ARTICLE XXVI, 



On the Decomposition of the Alkaline Sulphates by Hydrochloric Acid and Chlorine. 

 By R. A. Tilghman. Raid June 18, 1852. 



From the fact of the decomposition of the sulphates of baryta, Btrontia, and lime, by the 

 contact of a current of vapour of water at a high temperature, we are naturally led to in- 

 vestigate the action of other bodies of similar constitution under the same circumstances. 

 Substituting chlorine for oxygen in its combination with hydrogen, we have hydrochloric 

 acid gas in the place of water; and it will be remembered that chlorine in some ca-> - 

 exhibits more powerful electro-negative energies than oxygen; thus, the chloride of 

 hydrogen is a strong acid, while the oxide is a neutral substance, and the chlorides of the 

 alkaline metals are neutral, while their oxides are strong alkalies. 



It would seem probable, therefore, that the action of hydrochloric acid gas upon the 

 sulphates above named, should be more powerful than that of vapour of water. 



A current of hydrochloric acid gas was dried by passing through pumice drenched with 

 sulphuric acid, and then conducted by a platinum tube into the bottom of a deep and nar- 

 row platinum crucible, which was filled with small pieces of sulphate of baryta, and the 

 v\h>>lc heated to high redness by a gas (lame urged by a strong jet of air. 



After half an hour's heat, the contents of the crucible were boiled in water, giving a 

 solution neutral to test paper, which was found to consist "f chloride of barium. \n 

 analysis of the portion nearesl to the influx of the gas, showed that twenty -seven per cent. 

 of the sulphate of baryta had been converted into chloride of barium; a decomposition 

 considerabIy>greater, judging from former experiments, than would have been effected by 

 vapour of water in the same time, and at the same heat. Tin- experiment was r< j" at< d 

 1>\ passing the dry hydrochloric acid gas over the sulphate of baryta, heated in a porce- 

 lain tube; the escaping gases were passed through water in a Woulfe's bottle, and iIm' 

 incondensable portion collected in a gas bell. The water in the Woulfe's bottle was found 

 to contain, besides the excess of hydrochloric acid, a considerable quantit) of sulphur 

 acid, and a trace of sulphuric acid. The incondensable gas proved to be oxygen. About 

 one-half of the sulphate of baryta had been converted mi" chloride of barium, 'lie fusing 

 of which, by preventing the free contact of the hydrochloric acid gas with the undecom- 

 posed sulphate, causes the action to become slower and slower. 

 vol. \. — 63 



