378 BOARD OF AGRICULTURE. 



both, find Joillbauer for the determination of nitrogen in materi- 

 als containing nitrates have been tried to qnite an extent, with some- 

 what unsatisfactory results. These modifications are now being 

 iiiven a systematic trial, the results of which are reserved for future 

 publication. 



Determination of the Character and Value of the Orrjanic Nitrogen 

 in Fertilizers. The possible sources of the organic nitrogen in fertil- 

 izers are numerous. This form of nitrogen may come, for instance, 

 from blood or from leather, both of which materials are in the market, 

 but which ditfer greatly in value, not onlv commercially, but as a 

 source of available plant food. It is very important to know whether 

 commercial fertilizers contain organic nitrogen in such poor forms as 

 leather, hair, wool, etc. 



The Report of the Connecticut Experiment Station for 1885 con- 

 tains results of a studN' of a method proposed by previous inves- 

 tigators for the determination of the value of organic nitrogen in 

 fertilizers, viz : The digestion of the fertilizer with a pepsin solu- 

 tion for a given time, and the subsequent determination of the nitro- 

 gen not brought into solution. The figures so far as published show 

 that nitrogenous organic materials have a comparative digestibility in 

 a pepsin solution that accords fairly well with the supposed com- 

 parative agricultural value. 



AVith a view to making a practical application of this method in 

 the inspection of fertilizers, Mr. Merrill has determined the per- 

 centage of organic nitrogen in eleven of the leading fertilizers sold 

 in Maine, that remains undissolved b}' the pepsin solution. 



Previous to doing this, however, and as a preparation for the work 

 on fertilizers, and to compare his results with those of others, rather 

 than to take up a stud}' begun by others, Mr. Merrill submitted quite 

 a number of nitrogenous materials to the pepsin digestion*. 



These materials were obtained for the Station through the kind- 

 ness of fertilizer manufacturers, and the only description that it is 

 possible to give of them is the name under which the}' appeared in 

 the markets. 



Unless otherwise mentioned, these substances were passed through 

 a sieve with 1-25 inch meshes before disrestion. 



o 



♦The pepsin solution was made by dissolving 5 prrams of scale pepsin in 1000 c. c. of .2 per 

 cent hydrochloric acid. T\vo grains of the substance were digested for 12 hours on each of two 

 consecutiTe 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 hydrochloric acid were added at regular 

 intervals until the digestive fluid contained 1 per cent of the acid. 



