302 AGRICULTUEAL EXPERIMENT STATION. [Jan. 



During the early summer of 1893 several samples oi 

 leather were received at the station. It was stated that 

 large quantities of the material were on the market, and one 

 could surmise, at least, that it might be used as a source 

 of nitrogen in the manufacture of commercial fertilizers, 

 organic nitrogen at the time being quite high in price. It 

 was thought wise to submit the samples to several tests, 

 and, for the sake of comparison, pure sole-leather, obtained 

 by the writer at the cobbler's, and dried blood were also 

 included. 



Description of the Samples. 



I. Sole-leather. — This leather was ground fine for future 

 tests. Under the microscope it showed a distinct fibrous 

 structure. It contained 2.76 per cent, of fat and 7.94 per 

 cent, of nitrogen. 



//. Steamed Leather. — Some of the finely ground leather 

 was placed in pressure bottles, water added, and heated for 

 six hours at 110 ° C. The leather was virtually subjected to 

 three atmospheres of steam pressure. After treatment it 

 had become very dark in color, and appeared as a jelly- 

 like, amorphous mass. The microscope showed it to be 

 devoid of any fibrous structure. The tannic or gallic acids 

 were still easily recognized, showing that they had not been 

 destroyed by the heat and pressure. When dry it became 

 quite brittle, crumbling easily. 



///. Coarse Leather sent to the Station. — This leather 

 came in pieces, from the size of a walnut to that of a small 

 hen's Q^^. It contained 37.47 per cent, of fat and 4.52 per 

 cent, of nitrogen. The large amount of fat completely con- 

 cealed its structure. 



IV. Philadelphia Tankage. — The sample was very 

 finely ground and quite dry. It contained 1.95 per cent, of 

 fat, 7.80 per cent, of nitrogen and traces only of phosphoric 

 acid. Its smell and general appearance indicated clearly 

 that it was leather that had been roasted or steamed. To 

 tUe eye it appeared to be lacking in fibrous structure, and 

 with the microscope it appeared simply as a gelatinous mass. 

 V. Dried Blood. — It was an excellent sample, contain- 

 ing 12.71 per cent, of nitrogen and .64 per cent, of fat. 



