Intelligence and Miscellaneous Articles. 393 



1 1 grains of sulphate of potash, both in solution ; and it was found 

 that after the sulphate of barytes had precipitated, the residual 

 liquid contained no sensible quantity of sulphuric acid or of barytes. 

 Berzelius in the third volume of his Larbok i Kemien, stated that 

 when these proportions were used, there always remained an excess 

 of barytes. 1 requested several of my practical pupils to repeat the 

 experiment without mentioning my object, and they all gave me the 

 same proportions of the two salts that I had previously stated. I was 

 induced in April 1828 to try the experiment anew, and for this pur- 

 pose prepared a quantity of pure cliloride of barium and of sulphate 

 of potash. After repeating the experiment about thirty times, varied 

 in every possible way, I found myself quite unable to determine the 

 exact proportions of the two salts which decompose each other. 

 There was no difficulty in finding the proportions which, when mixed 

 together, leave no sensible residue of sulphuric acid and barytes in 

 solution. But when I attempted to collect the sulphate of barytes 

 and chloride of potassium, 1 never found the quantities to agree in 

 any two consecutive experiments. Suspecting that the method of 

 using double filters might be the cause of the uncertainty, I substi- 

 tuted single filters of Indian paper, which were finally burnt in pla- 

 tinum crucibles. I was therefore obliged to give up the attempt of 

 determining the atomic weight of barytes by this method. Dr. Turner 

 has since explained the cause of this failure, which indeed I suspected 

 at the time. It is owing to a portion of the sulphate of potash adhe- 

 ring obstinately to the sulphate of barytes, and thus escaping decom- 

 position *. Foiled in this, 1 substituted sulphate of ammonia, and 

 afterwards sulphuric acid. By mixing a solution, containing a given 

 weight of chloride of barium with an excess of sulphate of ammonia 

 or of sulphuric acid, evaporating to dryness, and then exposing the 

 residual salt to a strong red heat, I succeeded in determining the 

 weight of sulphate of barytes, which is the equivalent for a given 

 weight of chloride of barium. The same weight of chloride of barium 

 was afterwards decomposed by nitrate of silver, and the weight of 

 chlorine determined from my old data that chloride of silver is a 

 compound of 



Silver 1375 



Chlorine 4'5 



18-25 



The result of these trials (which occupied me for several weeks) was, 

 that sulphate of barytes is a compound of 



Sulphuric acid 5 



Barytes 95006 



Now as 5 is the atomic weight of sulphuric acid, it is clear that 95 

 must be the atomic weight of barytes." — System of Chemistry, (In' 

 organic Bodies,) IS.'Jl. vol. i. p. 420. 



Dr. Thomson observes that these experiments are confirmed by 



• Phil. Mag. and Annuls, N.S., vol. viii. p. 183. 

 N. S. Vol. 10. No. 59. Nov. 1831. 3D those 



