42 On two new Compounds [1820. 



ters. The different portions of air that were thrown out being 

 examined, the first proved to be common air, and the last car- 

 bonic oxide. This had resulted, probably, from the action of 

 the chlorine on the lead of the glass tube. An evident action 

 had taken place, and the oxygen evolved, meeting with the 

 liberated carbon, would produce the carbonic oxide. This 

 experiment has been repeated several times with, the same 

 results. 



When the perchloride of carbon is heated with metallic 

 oxides, different results are produced according to the propor- 

 tions of oxygen in the oxides. The peroxides, as of mercury, 

 copper, lead and tin, produce chlorides of those metals, and 

 carbonic acid ; and the protoxides, as those of zinc, lead, &c., 

 produce also chlorides, but the gaseous products are mixtures 

 of carbonic acid and carbonic oxide. I have frequently per- 

 ceived the smell of phosgene gas, on passing the chloride over 

 oxide of zinc ; and as the substance easily liberates chlorine at 

 high temperatures, it will be readily seen how a small portion 

 of that gas may be formed. It also happens, sometimes, that 

 the protoxides become blackened from the deposition of char- 

 coal. 



When the vapour of the chloride is passed over lime, baryta 

 or strontia, heated red-hot, a very vivid combustion is produced. 

 The oxygen and the chlorine change places, and both the me- 

 tals and the carbon are burnt. Chlorides are produced, car- 

 bonic acid is formed and absorbed by the undecomposed parts 

 of the earths, and carbon is deposited. In these experiments 

 no carbonic oxide is produced. When passed over magnesia, 

 there is no action on the earth, but the perchloride of carbon is 

 converted by the heat into protochloride. 



In these experiments with the oxides no trace of water could 

 be perceived. 



Having thus far described the properties of the substance, I 

 shall now give the reasons which induce me to consider it a 

 true chloride of carbon, and shall endeavour to assign its com- 

 position. My first object was to ascertain whether hydrogen 

 existed in it or not. When phosphorus is heated in it, a small 

 quantity of muriatic acid is generally formed ; but doubt arises 

 as to the cause of its production, from the circumstance that 

 the phosphorus, as already mentioned, may be the source of 



