1918] AGRICULTURAL CHEMISTRY AGROTECHNY. 311 



The data are presented in tabular form and discussed. 



Some nitrogenous auxoamylases, E. W. Rockwood {Jour. Amer. Cliem. Soc, 

 39 (1911), No. 12, pp. 2745-2752).— From experimental data submitted, it is 

 concluded that both acyclic and cyclic compounds increase the power of the 

 salivary ferment to hydrolyze boiled starch. In the cyclic compounds the action 

 is the same whether the amino group is in the side chain or whether in the ben- 

 zene ring. The salts from which the amino acids are derived do not have this 

 action, thus indicating that the amino nitrogen is the activating agent. The 

 position of the amino group in the benzene ring does not appear to cause any 

 difference in activity. Acid amids, urea, etc., do not increase the hydrolytic 

 power of the amylase. The sulphonic acid radical, when introduced into an 

 amino compound instead of the carboxyl group, destroys the stimulating effect 

 of the amino group. Imids do not possess this stimulating power. 



Proteins are considered to act as auxoamylases toward ptyalin because of 

 their nitrogen content, and as the number of free amino groups is increased by 

 hydrolysis the activity of the hydrolyzed substances is also increased. 



" The amino acids appear to act as auxoamylases toward the pancreatic 

 enzym also. Hence the amino acids produced in the intestine by digestive pro- 

 teolysis will act as hormones in starch digestion, and this factor should be taken 

 into account in the study of normal digestion. " 



See also a previous note (E. S. R., 37, p. 204). 



Analytical control of the ammonia oxidation process, G. B. Taylor and J. D. 

 Davis {Jour. Indus, and Engin. Cliem., 9 {1917), No. 12, pp. 1106-1110, figs. 2).— 

 In the course of some experiments on the oxidation of ammonia for the pro- 

 duction of nitric acid the authors have developed several analytical procedures 

 for determining the course of the reaction. These procedures are described and 

 discussed in detail. 



A method for the determination of ammonia nitrogen with formaldehyde, 

 G. H. C. VAN Bers {CJiem. WeekU., U {1917), No. 42, pp. 968-975).— The fol- 

 lowing procedure for the determination of ammonia nitrogen in ammonium 

 sulphate is described : 



Five gm. of the ammonium sulphate is dissolved in water and the solution 

 made up to 100 cc. and filtered. Ten cc. of the filtrate is transferred to a 

 small Erlenmeyer flask, and 1.2 cc. of a 35 per cent formaldehyde solution 

 (specific gravity 1.083 at 15° C.) and 10 cc. of ^(y -normal potassium hydroxid 

 added. The flask is well stoppered, and the contents thoroughly shaken and 

 allowed to stand overnight. Fifty cc. of boiled distilled water is added and 

 the excess alkali titrated with tenth-normal sulphuric acid, using phenol- 

 phthalein as indicator. The proper corrections should be made for the acid in 

 the solution and also in the formaldehyde. The percentage of nitrogen in the 

 material is calculated by subtracting the number of cubic centimeters of tenth- 

 normal acid, plus the acid found in the blanks, from the number of tenth- 

 normal cubic centimeters of alkali used, and multiplying the difference by 

 0.2802. If the quantity of nitrogen in the sample is less than 19 per cent 

 some slight modifications are necessary. 



The procedure is considered to yield as accurate results and to be less time 

 consuming than the usual distillation procedure. The use of a burner is also 

 eliminated. 



The use and value of various indicators in ammonia titrations are briefly 

 discussed. 



The determination of potassium and sodium in the ash of vegetable sub- 

 stances, H. Pellet {Ann. Cliem. Analyt., 22 {1917), Nos. 7, pp. 146-152; 9, pp. 

 179-185). — To ash the material it is recommended to incinerate at a low heat 



