J78 ' PRETENDED NEW METAL; PALLADIUM. 



4th. That mercury has an affinity for copper, for lead, and 

 for arfenic. 



This feries of experiments is not intended as a fyftem of 

 metallic affinities ; but as a few fa6ls ftated to corroborate an 

 aflertion. I am well aware that many others might be noticed ; 

 but it is not my intention to enter further into this fubjed, in 

 the prefent paper. The general importance of the principle, 

 and the extenfive influence it is likely to have upon chemiftry, 

 demand that it fliould be treated by multiplied refearches. 

 The experiments that can elucidate it are of the mofl delicate 

 nature, and require peculiar care; for they do not always 

 fucceed, unlefs performed under the mod favourable circum- 

 flances. 

 Mixed folutiona When mixed folutions of three or more metals are expofed , 

 ^wo'^metat'L ^^ ^^^^ ^dion of recent muriate of tin, or of green fulphate of 

 more ftriking iron, their a6lion upon each other appears in a much more 

 *"e^xr°'^^ ^°"^' ^"^i"g* as alfo in a much more complicated point of view. 



EXPERIMENTS UPON PLATINA. 



Ixp. on platina. I ffiall now (late fome experiments which I have had occaiion 

 to make upon platina, during the foregoing refearches. Very 

 little is known concerning this metal, its oxides, or its falts; 

 and, although I have not had occaiion to extend the enquiries 

 very far, yet my experiments may ferve to eftablifti a few 

 points. 

 Platina diflblved I diflblved a quantity of puriHed platina* in nitro-muriatic 

 ^Tlri'^V'''"^' acid, and precipitated by lime. A great portion of platina 

 nitric acid } the remained in the liquor, although I had ufed an excefs of the 

 acid expelled above earth. I rediflblved the precipitate in nitric acid, and 

 by heat; oxide evaporated to drynefs. The refult was, a fubrtitrate of platina. 

 reduced by f then expofcd the mafs, in a crucible, to a heat capable of 

 Hinpeig 1 . g^pgiijpg the acid altogether ; and the oxide remained alone. 

 When this was reddened, at a heat which certainly was not 

 capable of melting filver, the oxide was reduced, and ap- 

 peared with a metallic luftre. The weight of the various* 



* By purified platina, I have always underftood, in this Paper, 

 platina reduced, at a gentle heat, from the fait obtained by pouring 

 a CO! centrate folution of muriate of ammonia into a concentrate fo* 

 lution of platina. 



produ^ 



