Evening star. [volume] (Washington, D.C.) 1854-1972, 1869-09-24
NEW BUILDING MATERIALS.

materials used has caused q pretty active az .
ercise OF inventive genius to discover some
mode OF making artificial stone possessing the
properties OF durable stone Many or most Of
these inventions have proved worthless on
being tested The artificial stone used at the
Howard University, made from sand on the
ground, seems, however, likely to solve the
problem afhrmauyely, snd it Is, moreover of
an agreeable color, making it Q great improve.
ment estheticaiiy over the dreary red brick, or
the glaring white marble Of stereotype use
Some Of the stone blocks, hurriedly male and
used in a green condition, proved defective in
the hospital building connected with the Uni
versity, but the material used in the m.in
building seems to stand well, and to harden
by exposure.
We see that an artificial stone made by
French inventor. NJ. Coignet, has come into
extensive use In France. Though the discov.
cry was looked upon with distrust at first
Its strength has been established In q way to
satisfy the scruples of the French Govern.
ment engineers, anc several important public
works have been constructed of the new
stone, which has received the name OF beton-
CJignet. Ii Is asserted tina, IL has a strength
superior to any stratifed rock, and equal to
any OF the harder rocks, except the very best
quality Of granite.
The difficulty in the way of manufacturing
artificial stone from sand nas been from the
fact that sand cannot be compressed by ordi-
nary means, and in q confined mass OF sand
pressure cannot be transmitted.
For example, if an ordinary gas or water
Pipe be filled with sand, and a piston applied
at one end, no amount of pressure can drive
the sand through ii, though the pipe NAV
burst from the lateral pressure. Here, then,
49,
proportions had been tried, but they had been
poured into moulds, or frames, in masses;
pressure had only affected them, as it were. on
the surface, and the whole interior had been
left with honeycomb OF interstces between
the grains Of sand. imperfectly filled with
hydraie of lime, which, as the water eyaporat
ed, became larger, and finally so large a. to
leave mere heap Of dry sand and lime In
fact- mortar ready to erumble. from its own
weight, under the influence of the atmosphere.
The problem How became this Given the chem.
ical constituents OF any particular stone, to
com bine them so that all air should be expeIlsd
from between the particles, and they should
form homogeneous mass. The easIsst
cheapest, and quickest way to accomplish the
desired end was found to be, by Introducing
smaller quantities OF the mixture into the
mould, and then to expel the air by pounding,
case the confined AIR would act as an elastic.
resisting cushion, which would neutraIizs the
effect Of the operation
The process OF manufacture is simply To mix
the Constituent parts in a cylinder with opIy
enough water 70 make them cohere Whez
thoroughly mixed, the material is placed in
small quantities In the moulds and pounded
With light hammers, additional quantities being
introduced until the mould is niled.
At once the moulds car be removed and the
artificial stone will be found hard and solid
and IN a few days ready for transportation even
by land-carriage, though IL continues TO in
crease In weight and density, tor from nine to
twelve months, while the moisture is gradually
evaPoranns and its place being taken By car
bonic acid.
This material has not only been used largely
on land instead OF stone, but also for submarine
structures requiring great solidity. The Jet.
ties al the entrance Of the Suez Canal are CON.
sirueted OF what appears TO be immense blocks
Of stone but this material really the artificial
stone under notice, made from sand dredged
from the bottom Of the canal mixed with
hydraulic lime, and then packed into wooden
cases or moulds and allowed TO dry.
II has been suggested that the problem of the
SPHINX, the Pyramids, and those Egyptian
whose hardness bluBts the edge Of
our sharpest tools, while their weight defies
the lifting capacity Of our most powerful ma.
chInery. il now solved, and that 10 dis eevering
the method CT making an artificial stone, M.
Coignet has but recovered the rudi nentary
principles Of an art which, IN Its most perfect
form. was familiar to the Egyptians. The
question Is, Of course, bit a mere speculation;
yet should the supposition prove TO be correct,
how easy TO account for these wonderful prodi-
gles wilderness Of sand around them and
no known deposits of such stone as forms
them-vhat more natural supposition than
that he material is but high grade of the very
artificial stone which IL now being used al the
Isthmus OF SueZl