15* 



an infinite variety of circumstances. Thus, changes of 

 weather, even without thunder or lightning, or atmo- 

 spheric electricity, may produce, by uniting occurrences, 

 similar phenomena. 



Dr. E. Clarke, of Jesus College, Cambridge, entertains a 

 different opinion respecting the origin of those substances; 

 and is now employed in preparing a dissertation upon this sub- 

 ject for the Royal Society. The result of this opinion he has 

 communicated, referring to his Memorial for the proofs ne- 

 cessary to establish its truth ; as the work at large is too long 

 for insertion here. He considers all the substances of the 

 mineral kingdom as capable of existing in a solid, fluid, or aeri- 

 form state; according to the predominance of the active or 

 passive principle : that is to say, of the principle of repulsion, 

 or the principle, of attraction. These two powers always coun- 

 teracting each other, have been variously denominated; but 

 their most recent appellations have been caloric, or the fluid 

 matter of heat, and the law of gravity . The last of these was 

 completely developed by Sir Isaac Newton; who determined 

 the agency of the passive principle, or the law of gravity, to 

 vary inversely as the square of the distance from the centre. 

 The first, and perhaps the most important principle, whose 

 agency prevents the particles of the most solid bodies from 

 coming in contact with each other, remains to be developed 

 by the discoveries of future science. One fact respecting it 

 is generally admitted ; that the power of attraction, inde- 

 pendent of its agency, would be infinite. Admitting this 

 truth, we can form no idea of the degree of solidity to 

 which matter so circumstanced might be liable. 



In regions remote from the earth's surface, where light 

 enters into the least combination with matter, and generates 

 the lowest degree of that modification of it, to which the 

 term caloric has been applied, the particles of bodies, result- 

 ing from the decomposition of aeriform fluids, will be 

 brought very near each other; and the consequence must 



