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BULLETIN OF THE BUSSEY INSTITUTION. by 
while to calculate in any of the substances analyzed, are phosphoric 
acid and nitrogen, and it is therefore the money worth of these two 
ingredients which is to be estimated. 
In the spring of 1872 insoluble phosphoric acid could be bought in 
Boston at five cents per pound, in the form of waste bone-black. The 
price of this substance, containing thirty per cent of phosphoric acid, 
as stated above in analysis No. XVI., was one and a half cents per 
pound. 
Bone-ash from South America containing seventy per cent of pure 
bone-phosphate of lime is sold in London at from £6 15s. to £7 the 
long ton, equivalent (1872-73) to about $ 32 in our money per ton of 
2,000 pounds containing 644 pounds of phosphoric acid. Since it is fair 
to suppose that bone-ash could be imported into Boston about as cheaply 
as it can be carried to London, it may be assumed that the pound of 
insoluble phosphoric acid can be had in this form also for five cents. 
As contained in bone-meal, insoluble phosphoric acid has been. 
valued by Professor Johnson* and others at six cents per pound. 
It is believed by many chemists that, pound for pound, the phos- 
phoric acid in bone-meal is worth more to the farmer than that in 
bone-ash or in bone-black. However that may be, the last estimate 
(six cents per pound) has the advantage of being more generally ap- 
plicable than either of the others. Since bone-meal may be procured 
in almost any locality, a valuation of phosphoric acid based upon the 
cost of this material will manifestly be of a less local and more general 
character,than the estimates based upon bone-black or bone-ash, which 
are to be had at cheap rates only in the vicinity of sugar-refineries or 
of seaports. 
It appears then that insoluble phosphoric acid may be reckoned as 
worth from five to six cents per pound. 
Sixteen and a quarter cents per pound may be allowed for soluble 
phosphoric acid, this being the valuation adopted by Professor John- 
son. It is a liberal allowance in view of the strong probability that 
soluble phosphoric acid can be imported from Europe at a lower rate. 
Thirty cents per pound may be allowed for nztrogen in the form of 
ammonium compounds and for that in blood, this estimate being some- 
what higher than the price.at which the pound of active nitrogen can 
usually be bought either in the form of guano or of nitrate of soda. 
* Connecticut Agricultural Reports for 1870. 
VOL. I. 3 
