320 TALKS ON MANURES. 



" And," said the Deacon, " after it is converted into superphos- 

 phate, the same ton of bones is worth $72.58. It thus appears that 

 you pay $26.42 per ton for simply making the phosphoric acid in 

 a ton of bones soluble. Is'nt it paying a little too much for the 

 whistle ? " 



"Possibly such is the case," said I, "and in point of fact, I 

 think bone-dust, especially from steamed or boiled bones, can be 

 used with more economy in its natural state than in the form of 

 superphosphate." 



Superphosphate can be made more economically from mineral 

 phosphates than from bones the nitrogen, if desired, being sup- 

 plied from fish-scrap or from some other cheap source of nitrogen. 



But for my own use I would prefer to buy a good article of 

 superphosphate of lime, containing no nitrogen, provided it can 

 be obtained cheap enough. I would buy the animoniacal, or nitro- 

 genous manure separately, and do my own mixing unless the 

 mixture could be bought at a less cost than the same weight of 

 soluble phosphoric acid, and available nitrogen could be obtained 

 separately. 



A pure superphosphate and by pure I mean a superphosphate 

 containing no nitrogen can be drilled in with the seed without 

 injury, but I should be a little afraid of drilling in some of the 

 ammoniacal or nitrogenous superphosphates with small seeds. 



And then, again, the "nitrogen" in a superphosphate mixture 

 may be in the form of nitric acid, or sulphate of ammonia, in one 

 case, or, in another case, in the form of hair, woollen rags, hide, 

 or leather. It is far more valuable as nitric acid or ammonia, 

 because it will act quicker^ and if I wanted hair, woollen rags, 

 horn-shavings, etc., I would prefer to have them separate from 

 the superphosphate. 



CHAPTER XXXVIII. 

 SPECIAL MANURES. 



Twenty-five to thirty years ago, much was said in regard to spe- 

 cial manures. Fertilizers were prepared for the different crops with 

 special reference to the composition of the plants. 



"But it was known then, as now," said the Doctor, " that all 

 our agricultural plants were composed of the same elements." 



" True, but what was claimed was this : Some crops contain, for 



