Evening star. [volume] (Washington, D.C.) 1854-1972, 1908-06-28

where to seek them, and in what places they are
obtainable of best quality.
Sand is required too for other building purposes,
particularly in the making of mortar 1t should be
sharp sand, because sand with rounded grains does
not hang together we'll Beach sand for this
reason is not first rate, lnasmuch as most of its
grains rounded, though it has the advantage of
purity. Sharp sand has been der we'd comparatively
recently from granite rocks, which are half quartz,
and is dug usually out of pits where 1t has been
deposited by streams.
Another purpose for which sand is needed is the
growing industry. These bricks which cost three
to four dollars thousand, better than most
pressed bricks at eight dollars They do not
absorb moisture, and are almost waterproof; hence
walls built of them are dry. Furthermore they
be made of any color desired, red, pink, blue, yell
low, green, cream tint, or what not. Iron oxids
and other mineral ingredients in small proportions
employed to color them Coarse sand furnishes
the body of this kind of brick its particles being
locked together with fluid mixture composed of
fine sand and unslaked lime The baking is done
not in kilns, but by superheated steam in ovens.
One OF the most important uses OF concrete is IN
the making OF artificial stone payements Such
stone and much more durable. They can be laid
in larger slabs than can very we'll be quarred, and
often resort is had to the ingenious expedient of
growing them, SO that they may expand with heat
and contract with cold without breaking. 1t is
matter of common and familiar observation that
slabs cut from rock soon crack and 60 to pieces
The artificial stone is more uniform in structure
than the natural kind, and on this account is less
likely to suffer from cracking.
To Study Various Gays
THE Geological Survey will study pottery clays
and tile cays obtained from various localities.
This will be only incidental, however Of much
importance will be the testing of brick clays
and the mapping of available deposits of them in
the neighborhood Of cities. New York obtains some
of its finest brick ciays from Haverstraw. Large
quantities of such clays accessible Chicago.
and both Philadelphia and Baltimore are famous
for their cays. Areas formerly very productive
are nearly worked out, else built over and the
experts purpose to point out fresh Ones
Another important building material is gypsum,
the substance which in its commercial form, ground
to fine POWDER is known as plaster of paris Its
common is for wall plaster. The palaces
of the famous White City at the Chicago Exposition
built of gypsum, which had all the beauty of
marble But while admirable for such a tenn
porary purpose, it will not endure exposure to
weather for long period, and its employment is
ordinarily restricted to inside work. Nodded in
effects as for example, for the lining of the superb
dome of the Congressional Library at Washington.
Another feature of the task undertaken will be
the study of rocks in the vicinity of cities, with
view to finding out which of them most available
for building purposes. No attempt will be made
to quarry the stone; but it will be judged where
with a microscope. incidentally, building stones
that now being quarried commercially will be
tested for their crushing strength their ability to
withstand weather, and other qualities.
The principal building stones granite, marble,
and sandstone. The supply of granite comes mostly
from Massachusetts, and Maine, while the most i'm
Vermont and Tennessee. Sandstones are widely
distributed Chicago gets most of its light colored
sandstone-a material that has become very popu-
lar within recent years-from Ohio. The brown
sandstone of which New York is largely built
comes from the Connecticut Valley and from New
Jersey, where immense quantities of it available
1t is uniform in color, soft, and easily sawed. A
generation ago. before the renaissance in American
architecture, the brownstone 'front.' of this ma