CHEMISTRY 83 



and shape of the electron have to be taken into account, and 

 when this is done the principle used in deducing the source of 

 the inertia has been acknowledged as quite unsound and must 

 in general lead to false results, as in the investigation as to 

 the question of the inertia of the electron. Therefore, we 

 may well hesitate to sweep away the last scrap of ordinary 

 matter from an electron until the proof rests on some prin- 

 ciple more convincing than that of the quasi-stationary state. 



Leaving the corpuscle, the negative electron, for the pres- 

 ent, let me ask you to consider what is meant by matter, by 

 substance. 



By substance I designate that of which things, objects, 

 are the visible, the perceptible evidences. Substance is that 

 which is external to ourselves and which is recognized by the 

 senses. That which possesses weight, more accurately mass, 

 and can be destroyed, not transformed but destroyed. I use 

 this last character, its destructibility, to distinguish it from 

 matter. A piece of wood is a definite quantity of the sub- 

 stance wood. In various ways the piece of wood, if left out 

 of doors, subjected to the atmospheric agencies, disappears, is 

 destroyed; if heated in the air to a sufficiently high tempera- 

 ture, it burns, it disappears, it is destroyed. In either case 

 there is no wood; a chemical change has taken place in which 

 the substance, wood, has been destroyed and something else, 

 some other substance or substances, has been produced with 

 absolute destruction of the substance wood; entirely new sub- 

 stances, ashes, gases, mold have been produced which did not 

 exist in but were, in part, formed by its destruction. 



To take an illustration — an imperfect conception of the 

 chemical change involved, let me say, in the destruction of a 

 piece of wood, or better of a crystal of sugar, may be obtained 

 by comparing the crystal of sugar to a regiment of soldiers in 

 review formation; the regiment is a unit composed of com- 

 panies, separate from each other; each company a unit com- 

 posed of officers and men. The unit companies would repre- 



