Jan. io, 1916 
Mature Beef and Immature Veal 
691 
replaced in the bath. The quantities of N/j sodium hydroxid used varied from 18 
to 29 c. c. The neutralization is satisfactory when a flocculent precipitate appears. 
In the same way 100 c. c. of the digestion fluid from the beef mixture were removed 
and neutralized 60 minutes after starting the beef digestion. 
In this way portions of the digestion mixtures of beef and veal were removed for 
neutralization on the minute, at intervals of 1, 2, 4, 7, and 24 hours. Fifteen min¬ 
utes before neutralization the flask contents were mixed and allowed to stand for 10 
minutes. A 100 c. c. portion was then removed from the bulk of the digestion mix¬ 
ture 5 minutes before neutralization. 
The precipitated acid proteinate was filtered, washed, and nitrogen was determined 
by the Kjeldahl method. The results obtained are given in Table IX under the 
heading "Quantity of iV/5 acid-proteinate nitrogen /’ 
The filtrate was transferred to a Kjeldahl flask and the total nitrogen determined. 
This filtrate contained nitrogen derived from (1) the proteoses and peptones formed 
by the digestion of the meat, (2) the extractives present before digestion began, and 
(3) the pepsin. The figure for total nitrogen obtained on the filtrate is the sum of 
these three. The data recorded in Table IX under the heading "Quantity of Nj$ 
proteose and peptone nitrogen 17 are the figures actually obtained and corrected for the 
sum of the extractive and pepsin nitrogen. Thus, in experiment 14 the results 
obtained for one hour’s digestion of beef sample 3 were, for the precipitated acid pro¬ 
teinate, 2.7 c. c. of JV/5 nitrogen; for the filtrate, 23.8 c. c. From this latter figure 
there was subtracted 8.0 c. c., this being the sum of the extractive nitrogen in that 
sample of beef at that time, and the nitrogen present in the pepsin added. The method 
of determining extractive nitrogen is described on page 673. 
During the digestion the water contained in the meat is liberated and dilutes the 
digestion fluid to a slight extent. No correction for this was made, except in those 
particular cases where the correction is indicated. 
The "theoretical maximum 77 for proteose and peptone nitrogen in 100 c. c. of 
digestion fluid was calculated in the following manner: The sum of the total nitrogen 
in 100 gm. of fresh meat plus the pepsin nitrogen was divided by the volume of the 
digestion fluid at complete digestion—i. e., 2,000 c. c. plus the volume of water in the 
100 gm. of meat. 
By the term " Age of meat, days, 7 ' at the bottom of Table IX is meant the number of 
days the meat was in cold storage before being boiled. Thus, in experiment 21 beef 
sample 6 and veal sample 6 were hashed and boiled after 13 days in cold storage, and 
on the next day digestion was begun. These figures do not refer to the age of the calf 
when killed, this having been given in Table I. 
It will be noticed that the theoretical maximum for proteose and peptone nitrogen 
is approximately 50 c. c. of iV/5 nitrogen in nearly all the experiments. In order fo 
obtain the percentage of nitrogen present as proteoses and peptones at any time, it is 
only necessary to multiply the corresponding figure by 2. Thus, in experiment 
19, at the end of seven hours approximately 82 per cent of the veal (41.0-5-48.0) had 
been transformed into proteoses and peptones. It is obvious that both the beef and 
the veal were digested with practically the same speed and that at the end of 24 hours 
the transformation into proteoses and peptones was complete. 
For practical purposes the digestive process may here be regarded as taking place 
in two stages: (1) The transformation of the native meat proteins to acid proteinate 
by combination with the hydrochloric acid, and (2) the cleavage of the acid proteinate 
into the smaller molecules of proteoses and peptones. 
The data in Table IX indicate that both processes took place with equal speed in 
the beef and veal. 
The undigested residues weighed in experiment 13, Table VIII, probably contained 
very little nitrogen. The concentration of pepsin in experiments 9 to 13 was the same 
