124 ON PALLADIUM. 



former occafion * mentioned as exhibiting a very fmgulaf 

 contratl of colours, being bright green when feen tranverfely, 

 but red in the dire(5tion of their axis ; the general afped, 

 however, of large cr)ftals is dark, brown. 



From the fait (bus formed and purified by a fecond cryf- 

 tailization, the metal may be precipitated nearly pure by iron 

 or by zinc, or it may be rendered fo by fubfequent digeftion 

 in muriatic acid. 



§ V". Rtafonsfor thinking Puiladiiim a funple Metal. 

 That palladium From the coniideration of this fait alone I thought it highly 



*/i'l ^^^l^lL probable that the lubflance ctmibincd in it with muriate of 

 ral appears iromj • _ 



pota'd) was a fimple metal, fori know o^ no inftance inchemijiry 

 its forming a of a dijiind}lj/ cryjiallized fait covtaining more than two bafes 

 t-»ili'zed iaic whh '^^''"^'*"^'^ ^'^^' ^nt acid. 1 neverlhelefs endeavoured by a fuit- 

 bafesandan able courfe of experiments to obviate all probable objections, 

 ''^' ' After examining by what acids it might be diflTolved and by 



its combinations ^,^1,3^ reagents it nrj^ht be precipitated, I combined it with 



with metals and . ° , • , , , , , n • ■ 



feparation wich- various metals, with platina, with gold, with filver, with 



out change. copper, and with lead; and when I had recovered it from its 

 alloys fo formed, I afcertained that, after every mode of tria! 

 it ftdl retained its chara6leriftic properties, being foluble in 

 nitrous acid, and precipitable from thence by mercury, by green 

 fulphale of iron, by muriate of tin, by prulliate of potafh, by 

 each ttf the pure alkalis, and hydrofulphurets, 



and its precipi- The precipitate obtained in each cafe was alfo found to be 



tation Is reduci- 1 -i i i 1 1 • 11 



bic by mere reducible by mere heat to a white metal, that, except m very 

 heal. fmall quantities, could not be fufed alone by the blowpipe, but 



could very readily be fufed with fulphur, with arfenic, or 

 with ph(;fj)horus, and in all other refpefts refembled the 

 original metal. 

 Qa. Whether it The only hypoihefis, on which I thought it poflible that I 

 ^'4^* ^^^*//_ could be deceived, arofe from the recoUeaion of the error, 

 «4»cid? which fubftlted for a few years, refpc61ing tlie compound 



formerly called fiderite. It was poflible that fome metallic or 

 other fixed acid might unite too intimately with either a known 

 or an unknown metal to be feparated by the more common 

 fimple a(Iinitie>. I confequently made fuch attempts as ap- 

 peared beli calculated to difunile a compound lo conllituled. 



* Phil. Trans. ISOI, p. 428. 



Having 



