164 lieu lews. 



tion of Gases, and the Composition of Chemical Compounds, which 

 afterwards made him so famous. 



The first of his scientific publications, " Meteorological Obser- 

 vations and Essays," appeared in 1793, soon after his removal 

 to Manchester, to enter on the office of Tutor in Mathematics and 

 Natural Philosophy in a Dissenting College in that town. He 

 resigned this appointment at the end of six years, but continued 

 to reside in Manchester to the close of his days. It is not our 

 intention here to trace the events of his personal history : it will 

 suffice, therefore, to state that the reputation he acquired by his 

 Meteorological Essays, was greatly increased by the publication in 

 the Manchester Philosophical Memoirs, from 1799 onwards to 

 1801, of Essays on Evaporation; on the conduction of heat by 

 liquids ; on the constitution of mixed gases ; on the force of steam 

 or vapour from water, and other liquids ; on evaporation ; and on 

 the expansion of gases by heat. 



These remarkable papers attracted the notice of the scientific 

 world and led to Dalton's invitation to lecture at the Royal Insti- 

 tution, London, in 1804, where Davy was then delighting audi- 

 tors of all ranks and professions by his chemical prelections. In 

 the short course of lectures Dalton delivered at this time, he an- 

 nounced the results of researches, which were not published till 

 1805. These embraced an experimental enquiry into the elastic 

 fluids of the atmosphere; an investigation into the diffusion of 

 gases ; and a Memoir on the absorption of gases by water. It 

 was this last paper, read to the Manchester Society in 1803, but 

 not published till 1805, which contained what its author called a 

 " Table of the relative weights of the ultimate particles of gaseous 

 and other bodies ;" or what we should now name a Table of Atomic 

 Weights. It was the first such Table, and was destined more 

 than any of his publications to make its author memorable. 



He was led to construct such a Table originally from the de- 

 sire to solve a problem important to meteorology : " why is one 

 gas more soluble in water than another ?" He thought the dif- 

 ferent solubilities of gases might prove to depend on the unlike 

 size of those ultimate particles, which he afterwards named atoms, 

 and regarded as so essentially indivisible that he enforced on his 

 pupil, Mr Hansome, that a law of Multiple Proportion could not 

 fail to exist, in these naive, but most expressive words — " Thou 

 knows it must be so, for no man can split an atom!" (Life, 

 p. 222.) 



From this time forward, chemistry much more largely occupied 

 his time than before, and fully alive to the novelty and import- 

 ance of his views on atomics, he proceeded to embody them in a 

 work which his modesty and simplicity of character did not pre- 

 vent him from naming a " New System of Chemical Philosophy ,•" 

 a title which the scientific world cordially and admiringly received 



