( 41 ) 



On the Chemical Composition of the Crystallized Oxy chloride of 

 Antimony. By James F. W. Johnston, A.M., F.R.S.E., 

 F.G. S., Reader in Chemistry and Mineralogy in the Univer- 

 sity of Durham. Communicated by the Author. 



It has been very long known, that when a solution of oxide 

 of antimony in muriatic acid is diluted with water, a white 

 powder is precipitated, which, after prolonged washing, still ob- 

 stinately retains a portion of the acid. This substance was for- 

 merly described under the name of the powder of algaroth. 



The difficulty of separating the whole of the acid from this 

 powder naturally leads to the opinion, that, when first precipi- 

 tated, it is itself a definite compound less easily decomposed than 

 the neutral chloride of antimony, or that it contains a quantity 

 of some such compound. In either case, as water continues to 

 separate acid from it at each effusion, it is obvious that washing 

 must decompose this compound. The newly precipitated un- 

 washed powder, therefore, must be, or must contain, the com- 

 pound in its normal state. 



We have many analyses of this substance, no two of which 

 agree, obviously because having washed it more or less, each 

 chemist operated upon a mixture in which the relative quanti- 

 ties of oxide and chloride of antimon}' actually differed. Ac- 

 cording to Bucholz, it contains 4f per cent, of dry muriatic acid; 

 according to Gronvelle it consists of 7 atoms oxide united to one 

 atom of chloride of antimony.* Dumas -f- gives as its compo- 

 sition 82 of chloride and 18 of oxide of antimony ; while Mr 

 Philips found it to contain 7.8 per cent, of muriatic acid, and 

 92.2 of oxide of antimony, or to consist of one atom of acid to 

 5^ of the base.| From results so discordant, it is impossible to 

 draw any conclusion in regard to the true nature of the com- 

 pound, or whether there be any constant and definite compound 

 of the chloride with the oxide of antimony. That oxides and 

 chlorides do unite there is now no doubt, but the difficulty of 

 obtaining these compounds in a crystalline form has hitherto pre- 



" Gmelin's Handbuch, I. p. 985. f 't'raite dc Chimie, iii. p. i'yj. 



X Tinner's Chemistrv, p. 697. 



