July 14, 1916] 



SCIENCE 



65 



ing an opposite rotation. For example, 

 Z-borneol acetate with a specific rotation of 

 — 44.4° could yield ethyl acetate and borneol 

 with a specific rotation of — 37.8° Z-menthol 

 acetate, with a specific rotation of — 79.4°, 

 yields Z-menthol having a specific rotation of 

 — ■ 50°. The change of rotation in these two 

 cases is in the same direction as that of Z- 

 menthone and would be added to it. In other 

 cases, however, the changes might be in the 

 opposite direction. The change in rotation due 

 to the borneol acetate, for example, can be 

 calculated from the ester number, which is 

 always determined, and the proper correction 

 can be made. 



The same idea can be applied to the calcu- 

 lation of the amounts of each of two esters 

 whose identities are known and whose changes 

 of rotation by sodium ethylate are different or 

 of opposite sign. The ester number and change 

 of rotation will give the amount of each. 

 When the mixtures become complex the " un- 

 knowns " become too large and the method 

 becomes only qualitative at best. 



W. A. Gruse, 

 S. F. Aceee 

 Dept. op Chemistry op Forest Products, 

 University op "Wisconsin 



measuring biological actions by the 



freezing-point method directly 



in the soil 



It has already been shown that the freezing- 

 point method can be employed to measure (a) 

 the concentration of the plant-cell sap directly 

 in the plant tissue, 1 (b) the concentration of 

 the soil solution at different moisture contents, 

 directly in the soil,- 2 and (c) the effect of 

 application of soluble chemical compounds 

 upon the soil solution. 2 In the present note it 

 is desired to announce that the freezing-point 

 method can be used also to study biological ac- 

 tivities, by measuring the products of decom- 

 position of organic materials, directly in the 

 soil. 



In conjunction with the experiments on the 

 effect of the application of soluble chemical 

 •compounds upon the concentration of the soil 



i J. Am. Soc. Agr., Vol. 8, No. 1, 1916. 



2 Tech. Bull. No. 24, Mich. Expt. Sta., 1916. 



solution, the effect of the decomposition of 

 various nitrogenous substances was also stud- 

 ied. It has been found that the products of 

 decomposition of these nitrogenous substances 

 increased markedly the concentration of the 

 soil solution, and the magnitude of the increase 

 varied with the nature of the compound and 

 amount employed. In the following table 

 there are presented the results of a single ex- 

 periment which might serve to typify the char- 

 acter of the general data obtained. This ex- 

 periment consisted of mixing 0.5 and 1.0 

 grams of dried blood, cotton-seed meal and ani- 

 mal tankage with 800 grams of soil (equivalent 

 to about 1,250 and 2,500 pounds per 2,000,000 

 pounds of soil respectively), allowing the mix- 

 ture to stand in room temperature for five 

 weeks at optimum moisture content and then 

 determining the freezing-point depression, ac- 

 cording to the method already described in 

 Tech. Bull. No. 24 of this Station. The per- 

 centage of nitrogen contained by the materials 

 is as follows : dry blood, 14.14 per cent. ; cotton- 

 seed meal, 7 per cent., and animal tankage, 10 

 per cent. 



table i 

 Effect of Decomposition of Nitrogenous Sub- 

 stances Upon the Freesing-Point Depression 

 of the Soil Solution 



Substance 

 Dry blood . . . 



Animal tankage 

 Cotton-seed meal 



1.0 



.030° 



The depression in every case is the difference 

 between the depression of the untreated soil or 

 check and that of the treated. In other words, 

 the check was used as a standard. 



It will be seen then that the decomposition 

 of these nitrogenous materials increased the 

 depression, and hence the concentration of the 

 soil solution, markedly, and the magnitude of 

 the increase seems to vary with the nature of 

 the material and quantity employed. 



In some other experiments the amounts of 

 these nitrogenous materials were used, not in 

 equivalent weight but in equivalent nitrogen 

 content and the freezing-point depression was 



