io NATURAL HISTORY ^NORWAY. 



out. Then turning the cock fo as to re- admit the air gently into 

 the globe during its motion, the light was broken and interrupt- 

 ed, diminifhing gradually, till at lafl it appeared only on the out- 

 fide of the glafs, where it was accompanied with attra&ion. 

 Does it not appear that the external air, by its eledricity, at firft 

 drives back the eledric effluvia of the glafs, which go then to 

 the infide of the globe, where there is the leaft refinance? For 

 we obferve that as the air comes in, it repels the electric effluvia, 

 that go inwards no longer when all the air is come in. If the 

 fact be fo, as the experiment fhews, is not my conjecture proved, 

 viz. that the air is electrical? 



In the reverend and learned Dr. Hales's Vegetable Statics, 

 feveral of his experiments mew, that air is abforbed, and lofes its 

 elafticity by the mixture of fulphureous vapours, fo that four 

 quarts of air in a glafs-vefTel will, by the mixture of thofe efflu- 

 via, be reduced to three. Will not this phenomenon be ex- 

 plained by the different electricity of fulphur and air? The efflu- 

 via of fulphur, being electric, repel one another : and the particles 

 of air, being alfo electric, do likewife repel each other. But the 

 air being an electric of a vitreous electricity, and fulphur of a reft- 

 nous electricity, the particles of air attract thofe of fulphur, and 

 the Molecule compounded of them, becoming non-electric, lofe 

 their repulfive force." 



The judicious reader may, of himfelf, apply this pafTage to the 

 north-light ; and perhaps, by a mature difcufllon of it, ftrike out 

 clearer ideas of that phenomenon, than I can develop, who only 

 undertake to fet down a few things, which have occurred to me. 



The terreflrial globe, together with its atmofphere, may be 

 confidered as the glafs-globe of the electrical machine. Upon 

 the air being exhaufted, and the globe whirled about with velo- 

 city, there appears within it a purple flame, and this is the co- 

 lour of the north-light ; now this flame muft be the asther igneus. 

 Upon the re-admiflion of the circumambient air, efpecially if thick 

 and damp, the acid or ethereal fire within is expelled, and ho- 

 vers for fome time on the upper furface of the glafs, till, mingling 

 with the air, it is diffrpated, and extinguished. Now this feems 

 to intimate to us, that the north-light obferved towards the pole 

 or axis of our earth, does not only owe its origin to the ether, 

 but is the very ether itfelf ; which, being aggregated, gives way to 



the 



