as follows: 



" Twenty gm. soil, dried at 110°, are heated to low redness in a platinum 

 crucible to destroy organic matter and digested with nitric acid on a water 

 bath for 5 hours with frequent shaking. The filtered solution is evaporated 

 to dryness in a platinum dish, the oxids of iron and aluminum dissolved in 

 o cc. each of nitric acid and water, and filtered from silica. The temperature 

 should be kept below 120° in order to prevent formation of alkali and alkaline 

 earth silicates which would later form silicomolybdates. The filtrate is precipi- 

 tated with ammonium molybdate, the precipitate dissolved in ammonia and, 

 after addition of iwtassium feri'ocyanid, compared with a standard solution 

 prepared from pure acid sodium phosphate. Citrate-soluble phosphoric acid 

 may be determined in a similar manner." 



Determination of moisture in cereals and cereal products, A. Fornet 

 (Ztschr. Gesam. Getreideic, 3 (1911), Nos. 4, pp. 92-98; 5, pp. 113-118; h 

 (1912), No. 3, pp. 73-77, figs. 3).— This is a study of methods. It considers the 

 various temperatures and apparatus proposed for determining the moisture in 

 cereals and cereal products, and also points out their disadvantages, particu- 

 larly the Duvel (E. S. R., 18, p. 1122) and Hoffmann api>aratus. 



The author also describes a rapid drying apparatus, which utilizes a current 

 of air and a temperature of 160° C. He finds that working under these con- 

 ditions the apparatus will furnish results in from 7 to 14 minutes, depending 

 upon the material under examination, which are practically identical with 



