268 FLUORINE. 



tlian that of anhydrous hydrofluoric acid, and whose toxic properties 

 made it imi)ossible for me to continue the experiments, 



I succeeded, however, in efi'ectiug the electrolysis of this compound 

 upon employing the current produced by a battery of 90 Bunsen cells. 



Under these conditions the current passed continuously; pulverulent 

 arsenic was deposited at the negative pole, and at the positive electrode 

 gaseous bubbles were formed which rose in the liquid, but were almost 

 instantly absorbed. The liberated fluorine Avas at once taken up by the 

 tri fluoride of arsenic, AsFg, which was transformed into the penta- 

 fluoride, AsFs. This investigation, carried on for a long time, gave 

 me no fluorine, but it yielded me precious data concerning the elec- 

 trolysis of the liquid compounds of fluorine, and led me to the decom- 

 position of anhydrous hydrofluoric acid. 



In order to effect the electrolysis of hydrofluoric acid I had made the 

 small apparatus which is before you, and which consists of a platinum 

 U tube, carrying on each limb an exit tube placed above the level of 

 the fluid. 



. The two openings of the U tube were closed by corks previously 

 saturated with paraffin, as was done in all of my experiments upon 

 the electrolysis of arsenious fluoride. 



A platinum wire passed througli each stopper and was connected 

 with a battery of fifty Bunsen elements. 



I prepared at first pure anhydrous hydrofluoric acid, and found, as 

 shown by Faraday and by Gore, that it was a nonconductor. 



The experiment was varied in many ways. The result was always the 

 same. With the current given by ninety Bunsen cells decomposition 

 occurred only with the hydrous acid, and it stopped as soon as all the 

 water had been separated into hydrogen and oxygen. It therefore 

 seemed impossible to effect by this process the decomposition of hydro- 

 fluoric acid into its elements — ^hydrogen and fluorine. 



At this point I remembered that in the previous study of arsenious 

 fluoride I had sought to make that liquid a good conductor by adding 

 to it a little fluoride of manganese or acid fluoride of potassium. This 

 process was applied to the hydrofluoric acid, and then, after three 

 years of investigation, I reached the first important experiment upon 

 the isolation of fluorine. 



Hydrofluoric acid containing the acid fluoride of potassium decom- 

 poses under the action of the current; and in the apparatus which is 

 before your eyes one could obtain at the negative x)ole a regular disen- 

 gagement of hydrogen. What was there at the positive pole? Noth- 

 ing. A slight increase of pressure — that was all. Only, in dismounting 

 the apparatus it was found that the cork of the positive pole had been 

 burnt, carbonized, to the depth of a centimeter. The paraffined 

 stopper of the .negative pole was unaltered. Hence there had been 

 disengaged at the positive pole a substance having an action upon 

 cork quite different from that of hydrofluoric acid. 



