EXPERIMENT STATION. 27 



$8.92, in 766, $11.74, in 779, $15.00. If reverted and insoluble 

 phosphoric acid are valued at 9c. and 6c. per pound, the cost of 

 soluble phosphoric acid will be $8.67, $10.40 and $13.46 per 100 

 pounds respectively. If we add $2.00 to the cost of 735, to cover 

 freight from New York, the hundred pounds of soluble phosphoric 

 acid in it would cost $9.44 without takinaj account of the reverted 



» 



and insoluble, or $9.18 making allowance for these. 



It is evident, then, that soluble phosphoric acid can be bought 

 without difficulty at retail for less than the present Station valua- 

 tion, $12.50 per 100 j^ounds. 



799 is a sample of "Dissolved Bone Black," containing origi- 

 nally not far from 15 per cent, of soluble phosphoric acid, which 

 has been treated with lime to " revert" the phosphoric acid for 

 a particular use. It was sent to the Station for examination by 

 Prof. H. P. Armsby of the Storrs Agricultural School. The 

 analysis is as follows : 



Soluble phosphoric acid, none 



Reverted phosphoric acid, _ 10.14 



Insoluble phosphoric acid, .89 



Wood ashes, leached or unleached, will revert superphosphates 

 in the same way and the two should not be mixed if an applica- 

 tion of soluble phosphate is desired. 



In some sections of the country, purchasers much prefer to buy 

 superphosphates which are dark colored or black. If there is 

 any reason in such a whim it probably lies in the belief that such 

 goods contain bone-black and that a superphosphate made from 

 that material is more apt to be of high grade. The addition of a 

 very little lampblack in the manufacture is a not uncommon prac- 

 tice, to gratify this prejudice. 



Nitrogenous, (Ammoniated) Superphosphates and Guanos. 



This class includes all those commercial fertilizers — excepting 

 the Special Fertilizers or " Formulas" to be noticed further on, — 

 which contain or are claimed to contain any considerable amount 

 of soluble phosphoric acid together with nitrogen. Potash is also 

 found in most of them. Forty-nine samj^les of these goods 

 have been tested. Sixteen were for private parties. The results 

 of the other thirty-three analyses will be found tabulated on 

 pages 28 to 31. 18 are called by the manufacturers, "Phos- 



