fiOOK IL] motion of AVOlCANCfi. 5i6 



gregation do, nor end by bringing the substances ihto contact, 

 as all do, but only raise them, and make them swell without any 

 further effect. Por if the moon raise the waters, or cause 

 moist substances to swell, or if the starry sphere attract the 

 planets towards their apogees, or the sun confine the planets 

 Mercury and Venus to within a certain distance of his mass ;' 

 these motions do not appear capable of being classed under 

 either of those of congregation, but to be, as it were, inter- 

 mediately and imperfectly congregative, and thus to form a 

 distinct species. 



Let the tenth motion be that of avoidance, or that which i« 

 opposed to the motion of lesser congregation, by which bodies, 

 with a kind of antipathy, avoid and disperse, and separate them- 

 selves from, or refuse to unite themselves with others of a hostile 

 nature. For although this may sometimes appear to be an 

 accidental motion, necessarily attendant upon that of the lesser 

 congregation, because the homogeneous parts cannot unite, 

 unless the heterogeneous be first removed and excluded, yet it 

 is still to be classed separately,* and considered as a distinct 

 species, because, in many cases, the desire of avoidance appears 

 to be more marked than that of union. 



It is very conspicuous in the excrements of animals, nor less, 

 perhaps, in objects odious to particular senses, especially the 

 smell and taste ; for a fetid smell is rejected by the nose, so as 

 to produce a sympathetic motion of expulsion at the mouth of 

 the stomach; a bitter and rough taste is rejected by the palate 

 or throat, so as to produce a sympathetic concussion and shiver- 

 ing of the head. This motion is visible also in other cases. Thus 

 it is observed in some kinds of antiperistasis, as in the middle 

 region of the air, the cold of which appears to be occasioned by 

 the rejection of cold from the regions of the heavenly bodies ; 

 and also in the heat and combustion observed in subterranean 

 spots, which appear to be owing to the rejection of heat from 

 the centre of the earth. For heat and cold, when in small 

 quantities, mutually destroy each other, whilst in larger quan- 

 tities, like armies equally matched, they remove and eject each 

 other in open conflict. It is said, also, that cinnamon and other 

 perfumes retain their odour longer when placed near privies and 

 foul places, because they will not unite and mix with stinks. It 

 is well known that quicksilver, which would otherwise reunite 

 into a complete mass, is prevented from so doing by man's spittle, 

 pork lard, turpentine, and the like, from the little affinity of its 



' Observe this approximation to Newton's theory. 



■ Those differences which are generated by the masses and respective 

 distances of bodies are only differences of quantity, and not spccitio j 

 consequently those three classes are only one. £d, 



2 2jf 



