247 
the limits within which these rocks contract on passing from a 
fluid to a solid state. 
“Granite, granulites, and quartziferous porphyrites, &c., 9 to 10 per cent.” 
Were this subject carried further, it would however valu- 
able as an aid to speculation on the cooling of igneous rocks in 
its bearing upon the shrinkage of the crust of the earth, not 
materially serve the present purpose, and the same remark will 
apply to the opposite direction, namely, of the expansion of the 
same kind of fundamental rocks. 
In the Bridgewater Treatise by Mr Charles Babbage (1837) 
at page 200, there is an account given of some expansions 
determined by the experiments of Mr Adie, and published in 
the Transactions of the Royal Society of Edinburgh, Volume 
XIII. These expansions are for Scotch granites. 
Aberdeen Grey granite us 00000438 
Peterhead Red granite oa “00000498 (Adie) 
One instance only may be cited as regards the expansion 
of Quartz from heat, by Sir Wm. Thompson, F.R.S., taken by 
him from Clarke’s Constants of Nature. 
Taste I. (Linear Expansion of Solids.) 
Quartz. Mean Expansion. Range. Authority 
810, along axis + ‘00000781 40 Fizeau 
SiO, normal to axis + ‘000001419 40 " 
TaBLE II. (Cubical Expansion of Solids.) 
Quariz. Mean Expansion. 
SiO, 000040 
These co-efficients of expansions are too inconsiderable to 
apply to our subject, and attention will be simply invited to 
consider the pent up forces enclosed in the rock cavities of 
quartz, and imprisoned at the temperature just now given, viz: 
360°, and the pressure corresponding to that temperature. 
Next in connection, reference may be made to the liquified 
carbon dioxide so frequently occurring as enclosures in the 
cavities, and on returning to the recorded descriptions by 
chemists, of the experiments on the liquefaction of this element, 
we are impressed with the power of resistance displayed, and 
the consequent danger incurred in both respects, (1) of water 
