196 BOARD OF AGRICULTURE. 



which it is not soluble in water, but is soluble in the acids of 

 the soil or in the mechanism of the plant. It is no doubt 

 true that the soluble phosphate of lime does revert after it 

 has been in the soil some length of time. From this a few 

 scientists have reasoned that it is not necessary to dissolve 

 any phosphatic compound in sulphuric acid, and so con- 

 clude that phosphate rock or raw ground bone is just as 

 valuable as that which is dissolved. Such reasoning, how- 

 ever, is opposed to experience and common sense. Forty- 

 seven years of experience si-nce Liebig's time have shown 

 that no mechanical division can be made equal to that pro- 

 duced by the action of the sulphuric acid upon the phosphate 

 of lime. Mill after mill has been invented, process after 

 process tried, for the reduction of phosphates to a condition 

 equal to that produced by chemical means, and yet all, with 

 possibly two exceptions, have been cast aside. 



It is found that bone, treated with steam under high press- 

 ure, will yield a small percentage of reverted phosphate of 

 lime, — never soluble. It is probably true that mixing bone 

 with an alkali and allowing it to heat will render a portion 

 more or less reverted, but never soluble. Steam and alkali, 

 however, have no effect on natural phosphates like South 

 Carolina rock or Canadian apatite. Neither is effective, 

 except when animal matter is present to assist by its decay 

 the process of disintegration. 



It being generally admitted that soluble phosphates be- 

 come partially insoluble after application to the soil, it is 

 of course a very natural question to ask, " What is the need 

 of dissolving them at all ? Will not the soil act upon them 

 if they are finely ground, so as to render them gradnally 

 available?" Doubtless it will if you give it time ; but time 

 is an important element. If you are growing century plants 

 or oak trees, it would not be advisable to apply soluble 

 phosphates ; but these are not the cultivated crops of this 

 section. On or before the 25th of next May, if we live, and 

 the weather and other conditions are favorable, most of us 

 will plant a crop of corn, which not only must be supplied 

 with carbonic acid, oxygen and hydrogen, which it gets from 

 the air and water, but with a large amount of phosphoric 

 acid, from the time it begins to send out little rootlets until 



