184 Inquiry into the 'Latv: if jiJiiiUy, 



oxigen, fo that their rcfulting affinity for the fubftances that are alfo greatly oxigenated it 

 very weak ; but the mariatic acid which appears to liave in its conftitution only a very fmali 

 proportion of oxigen, ought to have a much greater difpofition to combine with oxigenated 

 fubftances. 



7. In the preceding obfervations I have fuppofed, that the different alkalis fhare the acid 

 of a metallic folutioti with the oxide which is precipitated. I do not here fpeak of preci- 

 pitates by ammonia, which in fome circumftances is decompofed, and by that means 

 changes the conftitutiqn of the precipitate, as has been particularly fliewn by Fourcroy ; 

 but this property is fubjeft to modifications which demand particular attention. 



The experimeuts of Bayen have afcertained beyond a doubt, that the precipitates of mer- 

 curial nitrates and muriates retain a greater or lefs portion of acid, fo that on expofing the 

 precipitates of the mercurial nitrate to a fufficient heat, fome nitrous acid is difengaged ; 

 and on making the fame experiment on the precipitates of mercurial mbriate, a greater or 

 lefs quantity of infoluble mercurial muriate is fublimed. I fliall here add fome obfervations 

 to thofe I have already made, {rnquirics. Art. XIII. No. i.) 



When the oxigenated muriate of mercury is decompofed by the precife quantity of car- 

 bonate of foda, which is neceflary to effe£t its precipitation, the precipitate contains mu- 

 riatic acid, carbonic acid, and oxide of mercury in excefs ; fo that on expofing the preci- 

 pitate to the aflion of heat, carbonic acid gas and oxigen gas are difengaged ; nearly half 

 the mercury is reduced to metal, and the reft of the precipitate is fublimed, retaining all 

 the muriatic acid which remained in combination with the oxide, and forming the mercu- 

 rial muriate obferved by Bayen. The liquid fupernatant over the precipitate affords by 

 evaporation, at flrft' carbonate of foda, and afterwards a triple fait in which foda predo* 

 minated. 



The carbonate of pot-afh prefents different phenomena. A very fmall portion only is ne- 

 ceffary to produce a total precipitation in the folution of corrofive mercurial muriate, and 

 the precipitate obtained does not amount to half the weight of what would be given by the 

 fame quantity of oxigenated muriate of mercury, precipitated by the carbonate of foda. 

 This precipitate, expofed to the a£lion of heat, gives out carbonic acid, and fublimes almoft 

 totally in the ftate of mercurial muriate, with the leaft portion of acid ; a very fmall portion 

 only refumes the metallic ftate. The liquid that covers the precipitate makes no effervef- 

 cence with the acids ; fo that here the whole of the carbonic acid is combined in the preci- 

 pitate with the oxide, and a portion of muriatic acid nearly double that contained in the 

 precipitate by carbonate of foda. The liquid when evaporated affords a triple fait much 

 more foluble in water than the oxigenated muriate of mercury : this fait cryftallizes in filky 

 needles. 



The carbonate of ammonia caufes an effervefcence on decompofing the corrofive mer- 

 curial muriate, and no acid is found either in the precipitate or in the fupernatant liquid. 

 The weight of the precipitate conftitutes nearly five fixths of the muriate decompofed; a 

 difengagement of ammonia takes place on the addition of lime. When urged by heat, thq 

 ammonia is decompofed, and azote gas only is received. All the mercury is fublimed with- 

 4 out 



