33 



The chemical analysis was made by the official method on soil which 

 had passed a 0.r)-millimeter sieve. 



The work outlined below, however, was all done with soil which 

 had passed a 1-millimeter sieve, the nitrogen content of which was 

 hig-her, viz, 0.868 per cent. Nitrogen determinations were made by 

 the Gunning method, without moditication to include nitrates, and 

 it is assumed that the small amount of nitrate present, 15 to 20 parts 

 per million, does not enter as a factor at all. Throughout, percent- 

 age of nitrogen is calculated on the basis of air-dried soil, e. g., in 

 the first example given below, total nitrogen in drainage 0.005 per 

 cent means 0.005 gram of nitrogen from KMi grams of soil. 



Despite the relativel}' large amount of nitrogen present, its extremely 

 insoluble condition is shown by the following figures: 



1. 1,000 grams of soil placed in a glass percolator; washed with 6,000 cubic; centi- 

 meters water in portions of 200 cubic centimeters. Total nitrogen in drainage, 0.005 

 per cent. 



2. 10 grams of soil l)oiled with 100 cubic centimeters water 1 hour, filtered and 

 washed to 500 cubic centimeters. Total nitrogen in filtrate, 0.022 per cent. 



3. 10 grams of soil treated in the cold with 100 cubic centimeters of 12 per cent 

 hydrochloric acid, for 1 hour, filtered and washed with 200 cubic centimeters acid, 

 and then with water to 500 cubic centimeters. Total nitrogen in filtrate, 0.002 per 

 cent. 



4. The residue from the treatment above was heated for 1 hour with 100 cubic 

 centimeters water at 125° C. ; filtered and washed to 500 (!ubic centimeters. Total 

 nitrogen in filtrate, 0.042 per cent. 



5. 10 grams of soil shaken for 2 hours with 100 cubic centimeters 95 per cent 

 alcohol, washed with 200 cubic centimeters alcohol. Total nitrogen in filtrate, none. 



6. 10 grams of soil shaken for 2 hours with 100 culiic centimeters 10 per cent salt 

 solution, filtered, and washed free of chlorids. Total nitrogen in filtrate, 0.006 per 

 cent. 



7. 10 grams of soil heated for 3 hours with 100 cubic centimeters water at 125° 

 C, filtered, and washed to 500 cubic centimeters. Total nitrogen in filtrate, 0.050 

 per cent. 



Hot acids and alkalis had a pronounced solvent action, as shown by 

 the following figures: 



1. 10 grams of soil boiled for 7 hours under a reflux condenser with 100 cubic 

 centimeters of 12 per cent hydrochloric acid, filtered, and washed free from acid. 

 Total nitrogen in filtrate, 0.623 per cent. 



2. The insoluble portion from the above treatment was digested (boiled) for 5 

 hours with 100 cubic centimeters of 12 per cent sulphuric acid, filtered, and washed 

 free from acid. Total nitrogen in filtrate, 0.112 per cent, leaving 0.133 per cent insol- 

 uble after two digestions with acid. 



3. 5 grams of soil were digested wath 1 00 cubic centimeters of water and 10 cubic 

 centimeters saturated solution cf caustic potash for 1 hour, filtered and washed. 

 Total nitrogen in filtrate, 0.728 per cent. . 



After these preliminary tests of solubility and behavior with reagents 

 the following somewhat hit or miss experiments were made with the 



31208— No. 170-06 3 



