ME. G. GOEE ON THE PEOPEETIES OF LIQUID CAEBONIC ACID. 
87 
solved and unaltered in appearance. Pitch softened and partly dissolved. Napthalin 
dissolved in small quantity. Gutta percha ; the liquid acid dissolved out the dark-brown 
colouring matter, and left the gutta percha undissolved, and much more white. India- 
rubber remained black externally, but became perfectly white through the whole of its 
thickness ; on removing it from the acid it suddenly swelled to a large size, and then 
gradually shi-ank in a few hours to its original dimensions, and afterwards (in a few days) 
slowdy regained its original colour. Common yellow resin dissolved slightly. Gum-copal 
remained undissolved. Camphor dissolved rapidly and formed a clear colourless liquid. 
(Sph’it of turpentine dissolves more than its own volume of gaseous carbonic acid.) Sper- 
maceti, indigo, pyroxylin, and solid extract of litmus remained undissolved and unaltered. 
Gamboge dissolved in minute quantity and formed a slightly-yellow liquid. 
These experiments show that liquid carbonic acid is a chemically inert body, and is 
also a very feeble solvent of substances in general, and is not deoxidized by any of the 
ordinary deoxidizing agents except the alkali- metals. 
The way to discharge the tubes of their contents is to support them over a gutta- 
percha vessel within the safety-cage, or behind a double screen of glass and wire-gauze, 
and, protected by gloves, cut off the binding-wires with a pair of nippers ; then, if the 
stoppers are not blown out, pour boiling water upon them. Sometimes the explosion 
occurs immediately upon cutting the wires, but in most cases it requires the application 
of the hot water ; this is a most convincing proof of the tightness of the stoppers, as the 
pressure of liquid carbonic acid (according to different authorities) varies from 500 to 
1100 pounds per square inch, according to the temperature of the atmosphere. The 
tubes nearly always break by the violence of the recoil. In many instances a safer plan 
was adopted ; the wires were not cut, but a current of steam was directed upon the 
stoppers until they were expelled ; the discharge was then less sudden, and the tubes 
were less frequently broken. It would probably be a still further improvement if the 
lower end of the tube was closed by a stopper in a similar manner to the upper end ; the 
contents of the tube might then be discharged at that end, and the substances operated 
upon would then be exposed to less risk of being lost, and of being brought into contact 
with the acid and saline matters by the discharge. 
In an endeavour in one experiment to liberate the enclosed acid gradually, a small 
hole was made lengthwise through the stopper before inserting it ; a piece of glass 
tubing, half an inch long and possessing a very fine bore, barely visible to the unassisted 
eye, was fixed in the hole at the small end of the stopper, and a small metal plug fixed 
in the outer end of the hole ; and after generating the liquid acid the metal plug was 
withdrawn ; nearly the whole of the liquid carbonic acid escaped through the fine apeiv 
ture of the glass in about four seconds, and left the remainder in a solid state in the 
tube. In two instances, tubes with cracks in them half an inch in length, withstood the 
full pressure of the acid during several days. 
