Pyro-eitrie Acid, §. 187 
The new fluid is also remarkable for its extreme volubil- 
ity, adhering very slightly to the sides of the cavities; and is 
likewise distinguished by its optical properties. It exists 
not in sufficient quantities to admit of chemical analysis. It 
is almost always accompanied by another fluid like water, 
with which it refuses to mix, and which does not percepti- 
bly expand at the above mentioned temperature. 
In a specimen of cymophane, or ehrysoberyl, Dr. Brews- 
ter has discovered a stratum of these cavities, in which he 
has reckoned in the space of ith of an inch square, thirty 
thousand cavities, each containing this new fluid ; a portion 
of the fluid like water; and a vacuity besides. All these 
vacuities disappear simultaneously at a temperature of 83°. 
If such a fluid could be obtained in quantities, it is ob- 
served, that its utility in the construction of thermometers 
and levels would be incalculable. There are many cavities 
in crystals, such as those opened by Sir Humphry Davy, 
which contain only water, and which, of course never ex- 
hibit any of the properties above described. | 
Edin. Phil. Journ, 
6. Pyro-citric Acid.—A new acid has been thus named by_ 
HM. i ssaigne who discovered it. It is produced by the 
distillation of citric acid. It is white, inodorous, and of a 
oxides it forms salts, differing in their properties from the ci- 
trates, M. Lassaigne has examined the pyro-citrates of 
potash, lime, barytes and lead. 
