Messrs. Knox on the Insulation 0/ Fluorine. 133 



the water present, and consider it probable that it was a fluoride of oxygen formed 

 by the union of the nascent oxygen and fluorine. To determine this, we heated 

 in a dry glass tube a mixture of iodic acid and fluoride of mercury, supposing 

 that when the iodine decomposed the fluoride of mercury, fluorine and oxygen 

 being set free from their combinations with oppositely electrical bodies (mercury 

 and iodine) would be in the most favourable condition for combining. On 

 applying a moderate heat a yellow gas arose, which did not act on the glass, and 

 bleached litmus paper slightly; on increasing the temperature, the yellow iodide 

 of mercury sublimed, then iodine, and finally fluoride of mercury. 



We have to remark, with regard to our present mode of manipulating, that 

 about 100 grains of the fluoride of mercury la a sufficient quantity ; but that its 

 absolute dryness must be ascertained, which may be known by its subliming plen- 

 tifully out of the mouth of the vessel. It requires about two hours to effect this, 

 and to raise the temperature of the fluor vessel sufficiently high previous to passing 

 in the chlorine. When filled with the chlorine, which must be also well dried, 

 we apply the heat of Rose's spirit lamp, with circular wick, for about twenty 

 minutes, which we find to be always sufficient for the decomposition of the 

 fluoride. When we have examined the contents of the vessel, after a quarter of 

 an hour, we have found chlorine in it, but never when it has been heated the 

 above length of time. If, instead of drying the material perfectly. It happened 

 that a trace of moisture was allowed to remain, then, Instead of the usual result, 

 we obtained copious fumes of hydro-fluoric acid. 



In conclusion, we beg to state, that we are far from wishing it to be sup- 

 posed that we consider the doubts on the nature of fluorine set at rest by the 

 foregoing researches. But we think ourselves justified, from the experiments 

 we have detailed, to conclude, that some advances have been made, and that a 

 mode of operating on that element has been pointed out, which may be suc- 

 cessfully employed hereafter, and which, in other hands, may lead to more 

 complete results. 



