61 
by Thilorier, was from 0° to 30°, and, as shewn above, the expansion in- 
creases so much as the temperature rises that the average rate for 1° is 
very indefinite. The only reliable method is therefore to compare the ex- 
pansion between equal degrees of temperature. According to Thilorier * 
liquid carbonic acid, when heated from 0° to 30°, expands from 100 to 145. 
One of the experiments described above showed that the liquid in sapphire 
expands from 100 from 152 ; and the other from 100 to 150, which is the 
most reliable. This agrees so closely with the expansion of liquid carbonic 
acid, that the difference might easily be due to a slight error, in the ther- 
mometers. The expansion of ordinary liquids is not to be compared with it 
nor is that of liquid sulphurous acid. Dr. Frankland has kindly ascer- 
tained this fact ? with special reference to the case in question, and found 
that from 0° to 32° C. the expansion was only from 100 to 104'36 instead 
of to 217. 
According to Andreefft the expansion of liquid nitrous oxide is not 
much inferior to that of liquid carbonic acid, being, from 15° to 20°, '00872 
for each degree, which differs decidedly from that of the liquid in sapphires. 
The occurrence of nitrous oxide in minerals is also so very much more im- 
probable, that, on the whole, it seems as if we should be justified in con- 
cluding provisionally that it is liquid carbonic acid, which like water, should 
therefore be classed amongst natural liquid mineral substances. 
Brewster has shownj that when cavities in topaz contain less than one- 
third of their volume of the expansible liquid, it does not expand when 
heated, but [passes entirely into the state of a compressed vapour. Un- 
fortunately he does not state the temperature at which this occurs, nor 
does he seem to have tried to ascertain the exact limit of the volume, which 
must, however, lie between one-half and one-third. Cagniard-Latour§ 
found that when ether and other liquids sealed up in small strong tubes, 
with a certain space left empty, were heated, they expanded very much, 
and suddenly passed into the state of vapour. The temperature, pressure, 
and volume at which this change took place varied very considerably. 
Ether expanded to nearly double its volume, and passed into vapour at 
about 200P O. , with an elastic force of 37 or 38 atmospheres. Alochol 
expanded to about three times its volume, and passed into vapour at about 
* Gmelin's Handbook of Chemistry, Cavendish Society's Translation, 
vol. i. p. 225. 
t Liebig's Ann. vol. ex. p. 1. 
t Trans. Roy. Soc. Edin. vol. x. p. 25. 
§ Pogg, Ann. vol. cv. p. 460. 
