Economy of Nitrogen. 
*57 
1878.] 
of the soil of India, and lessened the crop-producing power 
of the world in general just as much as did the nitre-beds 
of Europe. 
It is true that at the present day the great bulk of the 
saltpetre used, whether in the manufacture of gunpowder or 
in other arts, is obtained from a different source, — the depo- 
sits of nitrate of soda found on certain parts of the western 
coast of South America. From these vast deposits more 
than 4,000,000 cwts. are yearly exported to different parts of 
the world ; yet even these beds are supposed to have been 
originally formed by the decomposition of nitrogenous or- 
ganic matter, and though large they are by no means 
incapable of exhaustion. So long as we take combined 
nitrogen and set it at liberty then, no matter whence our 
supply is obtained, the ultimate result must be complete 
sterility. 
The manufacture of gunpowder involves another kind of 
waste, which is more conspicuous in the present state of 
the trade than it was formerly. The nitrate of soda im- 
ported from South America, unlike the nitrate of potash, 
has the property of absorbing moisture from the air, and is 
hence utterly unfit for the preparation of gunpowder. 
Before it can be used for any such purpose it must be con- 
verted into common saltpetre by appropriate treatment with 
some salt of potash. Now, most unfortunately, potash — 
just like phosphorus and like combined nitrogen — is an 
important constituent of the food of plants, and we can 
only procure it by the old sin of robbing our crops. For- 
merly the salts of potash were obtained by burning timber 
to ashes and lixiviating the residue. Next, the salts left in 
the preparation of beet-root sugar were employed. In either 
case the substantial result was the same : unless we can 
show that pine-trees or beet-plants have the power of cre- 
ating potash out of nothing, or out of some other elementary 
body, we must confess that they obtain it from the soil, and 
that the soil must ultimately become exhausted. But pot- 
ash compounds are now obtained by mining, at Stassfurt 
and elsewhere ? Granted, yet the supply — like that of 
nitrate of soda in Atacama — is not infinite. 
The gunpowder manufacturers, or those who prepare 
their materials, compete with the farmer for the one and 
the other of these products, raising the price and hastening 
the day of exhaustion. As regards potash, however, the 
waste is of a less fatal character than the expenditure of 
combined nitrogen. Gunpowder, indeed, contains the 
