1913] S. L. Jodidi 21 



stances, ^. ^r., diamino acids (Kossel's hexon bases)/^ purin^^ bases, 

 and amins.^^ It contains a variety of "neutral" Compounds, e. g., 

 hydrocarbons/^ esters, aldehydes, as well as amphoteric substances 

 like amino acids,^^ etc.^° Moreover, there is very little doubt that 

 the number of definite organic Compounds which can be extracted 

 from " soil organic matter " will be considerably increased within 

 the next few years. 



Mention may be made here of the fact that, of the Compounds 

 found in " soil organic matter," the amino acids and acid amides 

 play a prominent role, for the reason that they are contained in pre- 

 dominant proportions in acid extracts of soils ; and for the further 

 reason that they represent an important source for the production 

 in the soil of ammonia,^^ and hence of nitrates. 



Considering that certain constituents (the ten well known Cle- 

 ments) are absolutely indispensable for plant life, it is easy to un- 

 derstand why humus is called by many the "life of the soil." Not 

 only does it contain most of the elements which are necessary 

 for plant life, like nitrogen, phosphorus, sulfur, etc., but, what is of 

 equally great importance, it affords a means for rendering more of 

 the necessary inorganic elements available. 



The carbon dioxide, nitric acid and sulfuric acid which result 

 through oxidation of the elements carbon, nitrogen and sulfur in 

 humus, are powerful agents for the extraction of indispensable ele- 

 ments (potassium, calcium, magnesium and others) from the rocks, 

 thus Converting rocks and rocky land into fertile arable soil. 



15 Jodidi: Techn. Bul. No. 4 {1909), Mich. Agr. Expt. Station; Research 

 Bul. No. I, Iowa Agr. Expt. Sta. (1911) ; Jodidi and Wells: Research Bul. No. 

 2, Iowa Agr. Expt. Sta. (1911). 



18 Schreiner and Shorey: Jour. Biol. Chem., 8, 385 (1910). 



1'' Shorey: Proc. Eighth Intern. Congr. Appl. Chem., 15, 249 (1912). 



18 Shorey: Proc. Eighth Intern. Congr. Appl. Chem., 15, 248 (1912). 



lö Jodidi: Jour. Amer. Chem. Soc, 32, 396 (1910) ; 33, 1226 (1911) ; 34, 94 

 (1912); Schreiner and Shorey: Jour. Biol. Chem., 8, 381 (1910) ; Robinson: 

 Techn. Bul. No. 7, Mich. Agr. Expt. Sta. (1911) ; Jour. Amer. Chem. Soc, 33, 

 564 (1911). 



20 A good account of the Compounds extracted from soils is contained in 

 Proc. Eighth Intern. Congr. Appl. Chem., 15, 248-250 (1912). 



21 Jodidi, Kellogg and Snyder: Research Bul. No. g, Iowa Agr. Expt. Sta- 

 tion (1912) ; Jodidi: Jour. of the Franklin Institute, 175, 245 (1913) ; Ibid., 175, 

 483 (1913) ; Proc. Eighth Intern. Congr. Appl. Chem., 26, 119 (1912), 



