D ALTON 121 



ened it." It is an error to suppose that recent research 

 has removed Dalton's atomic theory or rendered it 

 obsolete. We now know that Dalton's atoms are not 

 atoms, but it is still true that " elements combine in con- 

 stant proportions by weight." In the words of Sir George 

 Darwin : " The vast edifice of modern chemistry has been 

 built with atomic bricks." From the later work of to-day 

 we know that the atom is not the ultimate form of matter. 

 There are corpuscles and ions inconceivably smaller ; but, 

 says Professor A. Smith ells, "few will deny that the 

 atomic theory stands to-day an indispensable instrument 

 for productive work ; it has neither had its day nor ceased 

 to be. We are now called upon to subdivide our atom, 

 to credit it with an unsuspected store of energy, to con- 

 sider it a congeries of unsubstantial electrons. There can 

 be no possible objection from our side ; it will undo nothing 

 that has been done, and we may have good hopes that it 

 will lead to the doing of many new things in chemistry." 



In 1802 Dalton ascertained the composition of the 

 atmosphere, namely, that a hundred volumes contain 

 twenty-one volumes of oxygen and seventy-nine volumes 

 of nitrogen. In 1804 he was asked to give a course of 

 lectures at the Royal Institution of London ; and in these 

 lectures he explained his views on the absorption of gases 

 by liquids, on the constitution of gases, etc. As a lecturer, 

 his manner lacked charm and gracefulness, but in spite of 

 these defects his genius was greatly appreciated. 



