Dr. Hare's reply to Professor Olmsted. 1 3 



bodies themselves, which exert this influence on each other. 

 But if Dr. Hare is not thus to be understood, — if he do not mean 

 to assert such a doctrine, then why does he conceive it necessary 

 to suppose a fluid upon which the phenomena of repulsion de- 

 pend, — in which the self-repellent power resides, distinct from 

 the bodies themselves, which exhibit such repulsion IV 



I have said that the particles of ponderable matter obvi- 

 ously possess the power of mutual attraction ; they cannot 

 then be endowed at the same time with reciprocal repulsion. 

 But if they cannot be endowed with repulsion, why should 

 they be endowed with attraction ? says my antagonist. 



If I were to allege the whiteness of a thing as a reason 

 why it could not be black, would any person in his senses say, 

 but if it cannot be black, how can it be white ? Does the 

 presence of attraction prove the absence of attraction, be- 

 cause it proves the absence of repulsion ? 



Since there is no permanent quality observed in the parti- 

 cles of ponderable matter, inconsistent with their exercising 

 attraction, and as it would be unphilosophical to suppose 

 more causes than are necessary to explain the phenomena, 

 so it would be unreasonable to ascribe their attractive power 

 to an extraneous principle. I allude here to attraction of 

 cohesion, or gravitation. That chemical affinity is much un- 

 der the influence of the electric fluid, is now generally ad- 

 mitted. But to return to the critique. 



" Will Dr. Hare explain the fact that caloric sometimes increases 

 the attraction of bodies for each other ? " What would he say of 

 the fact, that the attraction of two gases, is sometimes increased 

 by heat ?" 



I will not undertake to explain that, which does not occur. 

 When a mixture of hydrogen and oxygen gas, is heated, it 

 expands. So long as expansion continues, it is obvious that 

 caloric does not increase attraction. At the temperature of 

 ignition the heterogenous particles combine, and an explo- 

 sion ensues. 



Thus at the same moment that the simple atoms unite, the 

 compound atoms, formed by their union, separate explosive- 

 ly. The elevation of temperature does not therefore increase 

 attraction, it only favors the union of heterogenous particles, 

 by some unknown process. In a mixture of hydrogen and 

 oxygen gas, the caloric with which they are severally combi- 

 ned, may attach itself to both poles of each simple particle ; 

 after their union, to only one pole of each simple particle ; 



