18 MAINE STATE COLLEGE 



The degree of solubility for cheap and inferior "ammoniates" such as 

 horn, hoof, leather and wool waste is seen to vary from 4.8 per cent, to 

 37.8 per cent., while in the case of dried blood, cotton-seed meal, dried 

 and ground flesh, dried fish, fish scrap and ground bone the average per- 

 centages of the different trials range from 70.9 per cent, to 97.3 per cent. 



It is shown by the Conn. Experiment Station* that mixing with these 

 ammoniates mineral compounds of the kind and ill the quantity that 

 would be found accompanying them in superphosphates does not materi- 

 ally change their solubility in a pepsin solution, consequently it is fair 

 to conclude that the solubility in a pepsin solution of the organic nitro- 

 gen of a superphosphate will show whether this ingredient is furnished 

 largely in an inferior form. 



It was found in 1889, that the percentage of nitrogen soluble in 

 a pepsin solution varied in the several brands tested from thirty- 

 eight to seventy-eight per cent. This variation most certainly 

 indicated a radical difference in the character of the ammoniates 

 used by the various manufacturers, and it was thought wise to re- 

 peat this work with the goods offered for sale in 1891. Not 

 every brand of which samples have been taken in the market has 

 been submitted to this test, but there has been selected for this 

 purpose at least one brand from each manufacturer selling goods 

 in the State. The work was performed by Mr. Merrill with the use 

 of the following methods : 



The sample taken to represent a brand of superphosphate was 

 made up so as to represent the average of all the samples of that 

 brand selected this season. This was done, for instance in the 

 case of the Bay State Fertilizer, by weighing out equal quantities 

 of Nos. 755, 793 and 837, and thoroughly mixing them in a mor- 

 tar. One gram of substance was thoroughly leached with water 

 and then submitted to the action of a pepsin solution in accor- 

 dance with the method given below. The insoluble nitrogen 

 of the residue was then determined. | 



The percentages of organic nitrogen given are the total nitrogen 

 minus the nitrogen as nitric acid and ammonia. The tables which 

 follow explain themselves. 



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

 solution was made by dissolving 5 grams of scale pepsin in 1000 c. c. of .2 per 

 cent, hydrochloric 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 hydrochloric acid were added at regular intervals until the digestive fluid con- 

 tained one per cent, of the acid. 



[ Report Conn. Experiment Station, 1885, pp. 120-121.] 



