AGRICULTURAL CHEMISTRY — AGROTECHNY. 713 



It is also generally conceded that the nonvolatile acid is present in the larger 

 quantity in silage. The purpose of this work was to determine how much of 

 the nonvolatile acidity (usually calculated as lactic acid) is actually due to 

 lactic acid, to determine the optical forms in which it occurs, and to ascertain 

 whether the kind of silo has any Influence upon the amount and character of 

 the lactic acid produced. In the work the zinc lactate method was employed. 



The experimental data showed that lactic acid is present in silage under nor- 

 mal conditions and in excess of the volatile acids. The average ratio was 

 1 : 0.75. The acid occurs in the optically inactive or racemic mixture form. In 

 order to determine whether racemization did not occur under the experimental 

 conditions employed, samples of the optical form of acid were prepared, but it 

 was found that neither the levorotatory or dextrorotatoi'y forms of acid were 

 changed under the conditions which prevailed during the experiment. 



The importance of hydrocyanic acid and glucosids as producers of hydro- 

 cyanic acid in plant chemistry, A. Jobissen (Bill. Soc. Chim. Bclg., 26 (1912), 

 No. 5, pp. 199-205; abs. in Chem. 7Ag., 36 {1912), No. 117, Repert., p. 526).— 

 A historical resume of the occurrence of hydrocyanic acid in the plant world 

 is followed by a review of the newer work, which is discussed critically. 

 Special emphasis is placed upon the results obtained by Belgian investigators 

 in regard to cynuogenesis. 



Studies on enzym action. — III, The action of manganous sulphate on 

 castor bean lipase, K. G. Falk and M. L. Hamlin (Jour. Amer. Chem. Soc. 

 35 (1913), No. 2, pp. 210-219). — This continues work previously reported 

 (E. S. R., 27, p. S02) in which it was stated that the activation of lipase was 

 probably due to some oxidation reaction. Hoyer<^ having found that the addi- 

 tion of manganous sulphate increased the activity of lipase, tests were made 

 to determine whether the manganous salt was an oxygen carrier and was capa- 

 ble of activating castor bean lipase by an oxidation reaction. 



" The main conclusion to be drawn from the experiments described is that 

 the castor bean lipase preparation after having been inactivated by heating 

 with water was rendered active again to a small extent by manganous sulphate. 

 Attempts were made to use oxygen carriers other than manganous sulphate, 

 but those tested, including ferrous sulphate, hydrogen peroxid, and potassium 

 persulphate, showed themselves such marked hydrolytic action on the ester 

 that the testing of the preparations after such treatment gave results of no 

 value. 



" The formation of acid in the treatments to which the preparations were 

 subjected could not have been the cause of the observed activities, as the ex- 

 periments where manganous sulphate was absent did not show the activities 

 even with the increased acidities. In order to account for the accelerating 

 action of manganous sulphate on castor bean lipase, as observed by Hoyer and 

 by Tanaka (E. S. R., 28, p. 610) and in the experiments described in the pres- 

 ent paper, the following tentative explanation is offered : The inactive zymogen 

 of lipase in castor beans is converted into the active enzym by an oxidation 

 reaction for which the presence of an oxygen carrier or catalytic agent is 

 necessary. Simultaneous hydrolysis may or may not be involved in this re- 

 action. The active enzym is converted into inactive material by hydrolysis, 

 slowly at low temperatures in aqueous solution or suspension, rapidly at higher 

 temperatures. Presumably all of the substances involved in these changes, 

 inactive zymogen, active enzym, inactive product from enzym, are protein in 

 character. 



« Hoppe-Seyler's Ztschr. Physiol. Chem., 50 (1907), No. 4-5, pp. 414-435, 



