432 • Effects of Explosion in Coal Mines, [June, 



with the metals, forming fluors of potassium and sodium. Under the 

 action of the galvanic battery, fluoric acid and all its compounds, 

 when moistened with water, generate the same products. The dry 

 acid accompanies ox)'gen to the positive pole, and preferring the 

 metal of the wire to that principle, unites with it, and forms fluor 

 of platinum, &c., unless the wire be oxidable, in which case it 

 forms a dry fluate. 



From these facts it appears that dry fluoric acid is neither hydro- 

 genalle nor oxygenable, but only metallalls. It is analogous to 

 the oxygenable acids, chlorine and varine, in forming dry salts, 

 except that of ammonia, which the muriatic and varic acids do not 

 form equally dry. Dry chlorate, varate, and fluate of ammonia, 

 would be resolved by heat into azote, and into chlorine, varine, and 

 fluorine, or into the acidifiable combustibles of the respective acids 

 of these salts. 



Potassium is not able to reduce the acids of the dry salts into 

 the acidifiable combustibles, because the hydrogen which watei* 

 exchanges for the metal is wanting in these compounds. 



The dry acids contain oxygen less hydrogenated than in water, 

 but more so in the oxygenable acids, than in those that are hydro - 

 genable. They are superoxidated or burnt by oxygen, as they 

 oxidate or burn hydrogen and metals ; and they superoxidate water 

 and the metaUic oxides as the acidifiai)le combustibles are acidified. 

 We acidify the suboxide of hydrogen or the oxide of this principle 

 in these bodies, without combining them with the reduced bodies 

 forming oxidated acids. With all other bodies they form salts.* 



Article V. 



Upon the dreadful Effects of the Explosion of carhireted Hydro- 

 gen in Coal Mines. From an anonymous Correspondent at 

 Newcastle. 



A.^ioNGST the many commentators upon this subject, there has 

 not fallen under my inspection the production of any (with the 

 exception of a small pamphlet by D. Nield) who has either entered 

 into the cause of its formation, or who has proposed, or even 

 hinted at a plan for removing the source of its production. Willing 

 to allow to an ingenious correspondent of the x'\.uthor of the Annals 

 of Philosophy, all the merit that is his due for an invention to pre- 

 vent accidents of this nature ; which a correspondent ^iXsAesivo,-, of 

 August 1813, expresses his earnest desire may be put in practice, 



• I hnve translated this paper a? literally as possible frnm the original Frencli ; 

 because there are several parts of it wliicii 1 do not fiilij understand. M. Van 

 Mods uses a nomenclature of his own, with llie iiaport of which I am not suflS- 

 ciently acquainted to tnm his langiftge into intelligible English. — T. 



