34 



AGRICULTURE. 



[CH. 



moistening them with water, and then covering them 

 up with sawdust or fine earth. In a short time these 

 bones became very warm, and when they had been so 

 treated for a few weeks they were found to have be- 

 come softened, and when used upon the land they 

 quickly broke up and mingled with the soil. Hence 

 they were more quickly ready for supplying phosphate 

 of lime to the plant. 



64. It is very desirable that you should be acquainted 

 with the changes that took place in bones so employed, 

 and observe the chemical changes which prepared 

 them for absorption into circulation as plant food. In 

 order that you may fully realize these changes, you 

 must understand that there are at least three distinct 

 forms of phosphate of lime, and their composi- 

 tion may be familiarly represented in the following 

 manner 



You will observe the connection between their names 

 and their composition. The tri- calcic phosphate, 

 or, as the name signifies, three-lime phosphate has 

 three equivalents of lime combined with one 

 equivalent of phosphoric acid. The bi-calcic phos- 

 phate, or two -lime phosphate, has only two equiva- 

 lents of lime with one equivalent of phosphoric acid, 

 and one equivalent of water takes the place of the one 

 equivalent of lime, in which it is deficient. The 

 mono-calcic phosphate, or one-lime phosphate, 

 has only one equivalent of lime combined with 

 one equivalent of phosphoric acid, but it has two 



