MINERAL INDUSTRIES OF THE UNITED STATES FERTILIZERS. 9 
setback because of the strong counter demand for sulphuric acid 
for use in making munitions, raising its price and in turn inducing 
curtailment in output of phosphate rock. 
The coming of peace will undoubtedly rehabilitate the phosphate- 
rock industry, and will probably bring such increased demands for 
its product as will rapidly advance its output. The industry may be 
expected to introduce more efficient methods of mining and han- 
dling the rock, in place of the wasteful procedure still followed in 
many localities, while it should solve the problem of using ma- 
terial of lower grade than practicable under present practice, so as 
to extend the life of the deposits. 
Phosphate rock in the crude condition is not suitable for fertilizer 
purposes, even if finely ground, because its valuable constituent is 
bound up in a relatively insoluble form. Hence the crude material 
is treated with about an equal amount of sulphuric acid, which pro- 
duces a substance called acid phosphate, in which nearly all the phos- 
phorus has been changed to a form suitable for plant food. The fer- 
tilizer industry therefore is closely associated with the manufacture 
of sulphuric acid, consuming indeed just about half of the several mil- 
lion tons of this material made each year, the rest being utilized 
In a hundred and one other industries; for sulphuric acid is one of 
the most widely used of chemical substances. 
The need of large quantities of sulphuric acid gives us one key to 
the localization of the fertilizer industry, since most of the acid used 
for fertilizer purposes is made from pyrite, a sulphur-bearing mineral, 
brought in bulk by return bound Mediterranean freighters, which 
stop at the port of Huelva in Spain and take on as ballast this min- 
eral, mined cheaply in the great mines of Rio Tinto in that country. 
Another reason for the concentration of the fertilizer industry in 
the southeastern States is, of course, the fact that the soils there are 
lean and they also have been long under cultivation and are drained 
of their plant food. 
At the South Atlantic ports, therefore, the pyrite and phosphate 
rock find their cheapest juncture, and here are the principal plants 
which roast the pyrite and manufacture its sulphur fumes by a cum- 
bersome process into the strong acid needed to treat the phosphate 
rock. It is the resultant acid phosphate to which potash and nitro- 
gen compounds are then added to produce the complete commercial 
fertilizer. 
The cutting off, in part, of the supplies of Spanish pyrite by the 
unrestricted submarine warfare of 1917 has considerably upset the 
fertilizer industry by endangering its sulphuric acid source; and 
this condition has led to a limited development of some of the numer- 
ous small pyrite and pyrrhotite deposits of the Eastern States, never 
before able to compete with the Spanish pyrite. It has also directed 
