The Ohio Democrat. (Logan, O. [Ohio]) 1886-1906, 1890-04-26
TO PREVENT DECAY.
A Matter of Utmost Importance to tho
Consumers of Stone.

|
| A Matter of Utmost Importance to tho
| Consumers of Stone.
Prof. Tptmaier, OF Zurich, one of the
greatest living authorities on such sub
| iects. made recently an investigation
into the causes of the decay of stone in
buildings, and the best means of pre-
venting it. Many of our readers will
remember Viollet-le-Duc's striking OBJ
servations in regard to tho same matter,
deduced from an immense experience,
and Prof. Tetmaier's conclusions agree
entirely with his. According to both,
the freezing of water in the pores of
stone is the principal cause Of its disin-
tegration. Even the chemical effect of
the air in large cities, due, it is sup
| posed, to the sulphurous acid contained
in it, probably acts through the rain
water, by which the acid is washed out
of che air. and carried to the stone, so
that any thing that will prevent the ac-
emulation of water in the pores is
likely to diminish chemical action, as
well as risk from frost. Contrary to the
common idea, the most porous stones
are, if properly used, not necessarily
most subject to disintegration. If the
water falling on the stone has chance
to escape freely, frost will not iniure it,
but If the movement of the water in the
pores is checked, so that it accumu-
lates anywhere, the freezing of this
accumulation will gradually destroy
even strong stone. Proofs of this may
be found in nearly all buildings faced
with sand or limestone. If the base, or
water-table, or even belt at any
height is of harder stone. the freestone
just above it will be found to disinte-
crate after few years, owing to the
checking of the downward movement of
the water in the pores So, on the under
side of projecting moulding, or bal
! cony. where the water accumulates by
gravitation, but is prevented by capil-
larry attraction from dropping Off flakes
of stone will soon be observed to sepa-
rate and fall; and soft stone near the
ground where moisture drawn up from
the earth by capillary attraction, joined
with the double effect of the rain, and
the spattering Of rain-water from the
ground, keep it particularly moist, soon
perishes. The decay Of stone shows it
self in two ways With a stratified stone,
y
working in the natural seams, but with
massive, homogeneous stone, the effect
of freezing is to discover the PARTICLES
of sand, or the crystals of carbonate of
lime, so that, although the stone may
for long time hold together nearly in
its original shape, the rubbing of the
hand will dislodge a shower of sand, and
the profiles and arrifes insensibly lose
their sharpness.
The cure for this is, in the first place,
to treat the stone with skill. A soft
stone, if laid above hard course, should
be protected from the rain, so that no
water will descend through its pores, to
be checked by the hard layer; the lower
courses of buildings should be of as hard
and impervious material as possible,
and vertical joints should be packed
hard with cement and jointed, as imper-
feet joints collect much water, which
soaks afterwards into the stones on each
side; and all projecting courses should
have drip, which will collect the water
in the stone and enable it to drop off.
In cases where nothing better can be
done. tho old process of Faure & Kcssler,
now of Clermont- Ferrand, in France, by
which the stone is impregnated with
fluosilicates of various substances, ac-
cording to the character of the stone to be
treated, is the only one which has proved
itself successful. Something might be
done, perhaps, with lime-water, and it
is curious that where q base-moulding
has begun to decay, the portions under
the vertical joints of the course of stone
Immediately above, from which small
quantities of dissolved lime have proba-
bly, washed down on the moulding be-
meath, are preserved, while the inter-
mediate portions are disintegrated; but
this application has not been studied to
a successful result. In the case of stone
not built into wall, it is often found
that while damp with quayry-sap, or
soaked with rain-water, sudden frost
will split the blocks into Fragments and
this must be provided against by keep
ing the stone dry; but Prof, Tetmaier
and his assistants report that they have
never known a stone to burst with frost
after it was built into wall.-American
Architect.