266 FLUORINE. 



This carbou was prepared with great care, by heating in a current of 

 hydrogen a dense wood, which gave him a sonorous rod, a good con- 

 ductor of electricity. The apparatus was put together; the experiment 

 begun. All at once a violent explosion occurred, and fragments of the 

 carbou were thrown to the remotest parts of the laboratory. Gore 

 repeated the experiment several times. The result was always the 

 same. Today we are able to give an explanation of the ijheuomeuon. 



The carbon, which was thus prepared by the distillation of a very 

 hard wood, was filled with hydrogen. You all know how easily gases 

 condense in carbon; the beautiful experiments of Melsens have estab- 

 lished this most clearly. When we electrolyze, with a negative pole of 

 such carbon, a conducting hydrofluoric acid, fluorine is set free, which, 

 as we shall see later, unites with hydrogen, producing a violent detona- 

 tion. In this experiment of Gore a little fluorine was set free, and it 

 was to the combination of that with the hydrogen occluded in the car- 

 bon that the explosion was due. 



l^ow I come to the new experiments, to which I call your attention. 



I began these researches with a preconceived opinion. If we sup- 

 pose for a moment that chlorine had not yet been isolated, although we 

 knew how to prepare the chlorides of phosphorus and other similar 

 compounds, it is clear that we should increase our chances of success 

 in attempting to isolate that element by working with the compounds 

 which it could form with the metalloids. 



It seemed to me that we could obtain chlorine rather by seeking to 

 decompose the pentachloride of phosphorus or hydrochloric acid than 

 by attempting the electrolysis of chloride of calcium or of an alkaline 

 chloride. 



Should not the same considerations hold good for fluorine 1 



Again, since fluorine, according to the earlier investigations, and 

 especially those of Davy, is a body endowed with very energetic 

 attinities, we should, in order to collect the element, work at the lowest 

 possible temperatures. 



Such are the general conceptions which led me to take up systemat- 

 ically a study of the compounds formed by fluorine with the metalloids. 



My attention was first given to the fluoride of silicon, and I was 

 struck at once by the great stability of that compound. With the 

 exception of the alkaline metals, which, at a dull red heat, decompose 

 it easily, few substances act upon silicon fluoride. It is easy to account 

 for this property if we remember that its formation is attended by a 

 very great evolution of heat. M. Berthelot showed long since that the 

 stability of compounds is greatest when the most heat is generated 

 during their formation. 



I supposed then, rightly or wrongly, before having isolated fluorine, 

 that if we ever succeeded in preparing the element, its combination 

 with crystallized silicon should be attended by incandescence. And 

 every time during my long researches that I hoped to have set fluorine 



