Obtaining Iridium and Osmium from the Platinum residue. 371 
The rotating armature, has excited a great deal of curiosity here. 
The -mechanics were very much puzzled by it and supposed it went 
by steam. I took care to conceal the battery which excited it and 
conveyed the galvanic fluid along two slender wires, without attract- 
ing their attention. 
I send you the above little instrument, the peculiarity of it is, that 
it makes its own magnet while revolving. r 
Art. XIII.—A Method of obtaining Iridium and Osmium from the 
Platinum residue; by F. Wouter. Translated by J. C. Booth, 
received in a letter to the editor, dated Berlin, April 20th, 1834. 
Tue black powdery residue, which remains upon treating the 
platinum-sand with nitro-muriatic acid, contains, as is well known, 
a certain quantity of a natural alloy, osmium-iridium and probably no 
inconsiderable proportion of uncombined iridium in powder. It has 
always been a difficult matter to separate the two last metals from 
the ore, as well in consequence of the difficult decomposition of the 
alloy, as on account of the presence of large quantities of foreign 
ingredients, and particularly of titanate of iron. The discovery of 
a simple and unexpensive method of decomposition was so much the 
more desirable, since this remainder lias accumulated in places where 
platinum is largely worked, and it is not improbable that an easy 
method of obtaining iridium, a metal nearly allied to platinum, may 
lead to a highly useful mode of application in the arts. It was for 
this purpose necessary to find the means of extracting osmium and 
iridium alone without affecting the titanate of iron; for since the par- 
ticles of the latter cannot be separated by the magnet or otherwise 
mechanically, the presence of such large quantities of iron and tita- 
nic acid might render the employment of such a method difficult. 
The method I am about to describe appears to me sufficiently adap- 
ted to the purpose, and could be employed in the large way without 
difficulty. It is founded on the means resorted to by Berzelius of 
bringing iridium, insoluble im aqua-regia, to a soluble state and one 
suited for the preparation of its other combinations,—viz. by passing 
chlorine over a heated mixture of iridium and chloride of sodium. 
The process for the platinum-residue* is as follows :— 
* Tt is unnecessary to powder if. The trouble of mineralogists, will however be 
amply repaid, by previously spreading it out upon paper and seeking out the larger 
Vou. XXVI.—WNo. 2. 48 
