66 
Mr. Faraday on two new compounds 
the end that still remained open, by a lamp and blow-pipe, 
have afterwards left the whole to cool. It is then easy by 
collecting all the fluid into one end of the tube, and introduc- 
ing that end through a cork into a receiver, under which a 
very small flame is burning, to distil the whole of the fluid at 
a temperature very little above that of the atmosphere. The 
solid chloride being less volatile does not rise so soon, and 
the pure proto-chloride collects at the external end of the tube. 
To ascertain its purity, a drop may be placed on a glass plate ; 
it will immediately evaporate, and if it contains perchloride, 
that substance will be left behind ; otherwise, no trace will 
remain on the glass. The presence or absence of free chlorine 
may be ascertained by dissolving a little of the fluid in alcohol 
or ether, and testing by nitrate of silver. 
The pure proto-chloride of carbon is a highly limpid fluid, 
and perfectly colourless. Its specific gravity is 1.5526. It is a 
non-conductor of electricity. I am indebted to Dr. Wollas- 
ton for the determination of the refractive power of this chlo- 
ride, and for the approximation to the refractive power given 
of the perchloride. In the present case it is 1.4,875, being 
very nearly that of camphor. It is not combustible except 
when held in a flame, as of a spirit lamp, and then it burns with 
a bright yellow light, much smoke, and fumes of muriatic acid. 
It does not become solid at the zero of Fahrenheit's scale. 
When its temperature is raised under the surface of water to 
between 160° and 170°, it is converted into vapour, and re- 
mains in that state until the temperature is lowered. When 
heated more highly, as by being passed over red hot rock 
crystal in a glass tube, a small portion is always decomposed ; 
nearly all the fluid may, however, be condensed again, but 
