35 



In tho upi^licatlon of this method to soils 12 \)vy cont acid was used 

 instead of 2U per cent, as used l>y Osljorne and Harris. 



As stated above, boiling 10 grams of soil with 1()0 cubic centimeters 

 of 12 per cent hydrochloric acid for seven hours gave 0.()23 per cent 

 nitrogen in solution; and treatment of the insoluble residue for five 

 hours with 100 cul)ic centimeters 12 per cent sulphuric acid gave further 

 soluble nitrogen 0. 1 1 2 per cent. Tivatmentof the solutions so obtained 

 by the method stated gave the following figures: 



ForiiDi of nitrogai in acid extraclx. 



Hydrochloric- lU'iil solution: Percent. 



Nitrogen as ammonia 0. 119 



Nitrogen in magnesia precipitate -!^0 



Basic nitrogen t'^0 



Nonbasic nitrogen 084 



Total nitrogen in solution tJ-S 



Suiiilmrie acid solution: 



Nitrogen as ammonia None. 



Nitrogen in magnesia precipitate 105 



Basic nitrogen OOo 



Nonbasic nitrogen 002 



Total nitrogen in solution 112 



In comparing these tigures with those obtained by Osborne and 

 Harris working on pure protein bodies, the most striking point is the 

 large amount of nitrogen contained in the magnesia precipitate. In 

 the case of protein bodies it does not exceed 4 per cent of the total 

 nitrogen and in most cases is very nmch less; but in the soil solutions 

 it amounts to 45.2 per cent of the total in the hydrochloric acid solu- 

 tion and 93.7 per cent of total in sulphuric acid solution. Taking 

 both solutions, we have total nitrogen in solution 0. 735 per cent; 

 nitrogen in magnesia precipitate 0. 385 per cent, or 52.3 per cent of 

 total. 



This method has been applied to a number of soils with the same 

 general result. It has also been found that increasing the time of 

 boiling above two hours gave but slight increase in the amount of 

 nitrogen dissolved. For example, in one case the difi'erence between 

 two hours and fourteen hours was 0.080 per cent, and the amount of 

 nitrogen in the magnesia precipitate was in each case practically the 

 same. 



It seems a legitimate conclusion from this work that in the soil 

 nitrogen which is soluble in boiling acids a portion, approximately 50 

 per cent, is in a form unlike, for the most part, the products of decom- 

 position of protein bodies with acids. 



Practically the same result has been obtained by using barium 

 hydrate instead of magnesia. In a method proposed by Kossel and 



