BULLETIN OF THE BUSSEY INSTITUTION. 385 
potash salt. It is noteworthy in this connection that the price of salt- 
petre itself (nitrate of potash) has undergone a great reduction of late 
years, thanks to the production of enormous quantities of cheap chloride 
of potassium at Stassfurt, and to the facility with which saltpetre may 
be made from that salt and the nitrate of soda from Peru. Thus, at the 
present time (November, 1875), crude saltpetre is quoted at 5% to 64 
cents gold, or about seven cents, currency, per pound in Boston; and, 
although this price is still too high to admit of the saltpetre itself being 
used as a manure, it is nevertheless evident that, as prices now go, 
the saltpetre waste of the gunpowder makers will henceforth probably 
be more valuable as a fertilizer than it was in the days when saltpetre 
was comparatively speaking a costly salt. With saltpetre as cheap as 
it now is, a refiner operating on the small scale could hardly afford to 
be as careful to save saltpetre in his processes of crystallization as he 
once was. He would be justified in leaving a considerably larger pro- 
portion of potash and of nitric acid in the “waste” nowadays than 
formerly. 
That saltpetre itself, at the price just stated, cannot economically be 
used as manure will appear from the following considerations. If we 
admit that the crude salt contains 90% of pure nitrate of potash, as 
it often very nearly does, then every hundred pounds of the crude 
article would represent 42 lbs. of real potash and nearly 124 lbs. of 
nitrogen. But real potash can be got at five cents per pound at the 
present time in the form of muriate of potash, and the nitrogen in 
nitrate of soda costs about 20 cents* per pound, if we allow 15% of 
nitrogen in the crude nitrate of soda, which can be bought at pres- 
ent for a trifle more than three cents per pound currency. Hence 
it appears that the intrinsic value to the farmer of a hundred pounds 
of the crude saltpetre is only $4.60, while it would cost him $7.00. 
The beneficial action both of saltpetre-waste and of saltpetre itself 
(nitrate of potash) on soils in this vicinity has been well illustrated by 
* While nitrogen in the form of nitrate of soda can be obtained at so cheap a 
rate, the farmer should be upon his guard not to pay a disproportionate price for 
nitrogen that he may wish to buy in some otherform. While the price of nitrate 
of soda is thus reduced, the price of various other nitrogenous manures, such as 
meat-dust and the dried refuse of slaughter-houses, should by good rights fall also. 
It is to be observed that the calculations of the values of certain nitrogenous 
manures given on pages 17, 18 of this Bulletin were based upon a much higher 
value for the pound of nitrogen than can be admitted at the present time. 
VOL. I. 49 
