45 



7. Carrington silt loam. Sample I (Nerstrand origin). The 

 hydrolysis of 250 grams was carried out according to the method 

 described under Fargo silt loam. The "humin" nitrogen was de- 

 termined as outlined under Fargo clay loam. Sample II (Morris- 

 town origin) was hydrolyzed and the same methods of analysis 

 employed throughout as was applied to- Sample I. The nitrogen 

 retained by the barium phosphotungstate precipitate was 0.0028 

 gram in Sample I and 0.0025 gram in Sample II. In both samples 

 the solutions containing the bases and nitrate from the bases were 

 made to the same dilution as under Fargo silt loam. 



The experimental data showing grams of nitrogen and per cent 

 of total nitrogen are given in Table X. 



Table X. Nitrogen distribution in Carrington silt loam. 



I Sample No. I | Sample No. II 



Solution lost at this point. 

 2 Result calculated from the digestion of one-half the precipitate. 



8. Hempstead silt loam. Duplicate 250 gram samples were 

 hydrolyzed for 48 hours. The "humin" was washed and the de- 

 termination carried out as described under mineral soils. The only 

 explanation which occurs for the higher ammonia nitrogen of one 

 hydrolysate is that Sample I must have been heated more strongly 

 during hydrolysis. From unpublished experiments conducted at 

 this Station it has been found that when a pure protein is hydro- 

 lyzed under vigorous boiling, a. greater amount of ammonia nitro- 

 g~en is invariably obtained than when hydrolyzed under slow boil- 

 ing conditions. This observation was made subsequently to my 

 own, so that the importance of the rate of boiling was not known 

 at the time of doing my work. 



Only 25 grams of phosphotungstic acid were added for the 

 precipitation of the bases. After standing the solution gave a 

 further precipitate on addition of more phosphotungstic acid. It 

 was concluded, however, that the organic bases were entirely pre- 

 cipitated, for on washing the precipitate with the phosphotungstic 

 acid wash water no additional precipitate formed. The nitrogen 

 determination gave 0.0011 gram retained by the barium phospho- 

 tungstate. The solution containing the nitrate from the bases was 

 made to 300 cc. volume. 



