Jan. io, 1916 
Mature Beef and Immature Veal 
679 
Ammonia. —The Boussingault-Shaffer method, as described by Berg 
and Sherman (1905), was used for the determination of ammonia 1 in 
the hydrolytic mixture. The apparatus used was, in general, similar to 
that used by Van Slyke (1911, p. 21). 
Fifty c. c. of the hydrolytic mixture, corresponding to 5 gm. of meat, 
were used. It was desired to know whether the general assumption 
that no nitrogen is carried over by the hydrochloric-acid distillate was 
correct or not. For this purpose the distillates from beef, whenever 
obtained, were transferred to the same Kjeldahl flask, while the distil¬ 
lates from veal were transferred to another. The total nitrogen was 
then estimated in the usual manner. Distillates corresponding to 25 
gm. of beef and 35 gm. of immature veal yielded in both cases less than 
0.2 c. c. of iV/5 nitrogen, indicating that none was lost during the 
distillations. 
The distillation of the ammonia was carried out as usual for one hour 
in every case, during which time there appeared to be no splitting off of 
“cleavage ammonia,” as numerous tests indicated. 
In the hydrolytic mixtures obtained from beef and veal the ammonia 
nitrogen was about 7 per cent of the total nitrogen. Because of the 
small amount of ammonia actually distilled, corresponding to 5 gm. of 
fresh meat, or about 1 gm. of protein, the unavoidable errors in the 
analyses are proportionately large. The differences between six dupli¬ 
cates on beef and veal samples 8, 10, and 11 (Table V) varied from 
0.04 to 1.33 per cent of the total nitrogen; average, 0.5 per cent. An 
idea of the limits of accuracy of this determination may be obtained by 
comparing the figures for ammonia nitrogen in casein by Van Slyke 
(1912, p. 297), who found 10.1 and 10.27 per cent, with those by Sher¬ 
man and Gettler (1913), who found 10.0 per cent. 
In order to be better able to compare the results for ammonia nitrogen, 
etc., in beef and veal with similar results by other workers, a sample of 
pure casein was hydrolyzed, using 5 gm. of casein instead of 25 gm. of 
fresh meat. The results obtained were: On casein hydrolyzed for 24 
hours, 10.04 an d 10.38 percent, and for 48 hours, 10.55 an d 10.81 percent, 
of the total nitrogen present as ammonia, indicating that the technic used 
was essentially similar to that used by the above investigators (see p. 682). 
Melanin nitrogen. —To the mixture remaining in the distillation 
flask after the removal of ammonia 3 c. c. of concentrated hydrochloric 
acid were added, the material transferred to a 100 c. c. volumetric flask, 
and diluted to the mark. This was then filtered into a second clean, 
dry 100 c. c. flask, and the nitrogen was determined in the melanin on the 
filter paper, corresponding to 5 gm. of meat, by the Kjeldahl method in the 
usual manner. To the figure so obtained there was added the amount 
of melanin nitrogen occasionally obtained by filtering the hydrolytic 
1 For excellent discussions of the various methods for determining ammonia, see Smith (1913): also 
Shulansky and Gies (1913). 
