92 



BULLETIN No. 145 



[April, 



probably their fertility to its presence since it held in combination, 

 phosphorus, nitrogen, and certain mineral elements. 



Deherain (22) determined the carbon content of soils from 

 plots which had received different treatment. He found that the 

 soils from the plots which had not been manured had lost over 

 50 percent of their carbon. 



Kostytschiff (24) .studied the humus obtained from substances 

 of known origin and which were 'converted into humus under con- 

 trolled conditions. He learned that even with the albuminous sub- 

 stances the carbon was lost more rapidly than the nitrogen, hence 

 the ratio of carbon to nitrogen would be narrower in the resulting 

 humus than in the original material. 



Berthelot and Andre (31) found that 67.1 percent of the total 

 carbon in soils was soluble in dilute alkalis .but that over one-half 

 of this soluble carbon, or 40 percent of the total carbon; was not 

 precipitated from the alkalin solution by the addition of an acid. 



Snyder (37) reported the results obtained by a study of the 

 production and analysis of the humus obtained from such sub- 

 stanees as cow manure, clover, meat scrap, etc., etc., which were 

 converted into humus under known conditions. The carbon 

 content of the humus varied from 41.95 percent in case of the hu- 

 mus produced from cow manure to 57.84 percent in case of the 

 humus produced from cane sugar. 



Hess (45) studied the effect of different systems of treatment 

 on the humus of the soil. He found that the ratios of carbon to 

 nitrogen and nitrogen to humus were not materially effected by the 

 treatment applied. 



Andre (47) studied the action of potassium hydroxid on the 

 carbon compounds of the soil, mould, compost and peat. He de- 

 termined the insoluble and soluble carbon : the latter he separated 

 into two classes; the portion precipitated from alkalin solution by 

 the addition of an acid, and the portion remaining in solution. The 

 results obtained are expressed in Table i. 



TABLE 1. PERCENTAGE OF SOLUBLE AND INSOLUBLE CARBON AND RATIO 

 OF CARBON TO NITROGEN 



