128 Messrs. Knox on the Insulation of Fluorine. 



vapour of hydro-fluoric acid through a platinum tube heated red hot ; and by 

 distilling it from salts containing abundance of oxygen or of chlorine. He dis- 

 tilled also the fluorides of lead and mercury with phosphorus and sulphur in glass 

 tubes, with the formation of a phosphuret and sulphuret, and action on the glass ; 

 when the glass tubes were lined with sulphur, a limpid liquid condensed in a 

 part of the tube cooled to zero. 



From these experiments he concludes, that there exists in the fluoric com- 

 pounds a peculiar element, possessed of strong attraction for metallic bodies and 

 hydrogen, which from the low refractive power of hydro-fluoric acid, he supposed 

 would have less refractive power than any substance known, possessing at the 

 same time higher acidifying and saturating powers than either oxygen or chlo- 

 rine, and which, when obtained in an insulated state, would prove to be a gas. 



We understand that Sir H. Davy got vessels of fluor-spar made for the pur- 

 pose of repeating these experiments, but since he has not published any which he 

 may have tried with them, we conclude that he either did not employ them, or 

 that they did not conduct him to any new results. 



Such was the state of the subject till the year ]836, in the spring of which 

 year we commenced the following investigation. Sir H. Davy's experiments 

 having shown that chlorine would decompose fluoride of mercury in glass vessels, 

 it became a question to determine whether the same result would take place in 

 vessels upon which the nascent fluorine could exert no action. This we tried by 

 heating dry chlorine with fluoride of mercury in two small perforated crystals of 

 fluor spar. A chloride of mercury was formed. Then, in small vessels of fluor- 

 spar containing chlorine, we heated fluorides of mercury, lead, and hydrofluate of 

 ammonia ; in the first were formed crystals of corrosive sublimate ; in the second 

 the fluoride of lead was not acted upon ; and the last vessel was filled with 

 vapour of hydro-fluoric acid. We then procured fluor-spar vessels of a larger 

 size, lapped with wire, for the purpose of equalizing the temperature, and so 

 preventing the vessels from splitting on a sudden application of heat. Instead of a 

 flat cover for the vessels we had fluor-spar receivers made, the cavities of which 

 were filled witli ground-stoppers of fluor. On moving the receivers over the 

 mouth of the vessel the stoppers fall in, and their places in the receivers are 

 occupied by whatever the contents of the vessel may be. On the top of these 

 vessels were three or four small depressions, in which were placed any substances 

 that we wished to submit to the action of the gas, and over which the re- 



