The news and herald. (Winnsboro, S.C.) 1877-1900, 1880-08-07
T0nbs.

Prof. Geikie has been examining the
tomb stones in the Edinburgh grave yards
with the view of determining the effect OF
time and weather on different kinds of
stone. His researches were necessarily
limited to the few varieties employed for
monumental purposes, namely, MAI bles,
lime stones, sandstone flag stones and
granite. He found the ordinary white sac
charoid Italian the most common marble.
Three different effects were produced on
this by the weather, namely, superficial
solution, internal dlsintegration, and curva-
ture with fracture. Superficial solution Is
caused by the carbonlc acid and partly by
the sulpl'uric acid Of the town rain.
When the marble is first erected, its high
ly polished surface is like that of mirror;
but after exposure for year or two to the
prevalent westerly rains Of that locality, its
surface becomes rough and granular, so
much 30 that it might be taken for sa1Sd-
stone. Tho grams are 80 loosely held to-
gether that they may easily be rubbed off
with the finger, Of course, in such case
the inscription becomes illegiblc in num-
Der of years, varying with the position of
tho stone. Many of the marble monuments
in the older churchyards have undergone
the process of internal disintegration.
They are found to be covered with dirty
crust, beneath which the stone proves to
he merely loose crumbllng sand. While
the outer crust lasts, the surface of
the marble remains with apparently little
change, the inscription being perfectly legi,
Die. But as soon as the crust is broken
the stone IN many cases crumbles to pow
der. The remarkable phase of a rock
weathering shown by curvature and frac-
turc was observed only in those slabs of
marble which had been inserted in solid
frame work OF sandstone, The weather
produced bulging out of the marble and
series of fractures. In some instances
the marble slab, securely fastened at the
ends and sides, bulged out in the middle
like a full sail. Professor Gcikie gives as
the results of his observations that slabs of
marble exposed to the weather, the climate,
and atmosphere of Edinburgh are, save ip
exceptionally sheltered situations entirely
destroyed in less than century. He
thinks white marble wholly unsuited for
outdoor use IN that region, and that its
employment for opcn-air works of art in
tended 10 be lasting should be strenuousy
resisted. Sand-stones and flag-stones,
when properly selected, he finds arc re-
markably durable. The best are those
which consist of a nearly pure, fine, sill.
cious sand, with little or no iron or lime,
and without trace of bedding structure
lie observed one tombstone" solid square
block OF free stone-that had successfully
resisted the action of the weather for two
hundred years. But there arc varieties of
sand and free stones whose structure and
constituents are sucn as to make them
poorly fitted for outdoor service. Profess
sor Geikie's studies of grani,e arc not con-
elusive, for the reason that this material
has been used 80 short u time lii cemeteries
He found, however, that iii time the polish
Will disappear, the surface roughcn and
decay set in lie expresses the opinion
that even the most DURABLE granite will
probably be far surpassed in pcrmancncc
by the best of the Scotch silicious sand