TRANSACTIONS OF THE SECTIONS. 587 



On the Chemical Composition of the crystallized Oxichloride of 

 Antimony. ByJ.F. W.Johnston, F.R.S.E. F.G.S., Reader 

 in Chemistry and Mineralogy in the University of Durham. 



When a solution of oxide of antimony in muriatic acid is 

 diluted with water, a white powder is precipitated, which has 

 been long known under the name of the powder of algaroth. 

 If the diluted solution be set aside, the precipitate assumes the 

 crystalline form, presenting the appearance either of a fine 

 sand with little lustre, of long transparent slightly yellowish 

 needles radiating from a centre, or of a congeries of micro- 

 scopic right oblique prisms having the acute terminal angle 

 about 84° 40'. These crystals are slightly yellowish, transpa- 

 rent, having occasionally a high degree of lustre^ give off no 

 water when heated, but at an elevated temperature decrepitate 

 and emit fumes of chloride of antimony. Heated with dry, or 

 boiled with a solution of, carbonate of soda, they are decom- 

 posed, and oxide of antimony remains. Nitric acid also decom- 

 poses them by the aid of heat, leaving antimonic acid. 



Several analyses of this substance have been published, but in 

 none of them, the author believes, was the compound employed in 

 a crystallized state ; and as it is partially decomposed by washing 

 with water, it is obvious, that unless in this state the true con- 

 stitution of the compound cannot be obtained by analysis. In 

 four experiments, crystals prepared at different times gave the 

 author 11-32, 11-26, 11-22, 11-215 per cent, of chlorine re- 

 spectively. Of these the highest is preferred, for the reason 

 above stated. In six experiments, by thi*ee different methods, 

 Mr. Johnston obtained: 1st, 76-82; 2nd, 75-93, 76-506, 75-98; 

 3rd, 76-6, per cent, of metallic antimony. Of these he prefers the 

 last. The compound, therefore, consists of 



Chlorine, 11*32= 2-55 atoms. 

 Antimony, 76-6 = 9-498 

 Loss, Oxygen, 12-08 = 12-08 



Atoms. 



or the (Cl + 0) : Sb : : 14-247 : 9-498 : : 3 : 2 nearly. It consists, 

 therefore, of oxide combined with chloride of antimony, and 

 they are in the proportion of one atom of chloride to 4| of oxide, 



orof2:9. This gives the formula 2 (3 CI + 2 SI) + 9 Sl The 

 results of calculation compared with experiment are as follow : 



Calculation. Experiment. 



36-29 



CI 6-63 11-49 11-32 



Use"} ^"-T^ 76-6 



O 6-75 11-79 12-08 



57-74 100- 100- 



