GENERAL REMARKS. 193 



tries have set their valuations lower than we 

 have done. 



It is possible that manufacturers may object 

 to our allowing them nothing for the insoluble 

 portion of the phosphoric acid contained in their 

 so-called superphosphates. But we have shown 

 by the best authorities, that phosphoric acid as 

 contained in mineral phosphate (the chief in- 

 gredient in their phosphates), or even in bones, 

 is not available as plant food for many years, 

 ten, twenty or more, and the statements of the 

 manufacturers themselves on this subject show 

 that they are right in theory, if not in practice. 

 The most limited knowledge of finance will show 

 that no value should be assigned to it, because 

 if it takes only 10 years to make it available as 

 plant food, the interest would amount to as 

 much as the purchase money; and if it takes 

 15 years to make it available, the interest with 

 the purchase money amounts to more than the 

 value of phosphoric acid in soluble form. Be- 

 sides, no farmer would knowingly purchase a 

 fertilizer that requires 10 to 20 years to give 

 him a return for his money. The loss by the 

 use of such a manure is not confined to the loss 

 of the interest on the purchase money, but, in 

 addition, the farmer loses his time and the 

 profitable use of his land, which of itself involves 

 many other losses. Independent of all this, such 



