Inquiry into the Laivs if Affinity. 1,8 1 



according to the quantity of acid that the firft combination had retained ; a. according tO' 

 the quantity of water employed ; 3. according to the temperature j for the heat concurs 

 with the a£tion of the water. 



If inftead of fimple water, an alkaline folution be employed, which exerts a more powers 

 ful a£tion upon the acid than pure water, two different combinations are formed, one o£ 

 which is found to be almoft intirely the oxide, and the other in which the acid is for the 

 mod part engaged : the precipitate then afforded differs principally from that which water, 

 alone would have produced, by the fmaller proportion of acid which it retains, and which, 

 depends on the degree of concentration of the alkaline liquor which ads upon it. 



When the oxigenated fulphate of mercury has preferred a more confiderable excefs of 

 acid, the a£lion of the acid may be fo weakened by the wafer, that no feparation will be 

 made. 



3. I have hitherto fuppofed, that there were but two fulphates of mercury, one with the 

 fmallefl; poffible proportion of oxigen, and the other with the greateft proportion ; but it is 

 manifeft that there are but thefe two extremes that are fixed, fo that they may contain within 

 their limits all the other degrees of oxidation : the properties of thefe intermediate combir 

 nations differ fo much as to leave no room for the determination of their particular proper- 

 ties, unlefs both the degree of oxidation, and the proportion of the acid be known. 



What I here obferve as to the intermediate degrees of oxidation, muft alfo be applied to 

 the other metallic falts, fuch as the fulphate of iron, in which there are likewife only two 

 fixed terms, that of the weakeft and that of the ftrongeft oxidation. 



4. Bergman had before difcovered, that the folution of mercury by the nitric acid made 

 in the cold, has different properties from that which is prepared by means of heat ; and in 

 his very excellent treatife on the analyCs of waters, he remarks, that the former does not 

 fo readily afford a precipitate with the folutions which contain fulphuric acid, and that the 

 precipitate it forms is white, whereas that of the folution made with heat is yellovv; that 

 the firft then forms mild fulphate of mercury, which is white, and more foluble in water 

 than the oxigenated fulphate, while the latter forms the oxigenated fulphate. 



When the, nitrate of mercury is prepared by means of heat, fome nitrous gas is at firft. 

 difengaged, but at a certain period, when the difengagement is complete, the mercury, is 

 perceived to be diffolvqd, with the produftion of fcarcely any nitrous gas. I am indebted 

 for this obfervation to Citizen Gay, a young chemift of the Polytechnic fchool, who adds 

 much fagacity to confiderable zeal. We fee therefore, that by means of heat an oxigenated- 

 nitrate is formed, which if the operation be not ftopped, afterwards combines with mercury 

 as in another operation the oxigenated muriate of mercury combines with a frefli quantity 

 of this metal *. But in the fluid nitrate of mercury, there are no determinate proportions 



• By an obfervation of Fourcroy it is ftiewn, that the oxigenated fulphate of mercury fubmitted to ebul- 

 liticn with water and mercury, a£ls alfo \ipon the metal : it muft therefore pafs to the (late of mild ful- 

 phate. The corrofive mercurial rnuriate, when diflblved in water, does not aft upon mercury ; but by tri- 

 turation with mercury without water, it begins to combine with it, and io impart its oxigen : the combina- 

 %QH becomes uniform by fubliniationi 



betweejOi 



