380 



BOARD OF AGRICULTURE. 



In treating the eleven mixed fertilizers previously mentioned with 

 the pepsin solution, the method alread}' described was followed, ex- 

 cept that before digestion the two grams of fertilizers were thrown 

 on a filter and leached with 75 c. c. of water added in repeated small 

 quantities. Additional samples were leached in the same way and 

 the organic nitrogen soluble in water was determined. 



* Total nitrogen soluble in water minus the nitrogen from nitrates and ammonia salts. 



In none of these fertilizers does the organic nitrogen show so low 

 a solubility as to plainly indicate that its source is leather, hair, wool, 

 or any substance of the same grade, but it is very clear that in some 

 cases the ammoniates used are not of such high grade as dried blood, 

 or the various forms of prepared meat. Nos. 7 and 9 may derive 

 their nitrogen from fish scrap or from a mixture of high and low 

 grade materials. So great is the variation in the solubilit}' of fairly 

 liigh-grade ammoniates that it seems impossible to decide by this 

 method whether the organic nitrogen is or is not in part derived from 

 low-grade ammoniates. For this reason the names of the mixed fer- 

 tilizers used for the above determinations are not mentioned. 



