248 
enclosed under great pressure at a high temperature, (2) of 
gaseous vapour under enormous compression. Sir Isambard 
Brunel, and later, M. Thilorier, of Paris, succeeded in obtain- 
ing liquid carbon dioxide in great abundance. Thilorier’s 
apparatus consisted of a pair of extremely strong metallic 
vessels, one of which was used as a retort, the other as a 
receiver, made of thick cast-iron or gun-metal, or what is better, 
of the best and heaviest boiler plate, and furnished with stop- 
cocks of a peculiar kind, the workmanship of which was 
excellent, as the vessels have to bear enormous pressure. When 
the receiving vessel containing the charge has its stop-cock 
opened, a stream of the liquid is forcibly driven through a tube 
by the elasticity of the gas contained in the upper part of the 
vessel, when the experimenter incurs great personal danger in 
using this apparatus, unless the utmost care be taken in its 
management. A dreadful accident occurred in Paris from the 
bursting of one of the iron vessels, by which one of the 
chemists lost his life. 
Again, the liquid contents of these cavities in the quartz 
of granites are completely vaporised under great pressures. 
Alcohol or ether enclosed in a tube of strong glass or iron is 
completely converted into vapour, only when the space not 
occupied by the liquid is somewhat greater than the volume of 
the liquid itself. Alcohol when thus heated acquires increased 
mobility, expands to twice its original volume, and is then 
suddenly converted into vapour. This change takes place at 
207°C (404-6° F.) when the alcohol occupies just half the volume 
of the tube; if the tube is more than half-filled with alcohol it 
bursts when heated. A glass tube one-third filled with water 
- becomes opaque when heated, and explodes violently after a few 
seconds. What enormous forces then are stored up in these 
minute cells of the rock, ready to burst into action at an 
augmented temperature, and do the work of destruction and 
disintegration. 
The subject of the temperature and compression indicated 
by the lacune and their contents, liquid, gaseous, and solid, 
having been briefly given as it were in outline, some remarks 
