separating eacli portion as carefully as possible from the others. The 

 greatest care was exercised in this preliminary work, inasmuch as the 

 value of the analytical data rests largely on the proper preparation of 

 the materials for examination. 



PREPARATION OP SAMPLES FOR ANALYSIS. 



The methods of preliminary treatment, together with the methods of 

 chemical analysis employed, are detailed in the following pages. Before 

 leaving Chicago each animal was cut up into the following cuts, the 

 head, leaf lard, and kidneys being retained in Chicago : 



Two American clear backs; two clear bellies; two short-cut hams; 

 two New York shoulders; four feet; spare ribs; tenderloins; neck 

 bones; backbones; trimmings, fat and lean; tail. 



These cuts were all weighed on leaving Chicago, and again in Wash- 

 ington just preceding their analysis. All of these weights appear in 

 the accompanying tables, pages 15 to 64. The weighings in Washington 

 were made on a large counter scale for the larger cuts, and on a torsion 

 balance in the case of the smaller cuts. The cuts were then separated 

 into the following parts: Meat (including both fat and lean), bones, 

 marrow, skin, spinal cord, tendons, and hoofs. 



Each of the parts, except the meat, was carefully weighed, and the 

 weight of the meat obtained by subtracting the sum of the other 

 weights from the total weight of the cut before cutting up. 



SAMPLES OF MEAT. 



The meat obtained from all of the cuts of the same kind in each 

 animal was passed through a meat chopper two or more times in order 

 to bring the sample into a finely divided condition. A weighed por- 

 tion was then placed in a weighed casserole or evaporating dish. A 

 glass rod was also weighed with the casserole. In the case of small 

 samples, as the tenderloins, the entire quantity was taken ; in the case 

 of the larger cuts, from 400 to 600 grams of the fresh material were 

 taken for the preparation of the air-dried sample. After the removal 

 of these portions for the preparation of the air dried sample, duplicate 

 portions of 5 grams each were weighed for the direct determination of 

 water and fat. These small samples were placed in aluminum dishes 

 and dried in vacuo for six hours at 105 degrees. The residues were 

 extracted for sixteen hours with ether, and the extracts dried in an air 

 bath at 100 degrees. These direct determinations of fat and water 

 were used as a check on the data obtained in the preparation of the 

 air-dry samples. The larger portions, which had been weighed out as 

 described above for the preparation of the air-dried samples, were placed 

 in a steam oven at a temperature of 100 degrees or slightly more and 

 heated until the fat had thoroughly separated, when the fat was poured 

 off into a flask, care being taken not to pour with it any of the aqueous 

 portion of the meat which formed a layer underneath the fat. After 



