Mixture, and its Effects. 93 



x 



to explain, because we can scarcely find any 

 thing else with which they can be compared. 

 If a mechanic removes a prodigious rock by the 

 force of one man, it will be cause of wonder to 

 one unacquainted with the mechanical princi- 

 ples; but on examining the instruments by 

 which this effect is wrought, we shall find that 

 the whole .depends upon certain fixed laws of 

 mechanism and motion. If the chemist re- 

 moves a rock of the same magnitude by a small 

 quantity of nitre, sulphur, and charcoal, we shall 

 not so easily understand the manner in which 

 the effect is produced. It is more easy to in- 

 crease the number of facts than to explain them. 



After Lord Bacon, chemistry became more 

 known, and attempts were made for a more 

 rational and popular theory. As mechanical 

 powers are easily understood, we are apt to sup- 

 pose that the action of bodies depends upon me- 

 chanical principles. 



The most popular opinions were, that the 

 powers of bodies depended upon their particles 

 having 'particular figures and motions. Boyle 

 was one of the first who published this opinion, 

 but he did it in a moderate and diffident man- 

 ner. Many after him, however, have extended 

 this application so far as to show the full ab- 

 surdity of it, especially the older French chemists. 

 If we were to consult them upon the first experi- 

 ment we made, they would tell us that the sul- 

 phuric acid (or, as they would call it, the oil of 



