448 Royal Society. 



to the decomposition of atmospheric air during putrefactive processes 

 going on at the bottom of the sea. Dr. Daubeny offers objections to 

 the theory of that gas rising to the surface in consequence of the high 

 temperature to which it has been subjected. He conceives that the 

 air which Dr. Davy examined cannot have been derived from sea- 

 water, but must have originated from the atmosphere itself, with 

 which the volcano communicated. The author is disposed to attach 

 great importance to the accurate examination of the gases given out 

 by warm springs, and recommends the prosecution of the inquiry. 



* A paper was also read, entitled, " Experimental Researches on 

 Atomic Weights." By Ed ward Turner, M.D., F.R.S. Lond. and Edinb., 

 Professor of Chemistry in the University of London. 



This paper is a continuation of the Essay, by the same author, on 

 the Composition of the Chloride of Barium, which was published in 

 the Philosophical Transactions for 1829*. Having shown that the 

 atomic weights current among British chemists, though in some in- 

 stances correct, or tolerably approximative, have, as a whole, been 

 adopted on insufficient evidence, he proceeds, in this paper, to give 

 an account of the experiments he has made to ascertain the equivalent 

 numbers for lead, chlorine, silver, barium, and nitrogen. Finding, with 

 reference to lead, that the method adopted by Berzelius did not afford 

 uniform results, he endeavoured to ascertain the quantity of subsul- 

 phate of lead which given weights of metallic lead and the protoxide 

 of that metal respectively produce. He details the mode he employed 

 for the conversion of metallic lead into the subsulphate by a mixture 

 of nitric and sulphuric acids, diluted with an equal bulk of water, and 

 the precautions he adopted to avoid loss. The mean of three expe- 

 riments gave 146*375 grains of sulphate of lead for 100 grains of 

 metallic lead. By the mean of four experiments, Berzelius had ob- 

 tained, instead of the former number, 146*419. Dr. Turner adopts 

 the mean of the whole, namely, 146-41. By prosecuting this inquiry, 

 he finds the sulphate to consist of 73*575 of protoxide of lead, and 

 26*425 of sulphuric acid; and that the former contains 5-274 of 

 oxygen. According to these results, the equivalent number for lead 

 is 103-6. 



By experiments with the chloride of lead, which gave very uniform 

 results, Dr. Turner obtained an equivalent number for chlorine, closely 

 agreeing with that calculated from the analysis of chlorate of potash 

 in the experiments of Berzelius, namely, 35*45, but totally incon- 

 sistent with the atomic weight assigned to it by British chemists. The 

 accuracy of this result was further confirmed by a careful comparative 

 analysis of the binoxide and bichloride of mercury. 



The author next endeavoured to determine the equivalent number 

 for silver, by the analysis of its oxide and sulphuret, but could not 

 arrive at any precision in his results. The equivalent number for 

 barium may be calculated from his analysis of the chloride already 

 published in the paper before alluded to. His investigation of the 

 equivalent of nitrogen was attempted by means of the analysis of the 

 nitrates of silver, of lead, and of baryta ; the mean result of which 



* See Phil. Mag. and Annals, N.S. vol. viii. p. 180; and Lond. and 

 Edinb. Phil. Mag., vol. i. p. 109. 



