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 baryta 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 1 1 8 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.' 
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, remained 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 w r as 
