TWO NEW METALS IN CRUDE PLATINA^ 221 



fummer, and had been communicated to Sir Jofeph Banks, after 

 which an account of one of thefe metals appeared in France, 

 by M. Defcolil *, and alfo by M. Vauquelin. The properties 

 afcribed to it by the French chemifts are, 1. That it reddens 

 the precipitates of platina made by fal ammoniac ; 2. That it 

 difTolves in marine acid; 3. That it is precipitated by galls 

 and pruffiate of potafli. The properties mentioned by Mr. 

 Tennant are, that it diffolves in all the acids, but leaft m marine 

 acid, with which it forms odtahedral cryftals. The folution 

 with much oxigen is deep red, witii a fmaller proportion green 

 or deep blue. It is partially precipitated by the three alkalies 

 when pure. All the metals, excepting gold and platina, pre- 

 cipitate it. Galls and precipitate of potaQi take away the colour 

 of this folution, but without any precipitate, and afford an 

 eafy teft of its prefence. The oxide therefore lofes its oxigen, 

 by water alone. When combined with gold or Jilver, it can- 

 iiot he Jeparated by the ufual procefs of rejining thefe metals. As 

 the French chemifts have not given a name to the metal, Mr. 

 Tennant inclines to call it Iridium, from the various colours of it 

 in folution. 



The fecond new metal is obtained by heating the black pow- New metal 

 der with pure alkali in a filver crucible. The oxide of this metal ^r"'"^* 

 unites with the alkali, and may be expelled by an acid and ob- 

 tained by diftillation, being very volatile. The oxide has a very 

 ftrong fmell, from which Mr. Tennant has called it Ofmiiun. 

 It does not redden vegetable blues, but ftains the fl<in of a deep 

 red or black. The oxide in folution with water has no colour, 

 but by combining with akalli or lime becomes yellow. With 

 galls it gives a very vivid blue colour. All the metals, ex- 

 cepting gold and platina, precipitate this metal. If mercury is 

 agitated with the aqueous folution of the oxide, an amalgum 

 is formed, which, by heat, lofes the mercury, and leaves the 

 ofmium pure as a black powder. 



* See our Journal, Vol. VIII. p. 118. 



SCIENTIFIC 



