1133 



out in duplo, without changing (he sulphuric acid tubes. In (his 

 wa}' eacli absorbing tube got four times (he amount of NH, of one 

 test-tube. On each day the Soja extract was fieshlj' prepared as 

 described above. 



The necessary correction for the traces of NH,, which might 

 have been given off by the Soja-nieal, the phosphate or the pot- 

 assium carbonate, was determined by placing each day 3 times 10 cc. 

 of extract E into 3 empty test-tubes and after the addition of 25 cc. 

 of potassium carbonate, blowing over tiie NH, in the same manner 

 into absorbing tubes, filled with 5 cc. of H,SO, Veo ^ and water. 

 Each of these absorbing tubes thus received 6 times the amount of 

 this correction. 



The estimation of p^ was made electrometrically in the air-thermo- 

 stat of 27°, as described further on in this paper. 



In the present case for 10 cc. extract E, mixed with 2 cc. water 

 jt?^= 7.515. 



10 cc. of extract E, mixed with 2 cc. of urea solution (0.06 7o) 

 after 4 hours standing at 27° gave /;^:= 7.525. 



As the Ph on a total hydrolysis of 0.01 V^ urea in 8Vo phosphate 

 showed the slight increase of 0.01, it was taken here as 7.52. 



The titration was carried out directly in the wide absorbing tube 

 with YsoNNaOH, prepared shortly before with distilled water, 

 freed from carbon dioxide and Vio^NaOH solution, prepared and 

 .and kept free from CO,. 



A very dilute solution of sodium alizarin sulphonate proved again 

 to be the best indicator for NH, estimations. Cleaning of burettes 

 and pipettes with bichromate and sulphuric acid directly before use 

 is absolutely necessary in this kind of work. 



Jan. 17-18 1917. 



TABLE 1. 



0.01 o/o urea. 



(Fig. 2 A) 

 pH = 7.52 



