6 JOURNAL OF THE 



soluble, insoluble, reverted, and available are not fixed and defi- 

 nite quantities. They are dependent on so many conditions of 

 time, temperature, degree of fineness, quality and quantity of 

 solvent, a«;itation, etc., that it is no matter of wonder that even 

 skillful manipulators vary in their determination. They are the 

 results of methods, and will vary according to the method or the 

 manner of executing the details of the method. But, as has 

 been remarked and as its name implies, the total is all the phos- 

 phoric acid in the material under examination, of whatever kind 

 and in whatever shape or form. It is not what is gotten by a 

 method, but what there is there, and any method, tl erefore, that 

 fails to reach any part or kind of it is not a method for total 

 phosphoric acid. It is sometimes said that discrimination is 

 impracticable, and that all fertilizers should be treated equally 

 and alike. The position is untenable. It might as well be 

 urged that in order not to discriminate the plain soda-lime 

 method for the determination of nitrogen should be used on all 

 fertilizers, those containing nitrates as well as those containing 

 organic nitrogen alone, when every one knows that it is inade- 

 quate in the presence of nitrates. So a total method which is 

 adequate for some kinds of fertilizers, but not for others, cannot 

 be applied to all on the above ground or any other ground, with- 

 out manifest injustice to those fertilizers foi* which the method is 

 inadequate. 



The Association of Official Agricultural Chemists in their 

 official methods (Bulletin 24, United States Department of Agri- 

 culture) give three alternate methods of determining total phos- 

 phoric acid. There is no distinction made between them, no 

 indication that either is belter ada j)ted than the other for any 

 })articular class of fertilizei's. The presumption is, that thry are 

 given as interchangeable and ecpially allowable for all classes of 

 fertilizers, at the pleasure oi* option of the operator. It is the 

 purpose of this article to show that one of them, at least, is 

 entirely inadequate for fertilizers that contain cotton seed meal, 

 and that any (;h(Muist who uses this method on such fertilizers is 

 in almost certain danger of doing these fertilizers a great injustice. 



