DR. TURNER ON CHLORIDE OF BARIUM. 



293 



of barium is therefore 106 ; and on mixing this quantity of the chloride with 

 88 parts of sulphate of potash, each being previously dissolved in separate 

 portions of distilled water, he finds that the clear liquid left after the insoluble 

 sulphate of baryta has completely subsided, is not rendered turbid either by 

 muriate of bai-yta or sulphate of soda. It is hence inferred, that by double 

 decomposition the whole of the baryta has united with all the sulphuric acid, 

 and that all the potash and muriatic acid are contained in solution in the 

 form of muriate of potash. The resulting sulphate of baryta, after being col- 

 lected and heated to redness, weighed exactly 118 parts ; while the muriate of 

 potash, when collected and duly heated, yielded 76 parts of chloride of 

 potassium. It follows from this experiment that 40 is the equivalent of sul- 

 phuric acid, and 48 of potash ; and on mixing with one equivalent of chloride 

 of barium such a quantity of any soluble sulphate as should produce a similar 

 interchange of elements, the constitution of that salt would be exactly de- 

 termined. ,^ gjd^ ,j,,f(f.,. 

 This leading experiment, from which Dr. Thomson deduces the composition 

 of chloride of barium as well as the atomic weight of baryta, is maintained 

 by Berzelius to be inexact. He prepared chloride of barium and sulphate of 

 potash with the greatest possible care ; and on mixing them in the proportion 

 mentioned by Dr. Thomson, he found that a considerable quantity of the former, 

 about 2.25 per cent of the amount employed, i-emained free in the residual 

 liquid. (Lehrbuch der Chemie, vol. iii. p. 106.) In an answer to this objection, 

 published in the Philosophical Magazine and Annals of Philosophy for last 

 March, Dr. Thomson has maintained the accuracy of his original experiment, 

 stating that it had recently been repeated by six of his practical pupils, and in 

 no case did the residual liquid contain a trace either of sulphuric acid or 

 baryta. I regret that my observations have forced me to a conclusion pre- 

 cisely opposite. I have made the experiment in question repeatedly, with the 

 greatest care, and with perfectly pure materials, and in every instance the re- 

 sult coincided with that obtained by Berzelius. The sulphate of potash which 

 I used was prepared by repeated crystallization from the crystals of that salt 

 as sold by the druggists, and was so pure that I could not detect in it a trace 

 of foreign matter. The chloride of barium was formed by the action of pure 

 muriatic acid on native carbonate of baryta. The resulting solution was 



