According to (among others) Wikipedia and Oliver Sacks (Uncle Tungsten, 2001), Thomson was an early adopter of Daltons atomic theory, presenting it much more clearly than Dalton himself.
I have not been able to find any trace of this in the 1810 edition of the «Elements»; perhaps «A System of Chemistry of Inorganic Bodies., 1831» is more to the point. (In the chapter on Affinity, beginning on p. 478, Thomson speaks of „particles of bodies“, forming other, „integrant“, particles consisting of different kinds. He never mentions anything about their beeing of equal size etc. Except for frequently quoting Dalton for experiments, on p. 482 he is quoted as assigning different sizes to particles of different gases. On p. 479 the difference between homogeneous affinity - cohesion and heterogeneous affinity - causing chemical bonds is introduced.)
The «Elements» have been digitized by Google. The OCR, however, worked rather badly in most parts. The pdf file with the scans can be found here (53.2 MB, so download only if you need to).
For an appraisal of the OCR quality see the following part from p. 457:
google version:
4. The bne of the common heni of the turkey), and the
dwk, has a good deal of resemblance to that of quadrupeds.
But it ffiSers in the Mlowing parlicutars: 1. It contains a
IMmsiderable quantity of albumem; The piciomof has no
sensinle sweet taste. but is very acrid and biltev | 3. it coi,i
laias very little soda; 4 The rtsia is not pieetpiMed by
couiuiuu superacetate of lead; but superacetate, boiled with
Qa╟4oustk of its w,i,ht of Utbargte, oocanws it t╟ psosipit-
tate.
emendated version:
4. The bile of the common hen, of the turkey, and the
duck, has a good deal of resemblance to that of quadrupeds.
But it differs in the following particulars: 1. It contains a
considerable quantity of albumem; 2. The picromel has no
sensible sweet taste, but is very acrid and bitter; 3. It con-
tains very little soda; 4 The resin is not precipitated by
common superacetate of lead; but superacetate, boiled with
one-fourth of its weight of litharge, occasions it to precipi-
tate.
I emendated the text manually. The corrected text is to be found here. Italics were marked by <i> and </i> The little ring,
denmoting degrees, is coded as ˚.
(Google_s original OCR text can be downloaded from the same site as the pdf.)
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