Ordinary Meeting, November 17tb, 1874. 
Edward Schfnck, Pli.D., F.KS., &c., President, in the 
Chair. 
'^Some Remarks on Daltons First Table of Atomic 
Weights,” by Professor Henry E. Roscoe, F.R.S. 
As the Society is aware, the first table, containing the 
relative weights of the ultimate particles of gaseous and 
other bodies, was published as the 8th and last paragraph to 
a paper by Dalton, “ On the Absorption of Gases by Water 
and other Liquids,” read before this Society on October 21, 
1803, but not printed until the year 1805. There appears 
reason to believe these numbers were obtained by Dalton 
after the date at which the paper was read, and that the 
paragraph in question was inserted at the time the paper 
was printed. The remarkable words with which he intro- 
duces this great principle give us but little clue to the 
methods which he employed for the determination of these 
first chemical constants, whilst in no subsequent publication, 
as in none of the papers which have come to light since his 
death, do we find any detailed explanation of how these 
actual numbers were arrived at. He says, “ I am nearly 
persuaded that the circumstance ” (viz. that of the different 
solubilities of gases in water) “ depends upon the weight 
and number of the ultimate particles of the several gases — 
those whose particles are lightest and single being less 
absorbable, and the others more, according as they increase 
in weight and complexity. An inquiry into the relative 
weights of the ultimate particles of bodies is a subject, so 
far as I know, entirely new. I have been lately prose- 
cuting this enquiry with remarkable success. The principle 
cannot be entered upon in this paper ; but I shall just sub- 
join the results, as far as they appear to be ascertained by 
my experiments.” 
* Manch. Mem., YoL I., 2nd Series, p. 28(j, 
