172 On a new Metal, found in cridh Platina. / 



tried, excepting mercury; and with gold or silver it forms 

 very malleable alloys, tliat are not oxidated by a high degree 

 of heat, but become incrnst^'d with a black oxide when very 

 slowly cooled. 



(E 5.) When 4 parts of gold are united with 1 of rho- 

 dium, although theallovmav assume a rounded form under 

 the blowpipe, yet it seems to be more in the state of an 

 amalgam than in complete fusion. 



(E (5.) When 6 parts of gold are alloyed with- 1 of rho- 

 dium, the compound may be perfcctiv fused, but requires 

 far more heat than fine sold. There is no circumstance in 

 which rhodiuni diflcrs more fromplatina, than in the colour 

 of this alloy, which might be taken for fuiegold, by anv one 

 who is not very much accustomed to discriminate the dif- 

 ferent qualities of gold. On the contrary, the colour of an 

 alloy containing the same proportion of platina, differs but 

 little from that of platina. This was originally observed by 

 Dr. Eewis. "The coloijr was still so dull and pale, that the 

 compound (5 to 1) could scarcely be judged by the eye to 

 contain any gold*." 



1 find that palladium resend)les platina, in this property of 

 destroying the colour of a large (juantitv of gold. When 



1 part of palladium is united to 6 of gold, the alloy is nearly 

 white. 



(E 7.) When I endeavoured to dissolve an alloy of 

 silver or of gold with rhodium, the rhodium remained un- 

 touched by either nitric or nitro-murialic acids: and, when 

 rhodium had been iused with arsenic or with sulphur, or 

 when merely heated by itself, it was reduced to the same 

 state of insolubility. But when 1 part of rhodium had been 

 fused with 3 parts of bismuth, of copper, or of lead, each of 

 these alloys could be dissolved completely, in a mixture of 



2 parts, bv measure, of muriatic acid, with 1 of nitric. 

 With the two former metals, the proportion of the acids to 

 each other seemed not to be of so nuicb consequence as with 

 lead; but the lead appeared on another account preferable, 

 as it was most easily separated, when reduced to an in- 

 soluble nmriate bv evaporation. The nmriate of rhodium 

 had then the same colour and properties, as wh.en formed 

 from the yellow oxide precipitated from the original salt. 



(E 8.) The specilic sravity of rhodium, as far as could 

 be ascertained by trial on so small quantities, seemed to 

 exceed 11. That of an alloy consistimi;, of 1 part rhodium 



• I.'-'wis's Philo^Oiihicl Commcrcq of Arts, p. 526. -■ 



and 



