thz Laws of Affinity. 525 



bf tFiefe intermediate combinations differ fo much as to leave 

 no room for the determination of their particular properties, 

 unlefa both the degree of oxydation and the proportion of the 

 acid be known. 



What I now obferve as to the intermediate degrees of ox- 

 idation mult alfo be applied to the other metallic falts, fucli 

 as the fulphate of iron, in which there are likewiie only two 

 fixed terms, that of the weakeft and that of the itrongeft ox* 

 idation. 



4. Bergman had before difcovered that a folution of mer- 

 cury by the nitric aeid made in the cold, has different pro- 

 perties from that which is prepared by means of heat; and, 

 in his excellent treatife on the analvfis of waters, he remarks, 

 that the former docs not lb readily afford a precipitate with 

 the folutions which contain fulphuric acid, and that the pre- 

 cipitate it forms is white, whereas that of the folution made 

 with heat is yellow ; that the firlt then forms mild fulphate 

 of mercury, which is white, and more foluble in water than 

 the oxygenated fulphate, while the latter forms the oxygen- 

 ated fulphate* 



When nitrate of mercury is prepared by means of heat, 

 fome nitrous gas is at firft difengaged ; but when the difen- 

 gagement is complete} the mercury is perceived to be dif- 

 lolved, with the production of fcarccly any nitrous gas. I 

 am indebted for this obfervation to C. Gav, a young chemift 

 of the Polytechnic School, who adds much fagacity to confi- 

 derable zeal. We fee, therefore, that by means of heat an 

 oxygenated nitrate is formed, which, if the operation be not 

 flopped, afterwards combines with mercury, as in another 

 operation the oxygenated muriate of mercury combines with 

 a frefh quantity of this metal *. But in the fluid nitrate of 

 mercury, there are no determinate proportions between the 

 mercury molt oxygenated, and that leaft fo : it appears that 

 all the intermediate proportions may exift, as I have obferved 

 with refpeet to the fulphates. 



When nitrate of mercury is precipitated by muriate of foda, 

 mercurial muriates are obtained, which dirfcr according to the 

 oxidation of the mercury. With the nitrate a little oxided 

 a white precipitate is obtained, which retains a part of the 

 nitric acid, arid cannot be diffolved in the muriatic acid, nor 



* Fourcrov has mown that the oxygenated fulphate of mercury, fub- 

 mitted to ebullition with watfcr and mercury, a£ts alfo upon the metal; it 

 mutt therefore pafs to the ftate of mild fulphate. The corrofive mercurial 

 muriate, when dilfolvcd in water, does not aft upon mercury; but by tri- 

 turation with mercury without water, it begins to combine with it, and to 

 impart its oxygen : the combination becomes uniform by fublimation. 



X z bs 



