BULLETIN OF THE BUSSEY INSTITUTION. 185 
No. 9.— On the Valuation of the Soluble Phosphorie Acid in 
Superphosphate of Lime. By F. H. Storer, Professor of 
Agricultural Chemistry. 
In calculating the value of a superphosphate from the consumer’s 
point of view, it has hitherto been difficult to determine, even approx- 
imately, what price should be allowed per pound in this vicinity for 
the soluble phosphoric acid. 
In the nature of things, it is less easy to form a just estimate of the aver- 
age value of the constituents ofa manufactured article like superphosphate 
of lime, than of those of a waste product, like the siftings of bone-black, 
or of a raw material like bone-ash. The prices of the substances last 
named are controlled by the simplest laws of trade, and they are conse- 
quently, comparatively speaking, definite and well known, and subject to 
no great fluctuations. But the price and composition of bone-ash, and 
of spent bone-black, having been determined, the price of the insoluble 
phosphoric acid contained in these materials follows as a matter of 
course, as has been set forth on page 17 of this “ Bulletin.” So, too, the 
price per pound that the farmer must pay at the present time for 
potash rests directly upon a firm and definite basis; viz., the price 
of “muriate of potash” imported from Germany.* But with respect 
* In January-February, 1874, muriate of potash, containing 80% of the 
pure salt (KCl), was sold in Boston at $55.00 currency per ton, a price that 
would be equivalent to about 54 cents per pound, for real potash K,O. 
It is to be hoped that the chemical manufacturers of New England will find 
their advantage in employing the German muriate of potash for making muri- 
atic acid, in place of the common salt now used for that purpose. The residual 
“salt cake,” —a somewhat acid sulphate of soda, — that results from the present 
system of manufacture, is a substance that is often hard to dispose of in this 
region. It has very little agricultural value. But for sulphate of potash, of 
high grade, such as would result from the manufacture of muriatic acid from 
the better sorts of the German muriate of potash, there should be a well-nigh 
unlimited demand for agricultural purposes. 
There must always be a certain afvantage in transporting the muriate rather 
than the sulphate of potash from Stassfurt, as Professor Johnson has already 
remarked, because of the somewhat lower equivalent weight of the muriate. 
But, on the other hand, sulphate of potash is to be preferred to the muriate as a 
fertilizer on several accounts.. The sulphate has some useful qualities of its 
own, and it is rather less likely than the muriate to do harm when used unin- 
telligently. 
VOL I. 24 
