122 



Journal of Agricultural Research 



Vol. XV, No. 3 



highly colored substances in solution than the water extract. That this 

 was the case was suspected in our former investigation. Concerning 

 this we said ^ : 



The figures for acidity are probably large The extract is highly col- 

 ored, and the end point is not easily read. 



DIFFERKNCES IN TITRATING TO THE HYDROGEN-ION CONCENTRATION Ph8.3 

 IN COMPARISON WITH Ph7; ALSO Ph9.3 IN COMPARISON WITH Ph8.3 



By substracting the figures in the first part of Table IV from the corre- 

 sponding figures in the second part, the diflferences between the quan- 

 tity of sodium hydroxid used in titrating to the hydrogen-ion concen- 

 tration Ph7 and Ph8.3 are obtained. Also, by subtracting the figures 



Fig. 3.^3raphs showing quantity, in cubic centimeters, of alkali used in alcoholic extract of silage- 

 comparison of colorimetric titrations with phenolphthalein, and electrometric titrations to Ph7. 



in the second part of Table IV from those in the third section the differ- 

 ences for the hydrogen-ion concentration Ph8.3 and Ph9-3 are obtained. 

 The figures so obtained are found in Table V for both the water extract 

 and the alcoholic extract. 



The data in Table show that — 



(i) The water extracts in comparison with the alcoholic extracts give 

 substantially the same results (fig. 3-5). 



(2) There is no significant change in the differences in the number of 

 cubic centimeters of NI20 sodium hydroxid used in titrating to a con- 

 centration, Ph8.3, in comparison with Ph7, as the silage matures — that 

 is, the difference between the two points tends to be constant. 



» SwAifsoN, C. O., and Tagcb, E. I». op. cit., p. ^84. 



