118 Mr. Faraday on two new Compounds [Aug. 



riments, is not too great to have arisen from errors in working 

 on such small quantities of the substance. 



A mixture of equal volumes of oxygen and hydrogen was 

 made, and two volumes of it detonated with the vapour of the 

 protochloride in excess over mercury by the electric spark. The 

 expansion was very nearly to four volumes ; of these, two were 

 muriatic acid, and the rest pure carbonic oxide : and calomel 

 had been formed, its presence being; ascertained by potash. 

 Hence it appears, that one volume of hydrogen and half a volume 

 of oxygen had decomposed one proportion of the protochloride, 

 forming the two volumes of muriatic acid gas and one volume of 

 carbonic oxide ; and that at the intense temperature produced 

 within the tube by the inflammation, the rest of the oxygen and 

 the mercury had decomposed a further portion of the substance, 

 giving rise to the second volume of the carbonic oxide, and to 

 the calomel. 



A mixture of two volumes of hydrogen and one volume of 

 oxygen was made, and three volumes of it detonated with the 

 vapour, as before. After cooling, the expansion was to six 

 volumes, four of which were muriatic acid, and two carbonic 

 oxide. There was no action on the mercury in this experiment. 

 Again, five volumes of the same mixture being detonated with 

 the vapour of the substance, expanded to 9 - 75 volumes, of which 

 6'25 were absorbed by water and were muriatic acid, and 3 - 5 

 were carbonic oxide mixed with a very small portion of air intro- 

 duced along with the fluid chloride. These experiments, I 

 think, establish the composition of the protochloride of carbon, 

 and prove that it contains one proportion of each of its ele- 

 ments. 



From a consideration of the proportions of these two chlorides 

 of carbon, it seems extremely probable that another may exist, 

 composed of two proportions of chlorine combined with one of 

 carbon. 1 have searched assiduously for such a compound, but 

 am undecided respecting its production. When the fluid proto- 

 chloride was exposed with chlorine to solar light, crystals were 

 formed, as before described. The greater number of these were 

 certainly the perchloride first mentioned in this paper ; but when 

 the retort was examined by a microscope, some rhomboidal 

 crystals were observed here and there among those of the usual 

 dendritic and square forms. These may, perhaps, be the real 

 perchloride ; but I had not time, before the season of bright 

 sunshine passed away, to examine minutely what happens in 

 these circumstances; and must defer this, with many other 

 points, till the next year brings more favourable weather. 



Compound of Iodine, Carbon, and Hydrogen. 



The analogy which exists between chlorine and iodine natu- 

 rally suggested the possible existence of an iodide of carbon, 



