A MATERIAL AGENT. 7 



6. That it operates in a sensible manner on 

 the nervous system, producing intense pain, and 

 disorganization of the tissues when in excess.* 



But if caloric were a mere property or quality, 

 how could it be taken from one body and added 

 to another? Or if it augment the volume of 

 other bodies, must it not itself have volume, 

 occupy space, and therefore be a material agent? 

 Would it not be mere jargon to speak of the 

 radiation, reflexion, convection, and conduction 

 of a mere quality, or immaterial property ? And 

 if caloric were only the effect of vibratory motion 

 among the particles of ponderable matter, how 

 could it radiate from hot bodies without the 

 simultaneous transition of the vibrating parti- 

 cles? But it is certain that when iron, copper, 

 and other metals are heated to any temperature 

 below the point of ignition; like boiling water, 

 they give off caloric freely, without any sensible 

 loss of ponderable matter. 



* The same reasoning on which is founded all belief in the 

 material existence of the outward universe applies equally to 

 caloric. No metaphysical sophistry can refute the belief of man- 

 kind, that whatever operates in a sensible manner upon material 

 organs, must be a material substance; for the obvious reason, 

 that " there can be no virtue without substance," as maintained 

 by Newton. It was an axiom among the ancients, that nothing 

 can be said to exist, unless it can be recognized by the senses. 

 " Nihil esse potest, nisi quod attigimus, aut vidimus." And 

 it was observed by an able writer in the Church of England 

 Review, that our words thing, and think, were derived from the 

 Greek verb Qiyy-tv, to touch; that is, a thing is what we first 



