344 On two new Compounds 
Most of the metals decompose it at high temperatures. Potas- 
sium burns brilliantly in the vapour, depositing charcoal, and 
forming chloride of potassium. Iron, zinc, tin, copper, and 
mercury, act on it at a red heat, forming chlorides of those me- 
tals, and depositing charcoal; and when the experiments are 
made with pure substances, and very carefully, no other results 
are obtained. Some of the substance was passed over iron turn- 
ings heated in a glass tube. At the commencement of the sub- 
limation of the chloride through the hot iron, the common air 
of the vessels was expelled, and received in different tubes; but 
before one-third of the substance had been passed, all liberation 
of gas ceased, and the remainder was decomposed by the iron, 
without the production of any gaseous matters. The different 
portions of air that were thrown out being examined, the first 
proved to be common air, and the last carbonic 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 carboni¢ 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 proportions 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 car- 
bonic acid and carbonic oxide. I have frequently perceived the 
smell of phosgene gas on passing the chloride over oxide of zinc; 
and as the substance easily liberates chlorine at high tempera- 
tures, it will be readily seen how a small portion of that gas may 
be formed. It also happens, sometimes, that the protoxides be- 
come blackened from the deposition of charcoal. 
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, carbonic 
acid is formed and absorbed by the undecomposed parts of the 
earths, and carbon is deposited. In these experiments no car- 
bonic oxide is produced. When passed over magnesia, there is 
no action on the earth, but the perchloride of carbon is con- 
verted 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 composition. 
My 
