Page:Experimental researches in chemistry and.djvu/61

46 much nearer to the calculated result than the former) but there had still been action on the tube, and a minute portion of the substance had passed undecomposed, and condensed at the opposite end of the tube in crystals.

Experiments made by passing the perchloride over hot lime or barytes, promise to be more accurate and easy of performance. In the mean time, the above analytical results will, perhaps, be considered as strong corroboration of the opinion of the nature of the compound, deduced from the synthetical experiements; and the composition of the per chloride of carbon will be—

Protochloride of Carbon.—Having said so much on the nature of the per chloride of carbon, I shall have less occasion to dwell on the proofs that the compound I am about to describe, is also a binary combination of carbon and chlorine.

When the vapour of the per chloride of carbon is heated to dull redness, chlorine is liberated, and a new compound of that element and. carbon is produced. This is readily shown by heating the bottom of a small glass tube, containing some of the per chloride in a spirit-lamp. The substance at first sublimes; but as the vapour becomes heated below, it is gradually converted into protochloride, and chlorine is evolved.

It is not without considerable precaution that the protochloride of carbon can be obtained pure; for though passed through a great length of heated tube, part of the per chloride frequently escapes decomposition. The process I have adopted is the following:—Some of the per chloride is introduced into the closed end of a tube, and the space above it, for 10 or 12 inches, filled with small fragments of rock-crystal; the part of the tube beyond this is then bent up and down two or three times, so that the angles may form receivers for the new compound; then heating the tube and crystal to bright redness, and dipping the angles in water, the per chloride is slowly sublimed by a spirit-lamp, and, on passing into the hot part of the tube, is decomposed; a fluid passes over, which is condensed in the angles of the tube, and chlorine is evolved; part of the gas escapes, but the greater portion is retained in solution by