DALTON. 63 



ing a proof, were it required, that a single human intellect, 

 even when brightest and clearest, is a weak and limited thing. 

 As Dalton grew older, he overrated his powers. A paper of 

 his, sent to the Koyal Society, and rejected, first aroused in 

 him the suspicion of this fact. On the returned paper Dalton 

 wrote a few words, which have the force of an epitaph : * I 

 sent the account of the Phosphates and Arseniates to the 

 Eoyal Society. It was rejected. Cavendish, Davy, Wollas- 

 ton, and Gilbert, are no more !' 



On the 18th of April 1837 he was seized with an attack 

 of paralysis, from which he never quite recovered. On Feb- 

 ruary 15th, 1838, he was attacked again; but rallying, he 

 still talked of science ; and speaking of a scientific man whom 

 he had seen in France, he said, 6 Ah ! he was a wreck then, 

 as I am now.' His end was near. On May 27th, attempting 

 to rise from bed, he fell on the floor and died. 



It would be injudicious to close this sketch without ad- 

 verting to some modifications of opinion the atomic theory 

 has undergone and is still undergoing. Just at this time 

 chemists are divided in opinion as to the existence or non- 

 existence of atoms ; and for some years past a distinction has 

 been found necessary between molecules and atoms. The ex- 

 pression equi-valent has no longer the universality claimed for 

 it by Dalton. Chemists now speak of mono- di- tri-valents, 

 &c. 



The atomicity or non-atomicity of matter will probably 

 never be determined ; but the definite proportionality of che- 

 mical combination, as established by Dalton, is a fact. As- 

 sume the existence of atoms, and we find a cause for this 

 definite proportionality ; deny the existence of atoms, and the 

 result is inexplicable. To quote an expression of Monsieur 

 Dumas : Matter may be atomic, or it may not be atomic ; but 

 if atomic, its elements must observe definite ratios of combination 

 exactly as they do now. 



