46 On two new Compounds [1820. 



preaches much nearer to the calculated result than the former; 

 but there had still been action on the tube, and a minute por- 

 tion 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 perform- 

 ance. In the mean time, the above analytical results will, per- 

 haps, be considered as strong corroboration of the opinion of the 

 nature of the compound, deduced from the synthetical experi- 

 ments; and the composition of the perchloride of carbon will be 



Three proportions of chlorine .... =100'5 

 Two ,, carbon . . . . = 11*4 



111-9 



Protochloride of Carbon. Having said so much on the 

 nature of the perchloride of carbon, I shall have less occasion 

 to dwell on the proofs that the compound I am about to de- 

 scribe, is also a binary combination of carbon and chlorine. 



When the vapour of the perchloride 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 perchloride in a spirit-lamp. The substance at first sub- 

 limes ; 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 protochlo- 

 ride of carbon can be obtained pure; for though passed through 

 a great length of heated tube, part of the perchloride frequently 

 escapes decomposition. The process I have adopted is the 

 following : Some of the perchloride 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 com- 

 pound ; then heating the tube and crystal to bright redness, 

 and dipping the angles in water, the perchloride is slowly sub- 

 limed 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 



