134 SOILS: PROPERTIES AND MANAGEMENT 



1. Nitric nitrogen 3. Diamino aeids 



2. Ammoniacal nitrogen 4. Acid amides 



5. Monamino acids 



The two latter constituents were found to make up the 

 bulk of the organic nitrogen, but quantitative determina- 

 tions proved uncertain. These compounds produced 

 ammonia readily, the rate depending on their chemical 

 structure. 



92. The work of Oswald Schreiner. Of the chemists 

 who have been most active and most successful, Schreiner l 

 deserves especial mention. Our present knowledge of the 

 chemical constitution of the organic matter of the soil is 

 very largely due to his efforts. While he realized that 

 the isolation of specific compounds from the soil was likely 

 to present insurmountable problems, and that the iden- 

 tification of such compounds after they were obtained 

 might be very difficult, he undertook a systematic ex- 

 traction of the soil. As a result of several years of work 

 he was able to isolate and identify a number of com- 

 pounds. The complexity and varied character of these 

 compounds is revealed by the following list of the more 

 important bodies isolated : 



LIST OF COMPOUNDS ISOLATED FROM SOIL ORGANIC 

 MATTER BY SCHREINER, SHOREY, SKINNER, REED, 

 AND OTHERS, OF THE U. S. BUREAU OF SOILS 



Hentriacontane, C 3 iH 6 4 Picoline carboxylic acid, 



Dihydroxystearic acid, C 7 H 7 O 2 N 



Ci 8 H 3 6O 4 Histidine, 



1 Schreiner, O., and Shorey, E. C. The Isolation of Harm- 

 ful Organic Substances from Soils. U. S. D. A., Bur. Soils, 

 Bui. 53, 1909 ; also, Buls. 47, 70, 74, 77, 80, 83, 87, 88, and 90. 



