her steelworks.
When phosphorus occurs in iron ore, even in minute amounts, it makes the
steel brittle. Much of the iron ores of Alsace-Lorraine were formerly
considered unworkable because of this impurity, but shortly after
Germany took these provinces from France in 1871 a method was discovered
by two British metallurgists, Thomas and Gilchrist, by which the
phosphorus is removed from the iron in the process of converting it into
steel. This consists in lining the crucible or converter with lime and
magnesia, which takes up the phosphorus from the melted iron. This slag
lining, now rich in phosphates, can be taken out and ground up for
fertilizer. So the phosphorus which used to be a detriment is now an
additional source of profit and this British invention has enabled
Germany to make use of the territory she stole from France to outstrip
England in the steel business. In 1910 Germany produced 2,000,000 tons
of Thomas slag while only 160,000 tons were produced in the United
Kingdom. The open hearth process now chiefly used in the United States
gives an acid instead of a basic phosphate slag, not suitable as a
fertilizer. The iron ore of America, with the exception of some of the
southern ores, carries so small a percentage of phosphorus as to make a
basic process inadvisable.

Recently the Germans have been experimenting with a combined fertilizer,
Schroeder's potassium phosphate, which is said to be as good as Thomas
slag for phosphates and as good as Stassfurt salts for potash. The
American Cyanamid Company is just putting out a similar product,
"Ammo-Phos," in which the ammonia can be varied from thirteen to twenty
per cent. and the phosphoric acid from twenty to forty-seven per cent.
so as to give the proportions desired for any crop. We have then the
possibility of getting the three essential plant foods altogether in
one compound with the elimination of most of the extraneous elements
such as lime and magnesia, chlorids and sulfates.

For the last three hundred years the American people have been living on
the unearned increment of the unoccupied land. But now that all our land
has been staked out in homesteads and we cannot turn to new soil when we
have used up the old, we must learn, as the older races have learned,
how to keep up the supply of plant food. Only in this way can our
population increase and prosper. As we have seen, the phosphate question
need not bother us and we can see our way clear toward so