536 AGRICULTURE. 



be removed, and this is called "reverted." The residue, which 

 can only be dissolved out by acid, is called insoluble. 



But what is the character of the phosphate soluble in solution 

 of ammonium citrate ? No chemist is able to say. It is certain 

 that some portion of it is the tricalcic, so called "insoluble" ; 

 the quantity of which taken up will vary, and depends largely 

 upon the fineness of the grinding, and the length of time the 

 material is exposed to the solvent ; and also to some extent 

 upon the relative volume of the phosphate and the ammonium 

 citrate solution. All that can be said is that the " reverted " 

 phosphoric acid is that which is dissolved out of the fertilizer 

 by the ammonium citrate solution. That this determination, if 

 correctly made, is without the importance attached to it is cer- 

 tain. The practice of English analysts ignores this determina- 

 tion, and in their analyses are reported only phosphoric acid 

 soluble in water, and insoluble in water. 



In the case of nitrogen, the analytical practice is, to reduce 

 all forms of it to ammonia, by incineration of a sample of the 

 fertilizer in a combustion tube, along with a mixture of caustic 

 soda and lime ; to estimate this ammonia, and calculate the 

 nitrogen from the ammonia. This process wholly fails to dis- 

 criminate between the different materials yielding this ammonia, 

 all being classed under one head and subjected to one valuation, 

 which is based upon the cost of the highest priced and most 

 valuable ammoniating materials found in the market. So the 

 manufacturer is invited to cheat the farmer, under the protect- 

 ing panoply of the law, and the indorsement of a defective 

 and crude analysis. He is invited to " ammoniate " his goods 

 with cheap and worthless trash, like parched leather scrap, 

 which yields ammonia freely to the analytical process, but does 

 the crop no good. It places his goods on an equality with those 

 ammoniated with valuable and costly material, such as steam- 

 dried blood. This proceeding misleads and deceives every one 

 concerned, and does so with the solemn sanction of the law. It 

 is high time that there should be an end of it. It is not within 

 the power of any chemist to furnish the data upon which the 

 cost of the materials in any fertilizer can be computed with any 

 approach to certainty or accuracy. 



With regard to the potash, the tendency has been to exagger- 



