604 Wisconsin Academy of Sciences, Arts, and Letters. 
was then determined by the modified Kjeldahl method used 
throughout this work. Non-protein or ‘‘amide’’ nitrogen was 
obtained by subtracting the value found from the total nitro¬ 
gen. 
Two catches which have not been included in the preced¬ 
ing determinations were also examined at this point. The per¬ 
centages of protein and non-protein nitrogen are recorded be¬ 
low. 
Sample 
Total 
nitrog-en 
Protein 
nitrogen 
Non-protein 
nitrogen 
Protein 
(N X6.25) 
A. 
6.15% 
3.93% 
2.22% 
24.56% 
B........ 
5.58 
4.62 
0.96 
28.87 
C. 
8.25 
3.83 
4.42 
23.94 
D... 
8.55 
3.50 
5.05 
21.87 
E... 
9.94 
8.67 
1.27 
54.18 
154. 
8.85 
4.47 
4.38 
27.94 
5138. 
4.51 
2.82 
1.69 
17.62 
The following forms of nitrogen were determined by the 
method of Hausmann^: nitrogen as ammonia, “humic” 
nitrogen, and nitrogen in the mono-amino and di-amino acids. 
The sample was boiled with constant-boiling hydrochloric acid 
until it no longer reacted with the biuret test. Hydrolysis 
completed, the ammonia formed was distilled off with magnesia 
cream. The “humic” nitrogen was determined in the mag¬ 
nesium oxide precipitate. Di-amino nitrogen was then pre¬ 
cipitated from the filtrate with an acid solution of phospho- 
tungstic acid and the mono-amino nitrogen determined in the 
filtrate from the preceding. The latter form predominates in 
all the catches examined. The quantity of material available 
for this work has not made it possible to attempt a further dif¬ 
ferentiation of the proteins. 
A tabulation of the results follow: 
Sample 
Total 
nitrogen 
Nitrogen 
asNHs 
Di-amino 
nitrogen 
Mono-amino 
nitrogen 
"Ilumic” 
nitrogen 
A. 
6.15% 
0.70% 
1.22% 
3.69% 
0.39% 
B. 
5.58 
.70 
.96 
3.35 
.38 
C...... 
8.25 
.97 
1.90 
4.77 
.30 
D. 
8.55 
.76 
2.14 
5.16 
.32 
E... 
9.94 
1.09 
2.79 
5.39’ 
.67 
iZ. physiol. Chem. 27, 95 (1899). 
2 Obtained by difference. 
