244 HA.NDT-BOOK OF HUSBANDRY. 



of Professor Johnson, measured under the microscope the size of 

 the particles of the finest bone-dust, and of the phosphate of lime 

 which had passed through the process described above. He found 

 that the smallest particles of bone-dust would not average less 

 than one one-hundredth of an inch in diameter, while the particles 

 of the prepared phosphate measured only one twenty-three-thou- 

 sandth of an inch in diameter. If, as is probably the case, the 

 degree of solubility of both is the same, the amount of surface 

 which the finer article exposes to the solvent action of water is 

 so infinitely greater than that of the former, that the total amount 

 which may be dissolved by the action of a given amount of water 

 in a given time must be almost inestimably greater; and we 

 find in practice that the finest phosphate of lime that it is pos- 

 sible to produce by the burning of bone, is very much less rapid 

 in its action than is that which results from the chemical processes 

 in use in the manufacture of commercial superphosphate. 



Probably it makes but little difference what sort of phosphate 

 of lime is used in the manufacture of a superphosphate, — whether 

 the original substance be the earthy matter of bones, the phos- 

 phatic deposits of South Carolina, or what is known as Colum- 

 bian guano ; for, probably, the chemical action in the use of each 

 will be the same, and the same quality of superphosphate, and of 

 the phosphate which is formed on the application of this to the 

 soil, will result. 



Many directions are given for the manufacture of superphos- 

 phates on the farm by the decomposition and preparation of bones. 

 The best of these is, perhaps, the following, which is given by 

 Dr. James R. Nichols, in his " Chemistry of the Farm and the 

 Sea " : — 



" Take a common sound molasses cask ; divide in the middle 

 " with a saw ; into one-half of this place half a barrel of finely- 

 *' ground bone, and moisten it with two buckets of water, using 

 " a hoe in mixing. Have ready a carboy of vitriol, and a stone 

 "pitcher holding one gallon. Turn out this full of the acid, and 

 " gradually add it to the bone, constantly stirring. As soon as 

 " effervescence subsides, fill it (the pitcher) again with acid, and 



