the Attractive Powers of Mineral Acids. 55 
With regard to mercury, the experiments of Mr. bayen 
are well known : he has (hewn that vitriol of lead and fub. 
corrofive can be deprived of no more than half of their acid 
even by cauflic fixed alkalies, 3 roz. 293. 
Again as to lead, if perfedllv dry common fait be pro- 
jected on lead heated to incandefcence, the common fait will 
be decompofed, and horn lead formed, 1 margraf. 33 and' 
38. Nor can this be attributed to the volatilization of the acid 
by heat ; for the alkali is as fixed as the lead, and muff there- 
fore be caufed by the greater affinity of the calx of lead, to 
which, when dephlogifficated, the acid can unite. Mr. scheele 
informs us, that if a folution of common fait be digeffed with 
litharge, the common fait will be decompofed, and a cauflic 
alkali produced, scheele on Fire, p. 175. He alfo decom- 
pcfes common fait by fimply letting its folution (lowly pafs 
through a funnel filled with powdered litharge. * Mr. tur- 
ner daily decompofes common fait by means of litharge. Mr. 
sciieele alfo decompofes marine felenite, by means of litharge, 
through fimple mixture, without the affiftance of heat, and 
the calcareous earth is feparated in a cauflic (late ; which (hews 
that this lalt is decompofed by the fingle luperior affinity of 
the metallic calx to the marine acid, scheele on Fire, p. 174.. 
That acids have lefs affinity to volatile alkalies than to feve- 
ral metallic fubflances appears in fundry inflances. Horn filver 
is foluble in volatile alkalies, as is well known. Now, if this 
folution be triturated with four times its weight of mercury, 
the marine acid will combine with the mercury, and not with 
the volatile alkali ; for a mercurius dulcis , and not a fal ammo- 
niac, will be formed, as Mr. margraf has (hewn, 1 margl 
286. If two parts fal ammoniac and one of filings of iron be 
* scheffer Chymifche Foceles, § 59. 
triturated- 
