300 AGRICULTURAL EXPERIMENT STATION. [Jan. 



These experiments in general coincide with field and pot 

 experiments as well as with artificial digestion experiments. 

 It is worthy of note that the light sandy soil was most favor- 

 able to the process of nitrification, while the very heavy clay, 

 and especially the sour marshy soil, was decidedly unfavor- 

 able to the action of nitrifying organisms. 



//. Investigations concerning the Value of Leather Refuse 



made at this Station. 



m 



1 . Can Leather he identified in Fertilizer Mixtures ? 



If one were to depend upon the microscope, it would 

 certainly be an impossibility to recognize leather in finely 

 ground fertilizer mixtures. Even if material of a fibrous 

 structure were detected it would be nothing strange, for all 

 flesh presents such a structure. After leather has been sub- 

 mitted to heat or pressure all structure is destroyed. Able 

 microscopists, who have attempted to identify the leather 

 under the microscope, report it an impossibility. 



With chemical reagents one is more successful. At least, 

 tannic or gallic acids, from their well-known reaction with 

 an iron salt, are easily recognized ; and, while one perhaps 

 could not positively declare that the tannic or gallic acids 

 present were derived from leather, it certainly would be 

 highly probable. 



Dr. C. W. Dabney,* when director of the North Carolina 



* North Carolina Experiment Station Bulletin, No. 3, 1883 : Horn, Leather and 

 AVool Waste. 



