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SELECTED ARTICLES. 
more dense than the snow already described, but nearly white, 
and very porous. If the tube be exposed to a paste of carbonic 
snow and ether, the liquid is solidified into a mass which is 
not porous, but which sinks in the liquid as the latter is formed 
again by the melting of the solid. 
The analogy between liquid carbonic acid and water, is 
thus completed, for we have liquid, vapor, snow, and ice, ex- 
hibited by both. 
By the previous introduction of water, ether, alcohol, 
metals, oxides, or oils, &c. into such tubes, and then filling 
them with liquid carbonic acid, the resulting phenomena may 
be easily observed. Water being heavier, rests below the 
new liquid, and does not appear to mingle with it even at the 
surface of contact, for when the latter is let off, no bubbles 
appear in the water, and it is frozen at the top into a solid 
ice. 
When alcohol or ether is introduced, the new liquid falls 
through it in streams, as water would do, but soon renders it 
milky by mixture. The removal of the pressure causes a 
a violent effervescence, and immediately the clear, colorless 
ether, or alcohol, is seen alone in the tube; no solid being 
formed. When alcohol holds shell-lac in solution, the acid 
causes its precipitation in light, whitish flocculi, which are 
immediately re-dissolved, when the acid is suffered to fly 
off. Nothing remains but the brown lac-stained liquid. 
Liquid carbonic acid did not appear to act on any of the 
metals or oxides, but the experiments on this point demand a 
further examination. Its inaction is probably owing to the 
want of the force of " presence," or of " disposing affinity." 
When the liquid has been frozen in a tube of glass, the 
tube may be melted off by the blow pipe and hermetically 
sealed. Such a tube will always retain the liquid, or gas; the 
former, if in sufficient quantity, at all temperatures; if not, 
the latter alone will be found in it at high temperatures. I 
have one such tube, which begins to show moisture at 56°, 
and exhibits a constantly elongating cylinder of liquid, as the 
