30 MAINE STATE COLLEGE 



THE QUALITY OF THE NITROGENOUS MATERIAL IN THE SUPERPHOS- 

 PHATES SOLD IN MAINE. 



The possible varieties of nitrogenous material available for use 

 in the manufacture of superphosphates are numerous. Nitrate of 

 soda, sulphate of ammonia, dried blood, dried and ground flesh of 

 animals and fishes, cotton-seed meal, ground horn and hoof, hair 

 and wool waste and prepared leather, are some of the substances, 

 which in various forms and under various names, supply nitrogen 

 to our mixed fertilizers. These materials vary greatly in value, 

 both commercially and as plant food. This fact has been the 

 cause of uncertainty in the valuation of the nitrogen in superphos- 

 phates. 



Reliable methods of analysis can be used to separate the 

 organic nitrogen (nitrogen coming from animal or vegetable 

 iBatter) . from that existing as nitric acid or ammonia, the latter 

 forms being readily available plant food. But it has not been so 

 easy to ascertain the quality of the organic nitrogen, whether from 

 dried blood or horn, from meat or leather. It is has been darkly 

 hinted now and then that a great deal of inferior nitrogenous 

 material is used by the manufacturers of fertilizers, though no 

 proof of this has been furnished to the public. 



P^xperiment stations have assumed that the organic nitrogen of 

 mixed fertilizers is supplied in the best forms, and have valued in 

 accordingly, but it has been recognized, at the same time, that 

 some way of detecting inferior forms is extremely desirable. The 

 method for doing this which has received most attention is based 

 upon the different degrees of solubility of organic nitrogen com- 

 pounds in a pepsin solution. The nitrogen of dried blood, dried 

 flesh, cotton-seed meal and similar high grade nitrogenous 

 materials is very largely dissolved by digestion in a pepsin solution, 

 while that of horn, hoof and leather is much less affected by this 

 treatment. 



In support of this statement there is given below the results of 

 experiments conducted in three different laboratories for the 

 purpose of testing the value of this method.* With regard to 

 most of the materials used, these results are practically in accord. 



* The method of treating the substances was briefly as follows : The pepsin solution was 

 made by dissolving 5 grains of scale pepsin in 1000 c. c. of .2 per cent, hydrocholic acid. 

 Two grams of the substance were digested for 12 hours on each of two consecutive days 

 with 200 c. c. of this solution, at a temperature of 40 degrees C. During the time of 

 digestion 2 c. c. of a ten per cent, solution of hydrocholic acid were added at regular 

 intevals until the digestive fluid contained i per cent, of the acid. 



