558 Intelligence and Miscellaneous Articles. 



contains a few per cent, of the alkali. It forms a blackish-brown 

 powder, which dissolves with an orange colour in acids, glows sud- 

 denly when heated, and is not perfectly reduced at the ordinary tem- 

 perature by hydrogen. It is insoluble in alkalies. 



III. Oxide of Ruthenium, RuO 2 . Anhydrous. — On roasting and 

 igniting RuS-, a blackish-blue powder, with a greenish play of 

 colours, is obtained, which is insoluble in acids, and contains 307 

 parts oxygen to 100 of metal. It is obtained when RuO 2 , 2S0 3 is 

 exposed to a strong red heat in small grayish particles of metallic 

 lustre, and with a beautiful blue and green iridescence. 



The hydrate, RuO 2 + 2aq ?, has riot yet been analysed, but it will 

 undoubtedly possess the above composition; it is obtained as a 

 gelatinous yellowish-brown precipitate, when the solution of the 

 double chloride KC1 2 + RuCl 4 is mixed with NaO CO-, and evapo- 

 rated. It contains much alkali, dissolves with a yellow colour in 

 acids, and these solutions become of a rose-red on evaporation. 

 When heated in a platinum spoon it detonates with a lively incan- 

 descence, and is projected in all directions. In the dry state it has 

 the colour of impure oxide of rhodium. 



IV. Ruthenic acid, RuO 3 , is not yet known in its isolated state. 

 It is most probably a very unstable compound, which is readily de- 

 composed into oxide and oxygen. It occurs as basic rutheniate of 

 potash in the solution of the ruthenium which has been ignited with 

 potash and saltpetre. The composition of the acid was ascertained 

 in the same way as H. Rose analysed the ferrate of potash. For 

 the analysis however a rutheniate of potash was employed, which 

 had been prepared by igniting the metal with potash and chlorate 

 of potash. The salt could not be obtained crystallized, as the solu- 

 tion is readily decomposed. The solution is of a beautiful orange 

 colour, is very astringent to the taste, like tannic acid, and is neu- 

 tral, if too much potash and nitre has not been used in its prepara- 

 tion ; it colours organic substances black, owing to a deposition of 

 reduced oxide. Acids immediately precipitate from it a black oxide, 

 which contains potash if the solution had not been perfectly neu- 

 tralized with acid ; with a slight excess of acid however the precipi- 

 tated oxide contains some per cents, of .acid. When sulphuric acid 

 is used, a metal is obtained on reducing the oxide which contains 

 some sulphuret, and which it is very difficult to decompose at a 

 faint red heat in a current of hydrogen. I analysed the oxide con- 

 taining acid, especially that precipitated by nitric acid, and obtained 

 results which led me to believe that this oxide was RuO 2 + 2aq 

 (I was not then acquainted with the true hydrated oxide) ; but it is 

 very probable that, on igniting it in a current of carbonic acid in 

 order to determine the water, the sesquioxide is converted by the 

 action of the nitric acid into oxide. At present I consider this black 

 oxide to be a hydrate of the sesquioxide, because it dissolves in mu- 

 riatic acid, forming sesquichloride*. 



* Before I was acquainted with the true oxide and perchloride, I thought that 

 muriatic acid converted the hlack oxide with reduction into sesquichloride, espe- 

 cially as some chlorine was disengaged in the experiment. 



