38 



mined on the filter and -contents by the Kjeldahl method and listed 

 as "basic N." The filtrate from the above precipitate was con- 

 centrated and made to 300 cc. volume. Duplicate determinations 

 were made on 100 cc. portions, and the total nitrogen listed as 

 nitrogen in the filtrate from the "bases." 



4. The determination of nitrogen. Nitrogen was determined 

 on the soils and soil extracts in the usual manner, using 25-35 cc. 

 H.,SO 4 , 10 gm. K 2 SO 4 , and a crystal of CuSO 4 . All titrations were 

 made with N/14 acid and alkali so that the figures obtained repre- 

 sented milligrams of nitrogen without necessitating a calculation. 



D. The Analytical Data. 



The essential data which have already been published on the 

 soils studied are shown in Table I. 



Table I. Certain analytical data for the soils used in this paper. 

 Data of Gortncr (1$16 a). 



1. Analysis of "fibrin from blood" hydrolyzed in the presence 

 of 100 grams ignited subsoil. This analysis was conducted in order 

 to ascertain if possible the effect of soil minerals upon the hydro- 

 lysis of a pure protein. Fibrin w r as selected because it was from 

 a sample already analyzed (Gortner 1916 c). The subsoil was first 

 ignited to redness in a muffle furnace for an hour, in order to drive 

 off all the organic matter, and subsequently cooled in a desiccator. 



Duplicate portions of five grams fibrin and 100 grams ignited 

 subsoil were hydrolyzed in the presence of an excess of hydrochlo- 

 ric acid. Upon the application of heat, fumes of hydrogen chloride 

 were evolved for some time. The analysis was conducted like 

 that of the mineral soils, excepting that a 600 cc. aliquot was used 

 for the analysis, this amount of solution being equivalent to three 

 grams of fibrin. After making the ammonia determination the 

 humin precipitate was washed by decantation in the usual man- 

 ner and the filtrate made to 250 cc. volume. The first wash solu- 



