362 BOARD OF AGEICULTURE. 



ton, a finer grade at $35, and the finest ground variety at 

 $40. Fifty dollars per ton is, in our section of the country, 

 the usual price charged to farmers. The farmer ought to 

 insist upon getting the bones ground as fine as possible. I 

 have tested bone-meal of L. B. Darling, of Pawtucket, R. I., 

 and found it of a good average composition ; its mechanical 

 condition might have been better. 



A genuine well-ground bone-meal is the safest and most 

 efiicient form among the natural phosphates. Prof. Volcker 

 and others prefer it, even in many instances as more reliable, 

 to most of our ordinary commercial superphosphates. 



Those who have paid for years a closer attention to the 

 trade in bone-meal, report of adulterations with sand, coal- 

 ash, gypsum, sawdust, marl, etc., in some instances as high as 

 34 per cent. 



Bone-Black Waste. 



The refuse bone-black from sugar-houses is sold at Bos- 

 ton at from $20 to $25 per ton to fertilizer manufacturers. 

 It contains from 72 to 75 per cent, of bone phosphate in a 

 very insoluble form, and ought, on that account, not to be 

 recommended for direct application to the soil. It deserves, 

 however, a particular recommendation for the manufacture of 

 superphosphate . 



I have tested samples of bone-waste, from Boston and else- 

 where, and find them of a fair composition. Allowing 32 per 

 cent, of phosphoric acid as a low percentage, we find its com- 

 mercial retail value, according to the adopted standard, viz., 

 six cents for each pound of insoluble phosphoric acid, equal 

 to $38.47. 



Superphosphates and Ammoniated Superphosphates. 



This class of compounds represents by far the largest por- 

 tion of our home-made commercial fertilizers. The phosphoric 

 acid which they contain is, as a general rule, obtained either 

 from raw and boiled bones, or from the waste of bone-black, 

 or from two or three mineral phosphates. 



I am informed, by a good authority, that about four-fifths of 

 the superphosphates at present manufactured within the United 

 States, are produced from the South Carolina and Navassa 

 Island phosphates. They fill our markets, and are appar- 



