1817.] On the Decomposition of the Earths. 199 
were present at these experiments, himself beat out the rhodium, 
which had been obtained in form of a globule, into a thin circular 
lamina of the metal. 
4, Soda-Muriate of Iridium and Osmium.—I suppose this salt to 
be a soda-muriate. It was found in the chemical laboratory by 
Professor Cumming, in the form of a black powder resembling that 
of plumbago, and was contained within a small phial which the late 
Professor ‘Vennant had labelled “ Jridtwm and Osmium.” My 
reason for particularly noticing it is this; that it contains the most 
infusible body 1 have ever met with. When exposed to the action 
of the ignited gas, brilliant metallic globules are dispersed upon the 
charcoal used as a support, and a brownish angular residue is left, 
unreduced, which sustains no change, nor even alteration of form, 
or colour, by any further continuance of the heat. 
5. Ore of Iridium and Osmium in Grains.—Some of these grains 
being placed in a charcoal crucible, were fused with difficulty into 
one globule; a combustion of the iridium taking place the whole 
time ; accompanied by an evident volatilization. The globular 
residue was afterwards flattened upon an anvil by severe shocks of a 
hammer. The metal however proved to be so exceedingly hard 
that it was only partially extended by this pressure. I afterwards 
endeavoured to file it; but the sharpest Carron files would scarcely 
touch it. Constant friction during 30 minutes was necessary to 
disclose an even surface of metal. It then exhibited a very high 
degree of metallic lustre; inferior only to that of palladium alloyed 
with nickel. 
6. Alloy of Silicium and Iron.—This alloy is easily obtained, by 
placing a bead of pure silex, after fusion, into contact with a bead 
of pure iron of equal bulk, ina charcoal crucible, and fusing them 
together. The iron, at this exalted temperature, takes all the 
oxygen of the silex, and a white metal is developed, consisting 
almost wholly of siliciwm, combined with a little iron. The colour 
of the alloy resembles precisely that of pure siliciwm obtained by 
the reduction of the earth. 
7. Reduction of Wood Tin and Barytes.—I have placed the re- 
duction of these two substances together, in order to exhibit, by 
an easy analogical process, the decisive evidence thereby afforded of 
the metallic base of barytes, and its developement, when the pure 
earth is exposed, per se, to the action of the ignited gas. This 
takes place equally, whether the s/ag of Larytes be supported by 
forceps made of slate, porcelain, pipe-clay, or of iron. For the 
sake of noticing the nature of the deposit made upon polished iron, 
by the two substances which were the subject of the experiment, 
iron forceps were employed in the present instance. The forcible 
analogy of the results cannot fail to strike the attention of every 
chemist. In both trials the coloured flame seems immediately to 
recede the revival of the metal. 
(A.) Wood Tin.—Fusion—deposition of a white oxide on the iron 
forceps—violet-coloured flame—scintillation, denoting combustion 
