286 AGRICULTURAL EXPERIMENT STATION. [Jan. 



wool, silk and leather clippings. The process as described 

 was as follows : the refuse was introduced into an ordinary 

 autoclave digester, and there kept for about three hours, 

 surrounded by steam heated to a pressure of from three to 

 live atmospheres. Wool required a higher temperature than 

 leather, and silk than wool. The materials condensed a por- 

 tion of the steam and absorbed its heat. This joint action 

 converted the animal matter into a friable substance, which, 

 however, still retained its original form and aspect. It was 

 then ground fine, sifted and bagged. "The details of the 

 process, the fuel and labor-saving arrangements that have 

 been learned, point by point, by costly manufacturing ex- 

 perience, cannot," says Ward, " with propriety be divulged." 

 The final product is described as a dark-colored powder. 

 The nitrogen in the finished product is said to exist to a 

 small extent as ready formed ammonia, being in combination 

 with ulmic and humic acids developed during the process. 

 It was stated at the time that this manufacturing process was 

 carried on at large works on the Thames. The material for 

 the most part was sold to manure manufacturers, who used 

 it as an ingredient of their several fertilizing compounds, 

 and it was " used by many farmers who are not aware of the 

 fact." Ward says that, " while this material is not as active 

 as some other forms of organic nitrogen, it possessed distinct 

 vahie as a fertilizer."* 



Edw. Toynbec,f in 1858, also described a process wherebj' 

 leather and wool waste could be cooked in sulphuric acid, 

 and be made more available as a fertilizer. He said that ' ' to 

 one centner of sulphuric acid four or five centners of wool or 

 leather waste could be added." The writer does not see how 

 such a large amount of leather could be added to the acid, as 

 will be shown further on. L. Meyer | speaks of dissolving 

 all such refuse substances in warm sulphuric acid, and neu- 

 tralizing the moist mass with bone. 



A. Lipowitz § notes the fact that the Posner fertilizer 



* The writer does not know whether this process is still in operation in England 

 for utilizing the leather, wool and silk wastes. 



t Repertory of Patent Inventions, 1858, page 389. Jahresbericht Agric. Chem., 

 1859, 



J Jahreshericht Agric. Chem., 1859, 228. 



§ Allgem. Zeitung fur deutsche Land, und Forstwirthe, 1859, 153. 



