1820.] of Chlorine and Carbon, $c. 47 



the fluid, and renders it yellow. Having proceeded thus far, 

 by the careful application of a lamp and blowpipe, the bent 

 part of the tube may be separated from that within the furnace, 

 and the end closed, so as to form a small retort; and on di- 

 stilling the fluid four or five times from one angle to the other, 

 all the chlorine may be driven off without any loss of the sub- 

 stance, and it becomes limpid and colourless. It still, however, 

 always contains some perchloride, which has escaped decom- 

 position ; and, to separate this, I have boiled the fluid until 

 the tube was nearly full of its vapour, and then closing the 

 end that still remained open, by a lamp and blowpipe, have 

 afterwards left the whole to cool. It is then easy, by collecting 

 all the fluid into one end of the tube, and introducing 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 imme- 

 diately 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 

 aether, and testing by nitrate of silver. 



The pure protochloride 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*4875, 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 ; 



