22 ROYAL SOCIETY OF CANADA 
ordinary temperatures; finally a permanent condition was reached, 
but not until the bar [which seems to have been 3 ft. in length] was 0.2 
to 0.8 mm. longer at ordinary temperatures than originally. The 
length at 100° C. was practically constant from the first.” 
In an article on “The Physical, Chemical and Economic Properties 
of Building Stones” by Geroge P. Merrill, published in 1898', there is a 
further discussion of this permanent expansion which takes place when 
rocks are heated. After referring to the economic and geological im- 
portance of the fact that the tenacity of stone is weakened through ex- 
pansion, he goes on to say: 
“Within recent years, some good work in this line has been done 
under the direction of the Ordnance Department of the U. 8. Army. 
The method of testing has consisted in placing carefully measured bars 
of stone in baths of cold water (32° F.), hot water (212° F.), and back to 
cold water once more. It was noted that in none of the samples tested 
did the stone quite regain its first dimensions on cooling, but showed a 
slight ‘permanent swelling’. Since this can only mean that the particles 
composing the stone have separated though ever so slightly, it is an im- 
portant matter as it necessitates a weakening, which is shown by actual 
pressure tests.” The mean of the results obtained of the permanent 
swelling occurring in stone bars of a gauged length of 20 inches is, for 
granites, .0040 inch; for marbles, .0090 inch; for limestone, .0070 inch; 
and for sandstones, .0047 inch. “The average result showed that the 
stones from the water baths lost in strength on an average 34.9 per cent, 
the granites, after passing through the hot and cold water tests, posses- 
sing but 83.7 per cent. of their original strength; the marbles, 46.2 per 
cent; the limestones, 58.8 per cent; and the standstones, 66.9 per 
cent.” 
“The amount of expansion of rocks,” according to Dana in his 
Manual of Geology, “is mostly between 1 and 10 millionths for 1° F. and 
1 millionth corresponds to 1.2 thousandths of an inch for 100 feet.” 
After quoting results of Totten and Adie, he adds, “ Pfaff found for the 
expansion between the ordinary temperature and red heat (about 
1750° F.) of granite [one inch in length] from the Fichtelgebirge, 0.0168; 
for porphry from the Tyrol, 0.0127; and for basalt of Auvergne, 
00120.” 
A short investigation was conducted at McGill in the Autumn of 
1909, by Dr. H. L. Bronson and Mr. G. St. G. Sproule under the direction 
of Dr. H. T. Barnes and Dr. A. Stansfield, for the purpose of determining 
the relative thermal coefficients of expansion of certain rocks and of a 
certain nickel-steel alloy, which was required in connection with some 

‘ Maryland Geological Survey, Vol. 2, pp. 47-123. 
