47 



10. Forest-covered loess. In Sample 1, 300 grams of soil 

 were hydrolyzed and diluted in the same manner as Sample I of 

 prairie-covered loess. In Sample II, 300 grams of soil were hy- 

 drolyzed under the same conditions as Sample II of prairie-covered 

 loess. The nitrogen retained by the barium phosphotungstate was 

 0.0024 gram in Sample I, and 0.0023 gram in Sample II. The 

 solution containing the nitrogen of the bases was Diluted to 100 

 cc. in both samples and the solutions containing the total nitrogen 

 of the filtrates were made to a volume of 300 cc. 



It is observed that the volume of acid used in the hydrolysis 

 had little effect on the proportion of the different fractions. The 

 only observed difference is in the insoluble humin nitrogen retained 

 by the soil residue, and this is slightly larger in Sample II, which 

 was hydrolyzed in the presence of the greatest excess of acid. In 

 connection with this it must also be noted that there is a somewhat 

 larger quantity of nitrogen in solution in Sample II than in Sample 

 I. Much the same results are shown with the prairie-covered loess. 

 All increases or decreases in the various fractions due to the greater 

 excess of acid may well be considered to be within the experimental 

 error. 



The experimental data showing grams of nitrogen found and 

 per cent of total nitrogen are given in Table XIII. 



Table XIII. Nitrogen distribution in forest-covered loess. 



By difference 



Calculated. 



1 1 . Sphagnum-covered peat hydrolyzed in the presence of nine 

 times its weight of a mineral subsoil. Duplicate 10 gram samples 

 were hydrolyzed in the presence of 90 grams subsoil with constant 

 boiling hydrochloric acid for 48 hours. The hydrolysate was con- 

 centrated as much as possible and ammonia nitrogen determined 

 on the entire mixture by distillation with an excess of calcium hy- 

 droxide for one hour.* 



*This was the first attempt to determine the nitrogen fractions in the 

 presence of a mineral soil. For certain reasons later analyses have already 

 been reported in this paper. The analyses as reported in this paper are 

 by no means in chronological order, which may explain seeming 1 inconsist- 

 encies. 



