TRANSACTIONS OF SECTION B. 631 



the theory put forward two years ago in the two cases of the hydrocarbons and 

 the sulphur compounds of coal-gas ; the cause of the deposition of ' gas-carbon ' is 

 explained, and the operations of the same physical principles is believed to have 

 been the origin (for the most part) of the grapliite which abounds (in places) in 

 the (archsean) primitive crystalline rocks. Reference is made to the presence of 

 hydrocarbons in heads of comets and of carbon in meteorites. 



8. On Closed-chain Formidce. By J. E. Maesh, B.A. 



9. On Van't Hoff's Hypothesis and the Constitution of Benzene. 

 By J. E. Marsh, B.A.^ 



FRIDAY, SEPTEMBER 7. 

 The following Papers were read : — 



1. Discussion on the Chemical Prohlems presented hy Living Bodies, opened 

 by Professor Michael Foster, Sec.B.S. 



2. On the Atomic Weight of Oxygen. 

 By Alexandee Scott, M.A., D.Sc.,'F.B.S.E. 



After giving a brief historical sketch of the work which had been done to de- 

 termine with the greatest possible accuracy the atomic weight of o.xygen — that of 

 hydrogen being taken as the unit — the author pointed out amongst other sources of 

 error that the presence of air to the e.xteut of only ^-j^^- of the volume of hydrogen 

 used would be sufficient to raise the value lo-9G deduced from Dumas' experiments 

 to 16-00. Similarly with regard to Regnault's ratio of the densities originally given 

 as 15-96 also, but shown by applying the correction proved necessary by Lord 

 Rayleigh when recalculated by Crafts to be only lo-Ql, the presence of jj^j-j; of air 

 by volume in the hydrogen would be alone sufficient to account for this* being so 

 far below 16, to say nothing of the traces of water vapour and sulphur dioxide 

 also most probably present. 



The recent work of Professor J. P. Cooke and Mr. Richards, as well as the re- 

 determination of the ratio of the densities of the gases by Lord Rayleigh, have 

 tended to remove the value for the atomic weight of oxygen further from 16 

 instead of raising it, the corrected number of Professor Cooke being 15 869. Lord 

 Rayleigh's ratio of the densities being 15-884, and if we take 1-998 : 1 as the ratio 

 of the volumes in which hydrogen and oxygen combine to form water, we get from 

 it 15-90 as the atomic weight of oxygen. 



The author then described his latest experiments on the ratio of the combining 

 volumes of hydrogen and oxygen and pointed out that the volume of hydrogen 

 required seemed to decrease when it was continuously evolved from the same 

 vessel, four consecutive experiments with hydrogen from the electrolysis of dilute 

 hydrochloric acid with zinc amalgam giving 



' Published in extenso in PMl. Mag. November 1888. 



