Intelligence and Miscellaneous Articles. 559 



Chlorides of Ruthenium. 



I. Protochloiide of Ruthenium, RuCl In my former experiments 



it appeared to me as if ruthenium were little acted upon by chlorine. 



1 subsequently observed however that after very long-continued 

 treatment the metal was converted at a faint red heat into proto- 

 chloride. When ruthenium is heated to redness in the bulb of a 

 reduction-tube over an Argand lamp, and dry chlorine passed over 

 it, yellow vapours (probably the highest and most volatile chloride) 

 are first disengaged and carried away by the current of gas ; the 

 metal seems not to change and to increase in bulk ; subsequently 

 some sesquichloride sublimes, and the metal becomes black ; after 



2 hours it is converted into a black partially crystalline protochlo- 

 ride. It is however not always possible to saturate the ruthenium 

 perfectly with chlorine in one operation ; it is best to reduce the proto- 

 chloride formed to a fine powder, and to treat it again with chlorine. 

 In this way a combination is always obtained, yielding on analysis 

 numbers corresponding to the above formula. Water removes a 

 trace of sesquichloride from it ; otherwise it is insoluble in it and in 

 acids ; a solution of caustic potash has little action upon it even 

 when evaporated with it to dryness, 



Soluble Protochloride. — When the solution of the sesquichloride 

 is treated for a long time with sulphuretted hydrogen, a black-brown 

 sulphuret is precipitated, and the liquid acquires the well-known 

 beautiful azure-blue colour. The sulphuretted hydrogen can be 

 removed from this fluid by a current of atmospheric air, and in this 

 way a solutiou of the blue protochloride with muriatic acid obtained. 

 I regard this blue combination as the protochloride, although I can- 

 not vouch for the correctness of this view ; for it is not possible to 

 prepare it in a solid form or as a crystalline double salt, as it is very 

 readily decomposed, and passes into the orange sesquichloride. 

 I therefore attempted to obtain an idea of the composition of this 

 compound by precipitating the solution of the blue protochloride by 

 alkalies ; but the oxide thus obtained possessed the composition of 

 sesquioxide Ru° O 3 . This negative result is no direct proof against 

 my view, for I have observed that, in the decomposition of the lower 

 chlorides of iridium by alkalies, the higher oxide IrO is constantly 

 formed. Ruthenium must behave similarly, as it exhibits a greater 

 affinity for oxygen than that metal. The reasons which have led 

 me to regard the blue compounds as the protochloride are, — 1st, 

 HS, in its action upon the perchlorides of the other platinum metals, 

 converts them into lower chlorides ; 2nd, the sulphuret which sepa- 

 rates on the formation of the blue compound does not contain, as it 

 should, 3 atoms of sulphur to 2 of metal, but 2 and more atoms of 

 sulphur to 1 atom of metal ; 3rd, other reducing agents, as zinc, 

 percyanide of mercury, &c, colour the sesquichloride blue; 4th, on 

 heating the evaporated solution of the sesquichloride, it becomes 

 green (a mixture of blue and yellow protochloride), and at some 

 spots blue ; but it is not possible to prepare in this manner a pure 

 blue protochloride, because a portion of the salt is converted into a 

 basic compound. 



