RTE VEROPEP RITES OF BULEDING STONES, ETC. 357 
fine grained varieties are often traversed by sharply defined 
cracks. In contrast with the limestone and granite, sandstone 
has all outward appearance of being very little injured by extreme 
heat. However, it is often so soft after being subjected to 
extreme heat that one can crumble it between the fingers. The 
extent to which a coarse grained sandstone has been injured by 
extreme heat cannot be determined until the strength of the 
stone has been actually tested. All the stone that has been 
heated to a high temperature emits the characteristic ring, and 
scratch of brick. The cause for this may be found in the loss 
of the water of composition by the minerals of the rock. 
Experiments seem to indicate that there are few, if any, stones, 
whether they be granite, limestone, or sandstone, that will effect- 
ually withstand a temperature of 1500° F. A rock with a uniform 
texture and a simple mineralogical composition apparently 
suffers the least injury when subjected to high temperatures. 
It would be interesting to know the loss of strength occasioned 
by each increase in temperature of 100 or 200° for the different 
kinds of building stones. This can only be determined by a 
careful series of experiments, and it is hoped that in the future 
some one will undertake this task. 
The effect of sulphurous acid gas—Limestone, dolomite, and 
marble are the only kinds of stone which are to any extent 
injured by sulphurous acid gas. To determine the effect of this 
gas upon dolomite or limestone, two-inch cubes are dried at a 
temperature of 110° C. and carefully weighed. They are then 
placed in a wide mouthed bottle, in the bottom of which is placed 
a beaker of water to keep the air moist. The bottle is sealed 
and each day sufficient sulphur dioxide is transferred into the 
bottle to keep the atmosphere saturated. The samples should 
be allowed to remain forty-four days in this atmosphere saturated 
with sulphur dioxide. After being removed from the bottle the 
samples should be washed and thoroughly dried at a temperature 
of 110°C. They should finally be weighed and the loss in 
weight determined. The percentage of loss in weight is taken 
as the result. The loss in this case is due mainly to the 
