June 18,1917 
Methods of Estimation of Metabolic Nitrogen 
407 
tative filters. Wash beakers, filters, and contents until free from acid, 
with water at a temperature of 40° C. 
Return filters and contents to the proper beakers and treat with 100 
c. c. of alkaline-pancreatin solution (1.5 gm. pancreatin in somewhat 
less than 1 liter of water; add 3 gm. of sodium carbonate (NajCOg); 
dilute to exactly 1 liter, and mix thoroughly). Return the beakers to 
the bath and stir thoroughly. Allow to digest for exactly 12 hours. 
Filter immediately through fluted papers. Wash beakers, filters, and 
contents thoroughly and repeatedly with hot water, and allow to dry. 
Transfer the filters and contents to Kjeldahl flasks and determine the 
nitrogen in the usual manner. Subtract the result from total nitrogen 
of the feces; the remainder represents metabolic nitrogen. 
JORDAN’S METHOD 1 
Weigh 2 to 3 gm. portions of fresh feces, and dry at ioo° to 105° C.; 
transfer to extraction capsules and extract with ether for 16 hours. 
Transfer to 150-c. c. beakers and treat with 50 c. c. of boiling 95 per 
cent alcohol. Keep at boiling temperature for 10 minutes; decant the 
alcoholic extract through qualitative filters; wash several times with 
hot alcohol and once or twice with ether, by decantation. With a 
carneTs-hair brush transfer the residue from the filter papers to the 
original beakers; add 50 c. c. of hot water and boil for 10 minutes; filter 
through the same papers used for the last filtration, washing with hot 
water, by decantation. Wash the residues from the filter papers back 
into the beakers with 50 c. c. of a saturated solution of calcium hydrate, 
and let stand for 6 hours; filter through the same filters last used; transfer 
all the material from the beakers to the filter papers; wash with lime 
water, and allow to drain. Transfer filter papers and contents to Kjel¬ 
dahl flasks, and determine the nitrogen. Subtract result from total 
nitrogen of the feces; the remainder represents metabolic nitrogen. 
EXPERIMENTAL PROCEDURE 
The subjects of this experiment were five Yorkshire barrows of nearly 
uniform age and weight. The average weight at the end of the first 
period was 53.85 kgm., and at the end of the fourth, 59 days later, 
84.42 kgm., the average daily gain in weight being 518 gm., or 1.14 
pounds. They were confined in the metabolism crates illustrated in our 
previous publications. 3 
1 Jordan. W. H., Op. cat. (Detailed specifications were not submitted in the original publication; 
the particulars as here stated were arbitrarily assumed.) 
* Forbes. E. B. ( Beetle, F. M. t and others. A chemical study of the nutrition of swine. Ohio Agr. Exp. 
Sta. Bui. 271, p. 224-261, 3 pl. 1914* * 
---. The metabolism of organic and inorganic compounds of phosphorus. Ohio Agr. 
Exp. Sta. Tech. Bui. 6, Bo p. f illus. 1914. 
