the Laws of dffinlty. 327 . 



pitate obtained docs not amount to half the weight of what 

 would be given by the fame quantity of oxygenated muriate 

 of mercury, precipitated by the carbonate of ioda. This pre- 

 cipitate, expofed to the action of heat, gives out carbonic 

 acid, and fublimes almolt totally in the Hate of mercurial 

 muriate, with the lead portion of acid; a very fniall por- 

 tion onlv refumes the metallic itate. The liquid that covers 

 the precipitate makes no eflervefcence with the acids; fo that 

 here ihe whole of the carbonic acid is combined in the pre- 

 cipitate with the oxide, and a portion of muriatic acid nearly 

 double that contained in the precipitate bv carbonate of foda. 

 The liquid when evaporated affords a triple fait much more 

 foluble in water than the oxygenated muriate of mercury : 

 this fait cryftallizes in fdky needles. 



Carbonate of ammonia caufes an efTervefcence on decom- 

 pofing corrofive mercurial muriate, and no acid is found either 

 in the precipitate or in the fupernatant liquid. The weight 

 of the precipitate confhtutes nearly five-fixths of the muriate 

 decompofed ; a difengagement of ammonia takes place on 

 the addition of lime. When urged by heat, the ammonia is 

 decompofed, and azote gas only is received. All the mer- 

 cury is fublimed without reduction. But in this fublimate 

 the mercury cannot be as much oxided as in the fublimation 

 of precipitates obtained by the fixed alkalis or lime, a part of 

 the oxygen having gone, decompofes the ammonia. The 

 liquid which covered the precipitate contained a combination 

 of oxide of mercury, of muriatic acid, and ammonia. 



The precipitation by ammonia prefented the fame pheno- 

 mena, except the etTerveicence. 



8. By attending to the other metallic folutions and preci- 

 pitations, the character of thofe of mercury are earilv diico- 

 vered, as well as the modifications which depend on the par- 

 ticular affections of each oxide : i therefore think we are juUi- 

 fied in (rating the following principles: 



1 . Acids act upon metallic oxides as upon other fubftances, 

 in proportion to their mals ; for when a metal has become 

 but little foluble or infoluble, it may be dhTolved bv an excels 

 of acid, or may form, by means of fuch excels, a more dui% 

 able combination. 



2. When a metallic combination is decompofed, the alkali 

 or alkaline earth made ufe of, produces a divmon of the jcid 

 in proportion to the energy of it- a&iou When the metallic 

 combination is weak, water is fuffi ieni t< decompose it; 

 falts with cither a maximum or minimum of acid are then 

 formed. In this cale the metallic oxides fottow the fame 

 Uuys as other i'ubftuncesj but it iomaimes happens that the 



X4 . alkarUuo 



