XJ,S <^N PALLADIUM. 



As 1 have already given an account * of one product ob- 

 tained from tliat ore, which I confidered as a new metallic 

 Aibftance, and denominated Rhodium, I fhall on the prefent 

 occalion conhne myfelF principally to thofe proccffes by which 

 ^ I originally detedled, and fiiblequently obtained another metal, 



to which I gave the name of PaUadium, from the planet 

 that had been dilcovered nearly at the fame time by Dr. 

 Olbers. 



In the courfe of my inquiries I have alfo exanuned the 

 many impurities that are ufually mixed with the grains of 

 plalina, but 1 (liall not think it neceffary to defcribe minutely 

 fubflances which have already been fully examined by others. 



§ I. Ore nf Iridium. 



Ore of iruiium, I muft however notice one ore, that I find accompanies (he 

 refcmblesihitof Qj-e ,)f platina, but has paired unobfcrved from its great re- 

 piatina, but »s ' ... 



infoluble in lemblance to the grains of platina, and on that account is 



nitro-muriatic fcarcely to be diftinguiQied or feparated from them, excepting 



.' by folulion of the platina; for the grains of which I fpeak 



are wholly infoluble in niiiro-muriatic acid. When tried by 



to't''ma*llelble^'''' ^^^ ^^^' '''^>' "^^^ ^^^^^^^ '^^" ^'^^ Stains of platina ; under the 

 and peculiar in hammer they are not in the leaft degree malleable; and in the 

 their frafture : fraclute they appear to confift of lamincc poffelTing a peculiar 

 luflre; fo that although the greater number of them cannot, 

 as I have before obferved, be dillinguidied from the grains 

 of platina, the laminated ftrudure fometimes occafions an ex- 

 ternal form by which they may be detefled. With a view 

 to be abfoluteiy certain that there exift grains in a natural 

 liate, which have not been detached by folution from the 

 iubltance of the grains of platina, I have feparated from the 

 mixed ore as many as enabled me to afcertain their general 

 compofition. 



much heavier Their mofi: remarkable quality is their great fpecific gravity, 



than the grains ^j^j^j^ j ^^^^.^ ^^^^^^ j^ ^^ ^^ ^^^,^ ^^ j^ ^.[^j,^ ^j^^^ ^f ^^^ 

 01 platinaj 



crude grains of plalina has not, in any experiment that I have 



made, exceeded 17,7. From thiscircuuiflanceit might naturally 



be conjedured that they contain a greater quantity of platina 



of which metal than the grains in general ; by analyfis, however, they do not 



nonU"""^^^'" appear to meto contain the fmalleft quantity of that metal, but 



* See our Journal, IV. lOT, 



to 



