AGRICULTURAL CHEMISTRY ^AGROTECHNY. 407 



and water, R. W. Clarke (Analyst, 36 {1911), No. 425, pp. S93-396).— The 

 Winkler method in the presence of nitrites and the Rideal and Stewart method 

 when used for the sewage before dilution are entirely unsatisfactory. If the 

 acid is neutralized in the latter method with magnesium carbonate, it can be 

 applied to the estimation of both dissolved oxygen and nitrites, but only when 

 some modifications are introduced. 



In regard to the temperature coefficients of the decomposition of invertase, 

 H. EuLEB and S. Kullbebg (Hoppe-Scyler's Ztschr. Physiol. Chem., 11 (1911), 

 No. 2, pp. 13^-142; abs. in ZentM. Biochem. u. Biophys., 11 {1911), No. 23, pp. 

 943, 944). — Continuing previous work (E. S. R., 26, p. 309), which was con- 

 ducted with an extract of dried yeast, the authors report the results with a 

 purer invertase preparation prepared from a juice obtained by autolysis. 



The results show a close agreement with those obtained previously, and 

 furthermore demonstrated that the proteins, peptones, carbohydrates, etc., 

 which are present in dried yeast, liave no or little influence upon the resistance 

 of invertase against a certain degree of heat, i. e., 63±0.2° C. 



It is furthermore noted that the temperature coefficient a, tlie constant of 



/, ^ M 

 stability I «^e~ / ''^ ST J' and particularly the thermal death point, which in a 



period of 30 minutes reduces the enzymatic activity (measured by the reaction 

 constant k) to one-half of a definite hydrogen ion concentration (10~®), are 

 values which can be accurately determined. The optimum temperature for 

 invertase obtained from top fermentation yeast lies 25° C. above that obtained 

 from bottom yeast. The stability of the enzyms in top yeast is also greater. 



Besearches concerning the composition of the wood and bark of a pear tree, 

 A. Manaresi and M. Tonegutti {Staz. Sper. Agr. Hal., 43 {1910), No. 10, pp. 

 714-717; abs. in Chem. ZentM., 1911, I, No. 5, p. 333; Chem. Abs., 5 {1911), 

 No. 16, p. 2663). — ^A branch from a 1-year-old pear tree having the leaves and 

 buds removed was examined, with the following results : The ratio of bark to 

 wood was 27.9 : 72.1. The substances determined were crude fiber, starch, pen- 

 tosans, nitrogen, ash, and ash constituents. Bark was found to contain 3 times 

 as much ash as the wood, was lower in phosphorus and iron, and richer in 

 silica and calcium. 



The chemical composition of the woods from different branches of fruit 

 trees, A. Manaresi and M. Tonegutti {Staz. Sper. Agr. Ital., 43 {1910), No. 

 10, pp. 75S-773; abs. in Chem. Zentbl., 1911, I, No. 5, p. 333; Chem. Abs., 5 

 {1911), No. 16, p. 2663). — ^'arious types of branches were analyzed, some old 

 and some young. Pear, apple, plum, and cherry twigs were used. The chem- 

 ical composition of the wood and ash was determined, and many tables of 

 analyses reported. 



The fruit-bearing wood was found much richer in nutrients than the foliage- 

 bearing wood. 



Short morphological and chemical studies of the foliage of different 

 branches of fruit trees, A. Manaresi and M. Tonegutti {Staz. Sper. Agr. Ital., 

 43 {1910), No. 10, pp. 7S7-794; abs. in Chem. Zentbl., 1911, I, No. 5, pp. 333, 

 334; Chem. Abs., 5 {1911), No. 16, p. 2663).— The leaves of branches from pear, 

 apple, plum, and peach trees bearing fruit and from others not bearing fruit 

 were examined as regards the comparative dimensions of the leaves and length 

 of stem. 



The leaves on the fruit-bearing branches were on the average longer stemmed, 

 longer, narrower, thinner, and richer in nutrients than the nonbearing branches. 



The chromogenic substances of white grapes, S. Dezani (Staz. Sper. Agr. 

 Ital., 43 {1910), No. 5, pp. 428-438; abs. in Jour. Chem. Soc. [London], 100 



32355°— No. 5—12 2 



