424 Dr. Clarke upon the Gas Blowpipe, [June, 



• 17* The beautiful iridescent crystals which form in the aqueous 

 solution of the muriates obtainea by dissolving crude platina in 

 nitromuriatic acid ; and after the precipitation of ptatinum by 

 muriate of ammonia y are easily reduced to the metallic state upon 

 charcoal by the flame of the gas blowpipe. The metal so 

 obtained is perfectly malleable, and has all the characters of 

 platinum; excepting that it is almost insoluble in nitromuriatic 

 acid, even when this acid is in a boiling state ; owing, probably, 

 to a small portion of iridium with which the platinum is conta- 

 minated. 



8. The prussiate of palladium obtained by the precipitation of 

 this metal hy prussiate of mercury, may be decomposed, and the 

 pure palladium revived upon charcoal, with all the whiteness of 

 silver, and made perfectly malleable. This last experiment with 

 the gas blowpipe is remarkable for the beautiful sapphire-blue 

 colour with which the flame is tinged during the revival of the 

 palladium. It affords, moreover, one of the easiest processes for 

 obtaining small specimens of pure palladium to which the che- 

 mist can have recourse. All that is necessary is briefly this : 

 Dissolve crnde platina in nitromuriatic acid; evaporate to dry- 

 ness ; add distilled water ; precipitate the platinum by muriate 

 of ammonia ; filter the supernatant solution ; precipitate jorMsszafe 

 of palladium by prussiate of mercury, and collect the precipitate 

 upon a filter. Now make this filter containing the precipi- 

 tate into a pellet, and expose it upon charcoal to the flame of 

 the gas blowpipe. The result will be a malleable bead of the 

 purest palladium, coated over with blue glass from the silicated 

 alkali of the paper filter, which separates from the metal upon 

 the first blow of a hammer. Glass will also appear in all experi- 

 ments for the revival of metals where filters have been thus used. 

 It is, perhaps, a similar result to the glass which remains after the 

 combustion of bank-paper notes. 



9. The revival of the salts and oxides of the four metals obtained 

 from arenaceous |?/a^mz/w; namely, iridium, osmium, palladium, 

 and rhodium, whether as alloys, or as pure metals, afford some 

 of the most curious and amusing experiments with the gas 

 blowpipe. The last experiment with these metals which I 

 shall now describe relates to the revival of rhodium from its 

 oxide, as obtained in the following manner: After the solu- 

 tion of crude platina in nitromuriatic acid, having preci- 

 pitated platinum by muriate of ammonia, and palladium by 

 prussiate of mercury ; also iron by -prussiate of potass, immerse a 

 clean plate of z^wcmto the filtered liquor, and leave it for several 

 hours. A precipitate will fall of a brownish-red colour, which, 

 when dry, is black. Before the gas blowpipe, the filter, con- 

 taining this precipitate, exhibits a sort of coruscation, like a 

 little firework ; but at length a slag will remain on the charcoal 

 of an iron-brown colour, containing within it a bead of a silvery- 

 white metal. This metal is harder than wrought iron. It was 



