FLUORIC ACID. 507 



procured by the aid of sulphuric acid,* there would seem to be no 

 reason to doubt that it must contain water,f the decomposition of 

 which, according to the opinion of Gay-Lussac and Thenard, affords 

 the hydrogen which is evolved and supplies oxygen to the potassium, 

 by which it becomes potassa and unites with fluoric acid to form an 

 acid fluate of potassa. In this experiment, therefore, there seems no 

 reason to admit that the fluoric acid is decomposed, and it would be 

 premature to say that it consists of oxygen and a combustible basis, 

 although such a constitution is certainly both very possible and very 

 probable. 



On the whole, we must, for the present, and until additional re- 

 searches shall clear up the difficulty, rank fluoric acid among the un- 

 decomposed bodies :{ although from analogy, I have placed it with 

 bodies known to be compound. 



EQUIVALENT OF FLUORIC ACID. 



Dr. Thomson,^* has concluded that the representative number of 

 fluoric acid is 10, and Berzelius has formed the same conclusion 5 

 this is upon the supposition that the fluates are compounds of fluoric 



* It would seem that the fluoric acid exists anhydrous in fluo-silicic and fluo-boric 

 gas, and in its own saline compounds, fluor spar, &c. but that it cannot be separated, 

 in its pure state, from its combinations, except by the aid of an acid that contains 

 water. 



t Especially if the sulphate of lime remaining in the distilling vessel be, as it 

 doubtless is, anhydrous ; for besides the strong affinity of the fluoric acid for water, 

 the residuum in the vessel is usually heated to a degree that expels all water from 

 the natural hydrous sulphates of lime, and 1 have found it very hard to detach. 



t Deference to the opinions of very able men, and to the practice of some of the 

 most respectable chemical authors, would have led me to place the' hypothetical 

 principle fluorine, in the text and in the tabular arrangement. But it appears plain 

 that fluorine would never have been thought of, but for the supposed analogies with 

 chlorine, which controverted topic was keenly agitated about the time of the princi- 

 pal modern researches upon fluoric acid, and the extension of these analogies, by the 

 discovery of iodine, almost at the same period, seemed to make it, in a sense, neces- 

 sary to admit the existence of a similar principle in fluoric acid. These analogies 

 may be mentioned again, after we have gone through with the history of chlorine 

 and iodine. For the present, however, it may be remarked that there is no decisive 

 experiment, proving the existence of fluorine. 



When Sir H. Davy galvanized the strongest liquid fluoric acid, an inflammable 

 gas, doubtless hydrogen, was disengaged at the negative pole, and the platinum wire" 

 was rapidly corroded at the positive ; while a chocolate colored powder collected 

 on the wire. As it does not appear to have been examined, we are in na condition 

 to decide whether it was, as imagined, a compound of fluorine with platinum, or an 

 oxide of that metal. We do not know whether the solvent powers of the fluoric 

 acid, great as they are, may not have been so exalted by the galvanic energy, that 

 this agent may have become capable, in its acid character, of attacking even plati- 

 num, while it would be even possible that the oxygen requisite to oxidize the metal 

 may have been derived from the water which would then give out the hydrogen, its 

 other element at the negative pole. 



To me it appears premature, to place fluorine, a principle purely hypothetical,, 

 along side with chlorine and iodine, whose distinct existence and peculiar energy 

 are manifested in so many remarkable forms. 



First Prin. Vol. II. 



