Intelligence and Miscellaneous Articles. 557 



mium, is thrown down. This, after edulcoration, is heated in a retort 

 with a sufficient quantity of nitric acid until the acid has passed over, 

 and the osmium removed as osmic acid. The residue in the retort 

 is removed, ignited with nitre and caustic potash which is free from 

 silica, in a silver crucible, for an hour, and the ignited mass softened 

 and dissolved in cold distilled water. The solution is left to clear 

 for 2 hours in a corked flask, the perfectly transparent, beautiful 

 orange-coloured solution removed with a siphon from the insoluble 

 portion, and the alkaline liquid neutralized with nitric acid ; this 

 produces a precipitate of velvety-black sesquioxide of ruthenium, 

 which after edulcoration and drying is reduced in a current of hy- 

 drogen. In this way perfectly pure metallic ruthenium is obtained. 

 This mode of separating it from the other platinum metals, with the 

 exception of osmium, is based on the behaviour of the solution of 

 the sesquichloride of ruthenium, which is decomposed by heat into 

 free muriatic acid and sesquioxide. The oxide of osmium is mixed 

 with the oxide of ruthenium, as the solution contains chloride of 

 osmium, which is likewise decomposed. The osmium-iridium is 

 only partially decomposed in the above treatment with chlorine, and 

 must therefore be treated with it three or four times. 



Ruthenium thus prepared forms angular pieces, of metallic lustre, 

 which are porous, and very closely resemble iridium. Its specific 

 gravity is very low, viz. 8*6 at 61° F. ; but it is highly probable that 

 it is but little inferior in this respect to iridium, for some porous 

 iridium, which was prepared in a similar manner from the blue oxide 

 of iridium IrO 2 , had a specific gravity of 9*3. Ruthenium is very 

 brittle, does not fuse in the flame of the oxyhydrogen blowpipe, and 

 is almost insoluble in acids ; aqua regia dissolves mere traces of it. 

 After osmium, ruthenium has the greatest affinity for oxygen of all 

 the platinum metals, for it is very readily oxidized on heating to 

 redness. There are four oxides of ruthenium: — 



I. The protoxide, RuO, is obtained when 1 equiv. Ru CI 2 is heated 

 strongly with rather more than 1 equiv. NaO CO 2 in a current of 

 carbonic acid, and then extracted with water. The protoxide is left 

 as a blackish-gray metallic powder, which is insoluble in acids, and 

 is reduced by hydrogen at the ordinary temperature. It is anhy- 

 drous, and contains in 100 parts 86*6 ruthenium and 13*4 oxygen. 

 The hydrate is still unknown, and will probably be as difficult to 

 prepare as the hydrate of the protoxide of iron. 



II. Sesquioxide, Ru 2 3 . Anhydrous. — When the pulverulent 

 metal is exposed to a bright red heat in a platinum crucible over 

 Piclet's glass-blower's lamp, it acquires a black colour, and very 

 quickly absorbs for every 100 parts 18 parts oxygen ; subsequently 

 the oxidation slowly proceeds further until the oxide becomes 

 blackish blue, and then contains 23-24 parts oxygen to 100 of 

 ruthenium. This oxide increases still more in weight when exposed 

 to a very long-continued red heat, but it could not be oxidized to 

 RuO 2 . 



The hydrate, Ru 2 O 3 -j- 3aq, is obtained by precipitating the ses- 

 quichloride with alkalies. It must be well-washed, and nevertheless 



