686 
Journal of Agricultural Research 
Vol. V, No. is 
the material, after which most of the ether was removed by exposing the 
veal to the air in large crystallizing dishes. The veal was then heated 
in the hot-water oven at 85° C. (flame out) for two hours, and bottled. 
Beef sample 1.1: Fourteen hundred grams of beef sample 1 were 
treated with alcohol and ether in exactly the same way as veal sample 
1.1, using 1,400 c. c. of alcohol, etc. 
When portions of these powdered-meat preparations were weighed 
for digestions, portions were also weighed for moisture determinations, 
so that the final weights were based on the dry material. Total nitrogen 
per gram of beef sample 1.1, 57.2 c. c. iV/5 nitrogen; per gram of veal 
sample 1.1, 57.8 c. c. iV/5 nitrogen. Other analytic data are given in 
Table V. 
first method: weighing the undigested meat residues 
Portions of 5 gm. each of the raw hashed beef and veal were weighed into 200 c. c. 
Erlenmeyer flasks. After adding 40 c. c. of water to each flask and stirring, the flasks 
were kept in a boiling-water bath for 1 hour. They were then cooled, weighed, and 
the evaporated water replaced. To each flask 50 c. c. of 0.4 per cent hydrochloric 
acid were added, followed shortly afterwards by the addition of 10 c. c. of the pepsin 
solution. Three flasks containing beef and three containing veal were generally used 
in a single experiment (see Table VIII). In the controls on the acid 10 c. c. of water 
instead of the pepsin solution were added. 
The digestion was considered to have begun when the pepsin was added. During 
the digestion period the flasks were rotated occasionally, so as to mix the contents. 
When the digestion period had ended, the filtration of the residue, consisting of undi¬ 
gested meat, fat, etc., was begun. For this purpose loose-textured filter papers 
(Schleicher & Schull’s No. 589, white band, 15 cm.) were used. These papers, con¬ 
tained in weighing bottles, had previously been dried for several hours at 95 0 C. in 
the hot-water oven until the change in weight after a second drying was slight. Dry¬ 
ing such papers to absolutely constant weight was as difficult as drying meat to con¬ 
stant weight without decomposition or oxidation. 
It is at this point that the worker loses control over the method. When filtration 
was rapid, which sometimes happened, the separation of undigested meat from the 
pepsin-hydrochloric-acid solution ended the digestion period quite sharply, so far 
as the residue was concerned. But, as was generally the case, filtration was slow 
because the residue was gelatinous and clogged the filter, and it was not possible to 
end the digestion period shortly after filtration was begun because digestion continued 
as long as the pepsin-hydrochloric-acid solution was in contact with undigested meat. 
Fortunately, the digestive process becomes slow as the meat approaches complete 
digestion, so that the error from this source probably amounts to less than 10 per cent 
of the correct result. 
When filtration was complete or nearly so, the residues were washed with water, 
transferred with the paper to the corresponding weighing bottles, and dried to ap¬ 
proximately constant weight at 95 0 C. in the hot-water oven. From the data for 
moisture, the original 5-gm. portions of fresh meat were calculated to the dry weight. 
The weight of the dry, undigested residue divided by the corresponding weight of 
dry meat gave the percentage of beef or veal present as undigested residue (see “ Per¬ 
centages of meat digested,” p. 700). 
Acid proteinate. —The value of the determination of acid proteinate in digestion 
mixtures has been pointed out by Gies (Hawk and Gies, 1902). The first step in the 
