1895.] PUBLIC DOCUMENT — No. 33. 289 



From the many methods suggested for the utilization of 

 leather waste, it is evident that in the older countries, 

 specially England, France and Germany, this material, after 

 having been submitted to some mode of treatment, is quite 

 generally used, to a greater or less degree, in the manufact- 

 ure of commercial fertilizers. 



Petermann * says that "it is well known that certain Bel- 

 gian and French manufacturers use leather in their products, 

 but that such goods contain, in addition, nitrogen in other 

 forms, such as blood, horn, meal, sulphate of ammonia and 

 nitrate of soda." He further states that the " factories pro- 

 ducing this material are numerous, and a considerable quantity 

 is produced annually." 



2. Manuricd Value of Prepared Leather Waste. 



The different experiments made to prove the value of 

 leather have been conducted either with untreated finely 

 ground leather, with torrefied leather, or with leather 

 steamed under pressure. 



Three different methods have been used in testing the 

 agricultural value of leather: (a) by directly testing its fer- 

 tilizing effect cither in pot or plat experiments ; (J)) by arti- 

 ficially digesting it with a pepsin solution ; (c) by noting 

 the length of time required to nitrify it. The first method 

 is by far the most interesting, and leads to direct results. 

 The other two serve at least to confirm the results obtained 

 by the first method. 



A. Pot and Plat Experiments. 



Very early experiments are not to be found in literature. 



The first experiment recorded was made by Ladureau,f 

 and lasted but a single season. He found that 2,500 kilos, 

 of torrefied leather yielded 30,100 kilos, of sugar beets, 

 testing 8.83 per cent, of sugar; and 2,500 kilos, of the 

 same leather plus 200 hectolitres of lime gave 38,600 kilos, 

 of beets, with 10.10 per cent, sugar. The same area of land 

 without leather yielded 20,000 kilos, of sugar beets, testing 



* Recherches de Chimie et Physiologie [1885], 144. 

 + Ammles Agron., 1878; Loc. cit., 146. 



