Oct. 14, i9i8 Chemistry of Sweet-Clover Silage 125 



(4) The fact that sweet clover shows smaller differences than alfalfa 

 in these respects indicates that this protein hydrolysis takes place 

 to a less extent in sweet clover than in alfalfa. This would mean 

 that under practical conditions good silage is more readily made from 

 sweet clover than from alfalfa. The addition of corn meal to sweet 

 clover did not seem to have any distinct advantage. Silage from sweet 

 clover alone was as good as that made from sweet clover and corn meal. 

 With alfalfa the addition of corn meal was an advantage, as shown in our 

 previous work.^ 



NITROGEN IN AMINO (NHo) FORM 



TITRATIONS WITH THEl HYDROGEN ELECTRODE 



It was Stated that when making the determinations for acidity the 

 hydrogen-ion concentration had been reduced to Ph9-3, or the theoretical 

 points of color change for th}rmolphthalein, 25 cc. of the formaldehyde 

 solution was added and the titration resumed till the hydrogen-ion con- 

 centration was again Ph9-3- This second titration should give figures 

 for calculating the nitrogen in amino form. Whether this is the case is a 

 question which we do not attempt to answer in the present paper. Accord- 

 ing to Sorensen,^ who first elaborated the method, the titrations should 

 first be carried to tke neutral point for phenolphthalein, or Ph8.3, then 

 the formaldehyde solution added, and the titration repeated till the point 

 of color change for thymolphthalein, or Ph9-3 is reached. The number 

 of cubic centimeters of N/20 sodium hydroxid used in this second titra- 

 tion multiplied by 0.7 give the number of milligrams of titrable nitrogen 

 in the mixture. If this is correct, the results of the electrometric titra- 

 tions as we made them are too low for amino nitrogen when the number 

 of cubic centimeters obtained in this last titration are multiplied by 0.7. 

 But as both the Ph8.3 and the Ph9-3 points were determined in the 

 titrations for acidity, a correction can be introduced. This is done in 

 Table VI. In the A columns are given the number of cubic centimeters 

 used in the second titration after the formalin (HCHO) was added to 

 bring the Ph value again to the 9.3 point. In Table V is given the dif- 

 ferences in titrations between titrating to Ph8.3 and Ph9-3- By adding 

 these differences to the figures in the A columns of Table VI, the figures 

 given in the B columns are obtained. These figures should be the same 

 as if the titrations had been first carried to the Ph8.3 point in the acidity 

 titration and then formalin added and then the titration resumed till 

 the Ph9-3 point was reached. That this assumption is correct is sub- 

 stantiated by some work done by us on the changes which take place in 



» SwANSON, C. 0., and Tagub. E. L. Op. cit. 



*S6rensen. S. p. L. Enzymstudien. In Biochem. Ztschr., Bd. 7, Heft H, p. 45-101. 1907. 



Allen's Commercial Organic Analysis . . . ed. 4, v. 8, p. 478, 488. Philadelphia, 1913. 



