202 °^ TH E P^ L ^ 0^ V-OLtA. 



moift becomes white, which is fimilar to the experiment with 

 mercury, in which the black powder of this metal, produced 

 by the agitation of it in water, becomes white running mer- 

 cury as it becomes dry, diminifhing and phlogifticating the 

 air in which it is confined. 

 Experiment to The black calx of filver, made by its folution in nitrous 



black ^owder of ac5c1, is faid b ^ v Mr * Macc l uer > in nIs Dictionary, to be owing 

 filver, treated to the phlogifton contained in that acid. To afcertain this, I 



by nitrous acid, diirolv r ed fome pure filver in fpirit of nitre, and evaporating 

 contains no oxi- , r , . ' , , , , -. ... r 



«en. the lolution, I heated the reiiduum in thirteen ounce meaturcs 



of dephlogifticated air, of the ftandard of 0.82, with two equal 

 quantities of nitrous air, by which it was reduced to eleven 

 ounce meafures, of the ftandard of 1.72, with one meafure of 

 nitrous air ; fo that it was almoft wholly phlogifticated air. 

 Confequently this calx of filver contains no oxigen. 

 Theory. That My prefent opinion concerning the theory of this curious 

 of" the z'mcdiere P roce ^ s » s as follows. Since the operation wholly depends on 

 are plus and the calcination of the zinc, which futTers a great diminution oT 

 minus dates of weight while the filver is i ittIe a ff e aed, and all metals lofe 

 phlogifton pro- ... . . ... 



duced in the ap- their phlogifton in calcination, what remains of the zinc in a 



P n at, -A an . dthat metallic form in the pile, and every thing connected with that 

 ele£ric"!ty, or en( l of it, is fupcrfaturated with phlogifton, while the calcined 

 nearly fo. part, and every thing connected with that end of the pile, is 



deprived of it. The former, therefore, is in a pofitive ftate, 

 and the latter in a negative one, with refpect to phlogifton ; 

 and it feems to follow from thefe experiments, that this is the 

 fame thing with pofitive and negative electricity ; fo that the 

 eje&ric fluid and phlogifton are either the fame, or have fome 

 near relation to each other. The filver feems to a6t princi- 

 pally as a conductor of electricity ; for the furface of it is only 

 blackened in fome places in this procefs, in confequence pro- 

 bably of receiving phlogifton from the zinc ; but the water is 

 moil elTential to it, becaule it constitutes the principal part, if 

 not the whole, of the addition of weight in the calx. Ac- 

 cordingly, in the calx of zinc I have found nothing but water, 

 though it is probable that there is a fmall portion of oxigen 

 in it. 

 or two electric Thefe experiments favour the hypothefis of tzvo eleclric 

 Jod dS hlo X ifton. fi uids > tlie P^ntive containing the principle of oxigen, and the 

 negative that of phlogifton. Thefe united to water feem to 

 conftitute the two oppolite kinds of air, viz. dephlogifticated 

 and inflammable. 



Thefe 



