/. Nicklis on Fluorine, S95 



Art. XSX,~Iie7narhs on Fluorine: Actmi of Adds on Glass; 



hj Jerome Nickles. 



usual 



not siliceouSj is to set the flLiorine free as fluohjdric acid com- 

 monly from a vessel of lead or platinum and subject to its action 

 a plate of glass. The process has been long in use, and is of 

 value when there is much fluorine present- When the substance 

 under examination contains only a trace of fluorine, and no cor- 

 rosion of the glass is visible to the naked eye, it has been known 

 that the effects of tlie reaction could be rendered visible by 

 moistening the surface slightly with the vapor of water or with 

 the breath; the parts acted on become distinct, and remain so 

 as long as the slight film of vapor continues. This trial has till 

 now been relied ov\ with full confidence. On its indications, the 

 presence of fluorine in many rocks and mineral substances has 

 Been admitted ; and what is most to be wondered at is, that this 

 element has not been found everywhere, since the reagents used 

 in developing it themselves contain it.* 



In fact, sulphuric acid, purified by whatever known process^ 

 may still contain some fluorine, which it has received through 

 the nitrate of soda employed for oxydizing the sulphurous acid. 



Again, another cause for the corrosion of the sjlass is found 

 in the action of the acids themselves when in the state of a 

 vapor, which, in cases like those under consideration, may 

 sometimes equal that of fluohydric acid itself. The following 

 simple experiment, vrhich may be made in a quarter of an hour^ 

 proves this point. Cover a plate of glass, as usual, with wax^ 



* Since the publication of the above note in the Comptes Eendus for Mnrcl>, 

 I85Y, a reclamation of priority Las appeared, which justifies what I hare said. ^ This 

 reclamation is from Mr. Wilson, Professor of Chemistry at Edinburg, and it was 

 presented to the Royal Society of that city. He there estabhshe? that ten year^ 

 since he found fluorine not only in tl>e Wood and all the liquids of the orijanism, but 

 ako in plants, various waters and minoral5!, that is, probably, wherever he s^ougrht 

 ^or it The same thing happened to me when I bt^yan my researches, and the diffi- 

 culty was to find a substance that did not contain it. I fri\;nd it in the crucibles 

 "whicli I nsed. and the capsules in which I evaporated the waters; but then T had 

 Bot found it in the sulphuric acid us«d in my invcstigatums. This I afterwards suc- 

 ceeded in doing, (see a paper beyond,) and thi:^ put a new pliase on tl^ pn.blem, 

 and I was led even to doubt its presence m bones. Before; I could obtafn fluorine 

 from the carapax of the hvbster; but now, using sulphuric acid pure from fluorine, I 

 find none in even 200 grama of the carapax. It is phdn that if a fliKiriferous acid 

 t>e used, the presence of fluorine will l>e shown in the results. Moreover the v;ip<>r* 

 of sulphuric acid can act feebly like a f*^eble amount of fluohydric acicf and produce 

 an impression on glass appreciable after being breathed upon. As Prof Wilson 

 ^ade his experiments with sulphuric acid, and with large quantities of it. he sho"W 

 We had traces of its presence. He states that he found fluorine in the water:, ,.. 

 the Atlantic. I do not know on what scale he operated. But while at first I could 

 fiiid it in ten- litres of the water, afterwards, on subjecting n.c«; crystal to the vapo?» 



uld 

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