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Se&. 228. INFLAMMABLE SUBSTANCES. 437 fording different fubftances, are here confidered as being levi.ye them, and the dephlogijticated air is found ip the receiver. The precipitate per fe of Mercury, if revived in t'e fame manner, gives another indance of this truth. If phlogifton alone, fays he, could pafs through the retort, there uould not be found the empyreal air in the receiver, and the ignoble metals might be all’o revived in the fame manner. I do not fee, I mud confefs, that Mr. Scheele has pointed out any reafon, why the ignoble nutals fhopld pot be reduced or revived likewjfe, from their calces, by the phlogifton, con- ^ Cat t * 1,t P a ^ es through the retort; and as to * *i iP ^ 0 S' l f tlcute ^ air he Ipcrtks of which is found after the re u ion of thofe noble mttals, it.may have been combined with their calces, before they wore put into the retort. Mr. Kirwan, m his Notes to this Treatife an Fire, from which this luminary tw ^ 1 a’ y3 ’ Ift ’ that in no in{h,nce tlu « it appear ™t f g l Penetrates tllro ’ J gh glafs, much lefs a com pound of fmt air and pblogifon ; and 2 dly, that if Mr. bchedc s notions were true, then other metallic calces, or at Jeait black manganefc, would be reduced by bare heat; for this calx dephlogifticatcs nitrous acid, and therefore has a' Wronger alhmty with phlogifton than this acid, as Bergman atnrms: heat therefore ought as well to be dccompoled by it, nit ‘°'^ acac1- This lift objeftion can haully be aniwer- aoie out^by Tome unknown property bf the mangnnefe, which is 110 aniwcr at all. But in regard to the lird, manv combina tions are known of two or more fubftances that pafs through ocieS, which would dop each before they were combined; h u iat Mr, Scheele has faid 011 the nature of li?kt t phlorij} 0 pr ° VC ’ ^ lat ' s l 10 t always tpiitc impervious to accorc ->ng to Scheele, is a compound, containing p) ogijtcn and heat, from which both may leparaie themfeives in proper circumdances'. A dilution of filvcr, by nitrous acid, mixed with chalk, and expofed to the iim-fhine, is revived into a metallic form by the phlogifton of light. Nitrous acid a o in a glals veilel, receives phiigifton from light, and be- comcs of an orange colour; but if the glafs be painted black, I ; f 3 the
