1S21.] Dr, Clarke upon the Gas Blowpipe, 425 



also brittle. I endeavoured to dissolve the slag containing itby 

 boiling it in caustic potass, but could not succeed. Afterwards 

 I added nitromuriatic acid, and having evaporated the acid to 

 dryness, there remained a rose-coloured salt. Still the bead of 

 metal remained chiefly undissolved. I then fused it with suU 

 phiTy and expelled the sulphur on charcoal by the common blow- 

 pipe. Still the metal was brittle. I then tried to cupel it upon 

 pipe-clay with borax ; it was infusible ; but it communicated a 

 broion, and afterwards a black colour to the borax ; which are 

 the hues of the deutoxide and protoxide of rhodium. The metal 

 also in these experiments always became black by heat ; which 

 is another character of rhodium. By mixing together dry caustic 

 potass and borax, in equal parts, I found I could hold it in 

 perfect fusion upon charcoal before the common blowpipe, and 

 distinctly discern the minute globules of metal separating in the 

 boihng flux. Still the result, when cold, was brittle, and quite 

 black. I then boiled it again in 7iitromuriatic acid, and by eva- 

 poration to dryness had a beautiful rosi/ muriate. Afterwards I 

 added the acid once more, in a dilute state, with common salt. 

 The rosy soda muriate appeared as it became dry. I washed the 

 residue repeatedly with alcohol, and dried it. Distilled water 

 was then added, and the solution, by gentle heat, being evapo- 

 rated to dryness, the rosy-coloured soda-muriate appeared as 

 before ; but in less quantity. These experiments were con- 

 ducted upon a bead of metaflic rhodium, revived from its oxide 

 before the gas blowpipe, the weight of which originally could hardly 

 have equalled 1-lOthof a grain. When the oxfcife has been obtained 

 in greater quantity, nothing more is necessary for its revival, 

 than to mix it with oil, and expose it upon charcoal before the 

 flame, which should be made to act vertically upon the oxide by 

 means of a bent tube. 



The experiment is beautiful, owing to its simplicity, to the 

 facility with which it may be conducted, and to the curious 

 result which follows it ; namely, the revival of metallic rhodium, 

 exhibiting all the whiteness and lustre of the purest silver, and 

 being perfectly [malleable. This experiment was attended with 

 more than usual success on Saturday, May 12, when it was 

 pubhcly performed in my lecture room in Cambridge, The 

 black oxide of rhodium, precipitated from its solution by zinc, 

 was mixed in the form of powder with oil, and exposed, upon 

 charcoal, to the flame of the gas blowpipe. It was first melted 

 into a black slag ; then into a brittle white regulus, which, by 

 continuance of the heat, became a bead of metal as white as the 

 purest silver. It then began to burn, like platinum, with scin- 

 tillation ; and the flame of the burning metal was tinged with a 

 fine emerald-green colour ; proving that one of the oxides of 

 rhodium may have the same hue. The bead of metal was then 

 placed upon an anvil, where it sustained the shocks of a large 

 hammer ; and was finally extended and flattened in its form. It 



