PRESIDENTIAL ADDRESS, B.A. 1871. 165 



of the properties of atoms, carrying out the grand 

 conception of Lucretius, who "admits no subtle 

 " ethers, no variety of elements with fiery, or 

 " watery, or light, or heavy principles ; nor supposes 

 " light to be one thing, fire another, electricity a 

 " fluid, magnetism a vital principle, but treats all 

 " phenomena as mere properties or accidents of 

 " simple matter." This statement I take from an 

 admirable paper [by Fleeming Jenkin] on the 

 atomic theory of Lucretius, which appeared in 

 the North BritisJi Review for March 1868, con- 

 taining a most interesting and instructive sum- 

 mary of ancient and modern doctrine regarding 

 atoms. Allow me to read from that article 

 one other short passage finely describing the 

 present aspect of atomic theory : " The exist- 

 " cnce of the chemical atom, already quite a 

 " complex little world, seems very probable ; 

 " and the description of the Lucretian atom is 

 " wonderfully applicable to it. We are not wholly 

 " without hope that the real weight of each such 

 " atom may some day be known not merely the 

 " relative weight of the several atoms, but the 

 " number in a given volume of any material ; that 



