402 Miscellanies. 
Communicated by Prof. J. Griscom. 
4. Properties of Liquid Carbonic Acid; by M. Tuiorter.— 
Within the walls of Faraday’s tube is a new chemical world, the 
phenomena of which are totally unexpected: to mention at this 
time only liquefied carbonic acid, whose properties, in common with 
permanent liquids—dilatation, vaporization, &c.—are exalted, am- 
plified, and developed upon a scale truly gigantic. 
Dilatation.—This liquefied gas presents the strange and paradox- 
ical fact of a liquid more dilated than the gases themselves; from 
0° to +30° Cent. its volume is increased from 20.to 29; that is to 
say, at +30 Cent. the increase of volume is nearly equal to the 
half of its volume at0°; ina word, its dilatation is four times 
greater than that of air, which from 0° to +30° Cent. would be 
dilated only %,°,, whilst the dilatation of liquid carbonic acid, redu- 
ced to the same scale, is a04 
Vaporization.—If we raise the temperature of a tube containing 
a thin stratum of liquid carbonic acid, it enters into ebullition, and 
the empty space above the liquid is saturated with a quantity of 
vapor which increases with the temperature. At +30° Cent. the 
quantity of liquid at O° necessary to saturate the empty space, is 
represented by a stratum of liquid equal to a third of the space in 
which the evaporation was effected. At 0° the stratum of liquid of 
saturation is only ;', of the space saturated. 
Pressure.—F rom 0° Cent. to +380° the pressure of the vapor 
furnished by the liquefied gas rises from 36 atmospheres to 73 ; which 
gives an increase of one atmosphere for each centigrade degree. It 
is necessary to observe, that the weight or density of the vapor in- 
creases in a much greater proportion than the pressure, and that the 
law of Mariotte does not apply within the limits of liquefaction ; if 
we took the density of the vapor for the basis of pressure, the pres- 
sure at +30 Cent. would be equal to 130 atmospheres, while the 
- manometer indicates really but 73. 
Thermoscopic effects.—If we subject to the action of heat a tube 
of glass containing a stratum of liquid and pnocliety gas, two con- 
trary effects will appear. 
1. The liquid will increase by dilatation. 
2. The liquid will diminish by vaporization. 
The thermoscopic effects will be very different neghedice as the 
liquid stratum is greater or less than the gaseous stratum: hence the 
