256 Remarks on M. Baruel's Process 



liquid is to be evaporated to dryness, at a gentle heat. The 

 residuum is to be then treated with alcohol very highly recti- 

 fied, which takes up the excess of sal ammoniac, and occa- 

 sionally a little muriate of iron ; because the alloy sometimes 

 contains a little of this metal. When the alcohol is no longer 

 coloured, the ammonio-muriate of iridium remains pure. It is 

 necessary merely to calcine it strongly in a crucible to have 

 pure iridium. This metal, being more infusible than rhodium, 

 can be melted only in very small quantities by the oxygen on 

 charcoal, or hydrogen blow-pipe. 



Remarks by the Translator. 



The preceding process was obligingly drawn up by M. 

 Baruel, at the request of a chemical gentleman from this coun- 

 try, who wished to know the actual method now practised at 

 Paris, for preparing the great masses of platinum of which 

 Coturiere forms his beautiful alembics. Permission was given 

 to publish the process in a work on practical chemistry, now 

 in preparation ; but as the period of its appearance is a little 

 uncertain, it has been thought fit to give it to the world in the 

 present form. Though it be fundamentally the same with that 

 published by M. Vauquelin in 1813, in the 88th volume of the 

 Annales de Chimie ; yet it is much superior in the clearness, 

 method, and definiteness of the operations. These indeed are 

 so explicit, that one of the most delicate processes of chemistry, 

 is thus brought within the compass of almost every operative 

 chemist. The paragraphs are here numbered, for reference in 

 annotation. 



The preliminary observations in § 2, are very useful ; they are 

 not given by M. Vauquelin. M. Baruel is judicious in pre- 

 scribing, with M. Laugier, a retort and receiver for conducting 

 the aqua-regia solutions. In all cases where nitric or nitro- 

 muriatic acid is concerned, a great waste and annoyance are 

 occasioned by the escape of acid vapours. These may be ef- 

 fectually saved, by connecting, with a somewhat long and wide 

 tube, the first balloon to a second containing a very little water. 

 The first balloon should have three apertures ; one connected 



