AXJTIdK OF PLAtmA AND KtERCURY* 4^9 



JExp^lV, ^Ontz of the mod delicate tefts that I have obferved Exp. 9. Recent 



Sn chemiftry is recent muriate of tin, which deteflsf the pl'e- JJg'^J^oft**(jgji'"aJe 



fence of the fmBileft portion of mercury. When a fingle drop teft of mercury. 



dF a faturate folution of neutralized nitrate or muriate of i';'°" "°^^*"fj" 



. cate the mercury 



mercury is put into 500 grains of water, and A few drops of a in a mixed foiu- 

 faturate folution of recent muriate of tin are added, the liquor ^'O" oj ^^^^ ^^' 

 becomes a little turbid, and of a fraoke-gray colour* If thefe 

 600 grains of liquid be diluted With ten times their weight of 

 water, the effeft is of courfe diminilhed, but ftill it is per- 

 ceptible. I had on a iformer occafion ohferved the adion of 

 recent muriate of tin upon a folution of plalina. If a folutiort 

 of recent muriate of tin be poured into a mixed folution of 

 platina and mercury, not too concentrated, it can hardly be 

 diftinguiflied from a fimple folution of platina. But if too 

 fouch mercury be prefent, the excefs is a6led upon m mer- 

 cury ; and the liquor aflumes a darker cobur than with platina 

 \alone. • 



From all thefe experiments It is evident thfit mercufy can Hence, i, j. 

 a£l upon platina, and confer upon it the property of being pre- f^'^tma prote£^s 

 cipitat^d in a rpetallic ftate by green fulphate of iron. By nitric acld^ and 

 Experiments 1 and 2, it is proved, 1ft, That platina can proted mercury renders 

 d confiderable quantity of mercury from the adion of nitric ig^^ ^^ nitro-^ 

 acid ; and i^dly. That mercury can increafe the adlion of nitro- mur. acid : 

 muriatic acid upon platina. From Experimenis 3, 4, 5, 6, 7, 8, ? e^fn s m e'r "u^ry 

 it appears that mercury can combine with platina in fuch a in the ftrong 

 tnanner as not to be feparated by the degree of heat nfeceflary 8^^L°^^"!^°"' . 

 to fufe the compound j fince after the fufion it retains that |)latinaaaoii 



property, which is effentially charadleriftic of the prefence of "*^^ other in fa- 

 . ri. ^1. rr„,,r. .. ""^ compofitjoni, 



mercury in a iolution ot platina. I he 8th Experiment proves 9. piatina de- 



that the action of mercUry upon platina is not confined to the fends mercury ia 



metallic l^ate*, but that thefe metals can combine and form an being rcduc&d W 



ihfoluble triple fait With an acid which produces a very foluble ™» of tin* 



compound with platina alone. The 9th Experiment fliowsthat 



J)latina can retain in folution a certain quantity of mercury, 



arid prevent its redudlion, by ,a fubftance which a6ls moft 



powerfully to that effect, when platina is not prefent. That 



part of the general pofition therefore which is the objed of 



this paper is proved, if thefe experiments, upon being repeated 



by other chemifts, (hall be found to be accurate. 



One or two of the above experiments feem to be in contra- Remark on jnl- 



di€lion lo fome that I iiave flated in my paper upon palladium ;^^^"*"** 



N2 for 



