nc have been rather shunned because of the
difficulty in extracting them.

It is thought that our resources of zinc, especially in the West, have
just begun to be developed, and that the supply, even at the present
rate of increase and at present prices, will last many years. However,
with increasing use for the product, we can not be sure of supplies for
more than a generation; and in view of the importance of zinc it becomes
necessary to inquire into its wastes.

In no mineral is the waste more startling than in zinc. In Missouri it
is necessary to leave supporting pillars as in coal mining. This can not
be remedied, as the use of timbers is too expensive, but it causes a
heavy loss. In the West, owing to the expensive treatment and shipment,
much of the low-grade ore is left in the ground. In refining the loss is
enormous, often as much as forty per cent. In order to produce zinc at a
low cost there must be a heavy loss of metal. Better plants and
equipment for refining, and the saving of all refuse for later use will
be necessary if we are to conserve the zinc supply for future
generations.

MISCELLANEOUS

The supplies of many of the materials used in buildings and bridges,
such as stone, gravel, clay, cement and lime are so great that they
appear inexhaustible, and need of care in their use is not so much to be
considered as is their development to take the place of other resources.

In the past they have not been used freely because wooden buildings have
been so much cheaper; but cement, concrete and brick are now
manufactured much more cheaply, on account of improved methods, while
the price of lumber has been increasing rapidly. Within the last ten
years, the value of cement manufactures has increased nearly six times.
In 1900 we used seventy pounds of cement for each person; in 1907, two
hundred and twenty-eight pounds. The value of brick and other products
made from clay has doubled in the same period and is now $160,000,000,
while the value of building-stone quarries is three times as great as it
was ten years ago. There are many reasons why these materials should
take the place of wood; as they are stronger, more durable, do not
require paint, and are so much less liable to loss by fire.

The waste of minerals used in building is due to improper and reckless
methods of taking them from the ground and preparing them for market and
in careless methods in manufacturing.

Of such minerals as quartz, gr