ON THE ANTIMONY OXYCHLORIDES. 63 



agreeing determinations made with four different prepara- 

 tions. When heated in a retort nntil it boils, chlorine gas 

 is evolved, and, whilst pentachloride and trichloride of 

 antimony distil over, a residue of antimony pentoxide re- 

 mains in the retort. A modification of Rose's well-known 

 method of precipitation, first as insoluble antimoniate of 

 soda, and then as antimony sulphide, was employed for the 

 determination of the antimony. The precipitated sulphide 

 was (i) oxidized to Sb 2 4 , either by treatment with pure 

 fuming nitric acid, or by heating with from ten to twenty 

 times its weight of pure mercuric oxide ; and (2) the sul- 

 phide was completely reduced to metallic antimony by 

 heating gently in a current of hydrogen until sulphuretted 

 hydrogen ceased to be evolved. In the estimation of chlo- 

 rine, it was found that, when silver nitrate is added to a 

 solution of an antimony oxychloride acidified by nitric 

 acid, a small trace of antimony is invariably carried down 

 with the silver chloride. In order to free the precipitate 

 from antimony, the silver chloride is first heated gently in 

 a current of hydrogen, when the silver is reduced ; and on 

 stronger ignition, the whole of the antimony is volatilized 

 as the hydrogen compound. Thus 1*277 grm. of an 

 alloy, containing 2*5 parts of antimony to 97*5 parts of 

 silver, was found to lose on heating in hydrogen 0*0321 

 grm., corresponding to 97*48 per cent, of silver. 



The accuracy of each of the above methods was tested 

 by determining the percentage of antimony and chlorine 

 in pure antimony trichloride, the results agreeing closely 

 with each other and with the theoretical composition. The 

 objection to Schaeffer's method of decomposing the oxy- 

 chloride by boiling with a solution of sodium carbonate is, 

 that the precipitated oxide of antimony being in a very 

 finely divided state, a portion of it is apt to pass through 

 the filter on washing. 



The following are the results of analysis made with three 



