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SELECTED ARTICLES. 
From — 4° to 32° its expansion is almost exactly equal to that 
of the gases. 
M. Thillorier found also that the expansive force is altered 
by heat so as to amount at 86° to 73 atmospheres, and at — 4° 
to 26 atmospheres. The density of the gas when resting over 
the liquid at 86°, is stated at 130 times the density of that 
which is compressed by the force of one atmosphere. Its 
pressure is therefore at S6° not much more than one-half of 
that which its density would indicate. 
When liquid, the carbonic acid is, on the same authority, 
immiscible with water and the fat oils, but is readily united 
with ether, alcohol, naptha, oil of turpentine and carburet of 
sulphur. Although potassium decomposes it, lead, iron, cop- 
per, and the other easily oxidized metals, do not act on it. 
Among the most remarkable of the phenomena observed by 
Thillorier was the intense cold produced by the sudden libe- 
ration of the liquid and its conversion into gas. A jet of it 
depressed the thermometer to — 130°F., and when sulphuric 
ether had been previously mixed with the liquefied gas, the 
refrigerating effects were more marked both on mercury and 
the sensations.* 
At the immediately subsequent sitting of the Academy of 
Sciences, Thillorier announced the important fact that he had 
solidified carbonic acid. This he effected by suffering the 
liquid to escape into a bottle, or box, where by the sudden 
gasefaction of a part, the remainder was frozen by the ex- 
treme cold thus produced. The solid is white, light, evapo- 
* The thermometric temperature observed in the jet by Thillorier, ap- 
pears to be erroneously stated ; for, as the solid is, at its formation, not 
below — 90°, and as the act of solidification of any vapor or liquid keeps 
the temperature, for the time, at the highest point compatible with the ex- 
istence of the particular solid under observation, it follows that the jet of 
carbonic acid cannot fall below its freezing point. Immediately after its 
production, the carbonic snow begins to grow colder, and may be made 
to reach — 109° in the air, — 136° under an exhausted receiver. When 
moistened with ether, it can be depressed to —146°. Professor, Hare's 
ether acts much more effectually than sulphuric ether. 
