Dr. Turner on the Composition of Chloride of Barium. 185 



The process by which I have endeavoured to analyse 

 chloride of barium consists of two parts. In the first, a given 

 quantity of the chloride was dissolved in water, and the baryta 

 thrown down as sulphate by sulphuric acid. In the second, a 

 similar solution was precipitated by nitrate of silver, and the 

 chlorine inferred from the quantity of fused hornsilver which 

 was produced. The quantity of chloride of barium employed 

 in each experiment varied from 30 to 40 or 45 grains. The 

 sulphuric acid had of course been purified by distillation, and 

 left no residue when evaporated on platinum. 



The process by sulphuric acid was varied : one while the 

 solution and precipitate were evaporated to dryness in a plati- 

 num capsule; and at another, the insoluble sulphate was 

 collected on a double filter. Both methods were frequently 

 repeated, and the sulphate of baryta was always dried by ex- 

 posure to a red heat. The quantity of sulphate of baryta ob- 

 tained by the first method from 100 parts of the chloride ranged 

 from 112*17 to 112*2, being more frequently the latter than 

 the former; and 112*19 may be adopted as a mean of the most 

 successful experiments. The quantity obtained by filtration 

 fell rather short of this, varying in the best experiments from 

 112*08 to 112*12. The difference is referable to a trace of 

 sulphate of baryta being retained by the acid solution, in which 

 it may really be detected by evaporation. The first series of 

 experiments may therefore be considered the more accurate, 

 and it may be inferred that 100 parts of pure chloride of 

 barium are capable of yielding 112*19 parts of sulphate of 

 baryta. This result agrees very closely with that stated by 

 Berzelius in the last edition of his System of Chemistry, who 

 in one experiment got 112*17, and in another 112*18, of sul- 

 phate from 100 parts of chloride of barium. According to 

 Dr. Thomson, 100 parts of the chloride yield only 111*32 

 parts of sulphate of baryta. It is proper to state, in reference 

 to the foregoing experiments, that traces of chloride of barium 

 are apt to adhere to the sulphate of baryta ; but this source 

 of error is easily avoided by decanting the supernatant fluid 

 after subsidence, and stirring the precipitate with hot water 

 acidulated with sulphuric acid. 



In order to determine the chlorine of chloride of barium by 

 means of silver, it was desirable to ascertain the composition 

 of hornsilver. For this purpose some fine silver contain- 

 ing only traces of gold and copper was dissolved in nitric 

 acid, precipitated by sea-salt, digested in dilute nitro-muriatic 

 acid, and washed. The dry chloride was then reduced by 

 means of carbonate of potash in the usual manner, and after 

 throwing a few fragments of nitre upon the fused metal, it 

 was granulated and then boiled repeatedly in distilled water, 



N.S. Vol. 8. No. 45. Sept. 1830. ' " 2 B In 



