114 Mr. Faraday on two new Compounds [Aug. 



cubic inches, barometer 29*85 ; thermometer 54° Fahr. Of 

 these nearly 3 - 8 cubic inches were carbonic acid, and rather 

 more than -1 of a cubic inch was cavbonic oxide. These are 

 nearly equal to -5004 of a grain of carbon. Hence, 100 of the 

 chloride would give 10 of carbon nearly, but by calculation 100 

 should give 10* 19. The difference is so small as to come within 

 the limits of errors in experiment. 



Five grains were passed over peroxide of copper in a tube 

 made of green phial glass, and the chlorine estimated in the 

 same manner as before. 17*7 grains of chloride of silver were 

 obtained equal to 4*36 grs. of -chlorine. This result approaches 

 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 experiments ; 

 and the composition of the perchloride of carbon will be 



3 proportions of chlorine = 100*5 



2 ditto carbon = 11-4 



111-9 



ProtocJi/oride of Carbon. 



Having said so much on the nature of the perchloride of car- 

 bon, 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. 



V/hen 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 heat- 

 ing the bottom of a small glass tube, containing some of the 

 perchloride in a spirit lamp. The substance at first sublimes, 

 but as the vapour becomes heated below, it is gradually con- 

 verted 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 perchloride frequently 

 escapes decomposition. The process I have adopted is the fol- 

 lowing : 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 compound ; then 

 heating the tube and crystal to bright redness, and dipping the 

 angles in water, the perchloride is slowly sublimed by a spirit 



