I 



ELISHA MITCHP:I.L SCIENTIFIC SOCIETY. 7 



The method referred to is the second of the three given, namely: 

 "Solution in thirty c. c. of concentrated nitri(; acid with a small 

 quantity of hydrochloric acid." Tlie writer has not extended 

 his investigation, except imperfectly, to the other two methods. 

 It is only with this one, as applied to cotton seed fertilizers, that 

 this article has to do. 



Cotton seed fertilizers are comparatively unknown in the 

 North. It seems, therefore, that the Southern members of the 

 A. O. A. C. must not have been very wide-awake to the interests 

 of a class of fertilizer manufacturers peculiar to their own sec- 

 tion of country when they failed to have attached to this method, 

 at the time when it was adopted l>y their Association as one of 

 three alternate methods, the limitation "not applicable to fer- 

 tilizers containing cotton seed meal." 



Cotton seed meal is readily and entirely soluble in either 

 " nitric acid with a small quanity of hydrochloric acid" or in 

 nitric acid alone. But such a solution does not give up its j^hos- 

 phoric acid to molybdic solution. It would appear that certain 

 nitro-organic compounds are formed which prevent the phos- 

 phoric acid in the solution from being yielded up to the molybdic 

 precipitant. Whether this is effected by in some way rendering 

 the menstruum a solvent for the phospho-molybdate of ammonia 

 that ought to be formed, or, by holding the phosphoric acid in 

 check, serves thus to prevent such a combination, is not clear. 

 But the fact remains. The attention of the writer was first for- 

 cibly directed to it when a sample of cotton seed meal was sub- 

 mitted to him for a determination of the available phosphoric 

 acid it contained. A nitric acid solution of two grams of it was 

 made (using also a little hydrochloric acid), the solution being 

 perfect, and a total phosphoric acid percentage of 0.51 found. 

 A duplicate made in the same way yielded 0.54 percent. Being 

 convinced that there was much more phosphoric a<'id in the meal 

 than this, and recalling that a short time previously a gentleman 

 had remarked that a friend of his had found materially more 

 phosphoric acid in the ash of cotton seed meal than by acid solu- 

 tion, two grams of the meal were ignited to perfect ash, the ash 



