upils write with a pencil made of soft gray schist.
This application, which is capable of rendering services in a host of
details of domestic economy, has given rise to artificial slates,
which, made by a process of moulding a composition analogous to
cardboard pulp, present the same advantages as ordinary slate, while
being much lighter.

Along about 1834 an Englishman of the name of Magnus utilized the
property that slate possesses of taking a fine polish in the invention
of what are called enameled slates. These products are used especially
in the manufacture of table tops, mantelpieces, altars, etc. They very
closely imitate the most expensive marbles, and their properties,
along with their low price, have been the cause of their introduction
into the houses of all classes of the English population, as well as
into those of entire Europe and America.

The ease with which slate is obtained in slabs of large dimensions has
greatly contributed in recent times toward still further increasing
its applications. One of the first of such applications was the
substitution of it in urinals for cast iron plates, which very rapidly
oxidize and become impregnated with nauseous odors that necessitate a
frequent cleaning and constitute a permanent source of infection.

For a few years past, too, slate has been used, in the manufacture of
vats designed for breweries. These vats, of which we show in the
accompanying figure a model of the installation employed in the Ivry
Brewery, are each 61/2 feet square and 5 feet in depth. For leading the
beer, which, upon coming from the brewing apparatus, must rest for a
few days, they are connected by a system of pipes. A second system of
pipes, which in our figure is seen running along the cellar vault,
serves as a cooling apparatus and maintains a temperature of 5 deg. C.
above zero in the vats arranged in two rows to the right and left.

The details or even a simple enumeration of the new applications of
slate would, in order to be anywhere nearly complete, necessitate a
lengthy article. Let us say in conclusion that slate is substituted
for wood, which is too easily attackable, and for marble, which is
much more costly, in our laboratories and amphitheaters and everywhere
where the manipulation and stay of easily corrupted liquids and solids
require the greatest cleanliness in the material of construction.--La
Science en Famille.

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