On Chemical Philosophy. 427 



duced ; or one substance is dissolved in it and another precipi* 

 tated from it, or drawn in this way and carried in nnither. Hence 

 also it is e\idcr.t from these properties, that by motion, friction, 

 and alterations of arrai'gement, either a ^tipam will be induced, 

 or some di>turbance in its due diffusion: every stream inuuced, 

 motion or chana;e must accumnlate it on one point and abstract 

 so much from another; all distnrbancf, all motion, all change, 

 &c. may be so defined (if any definition diould regard merely 

 effects), from that which gives motion to the fir.>r, germ of vege* 

 tation, to that wliich shakes Etna or convulses the atmosphere 

 round the globe. That such mechanical actions should produce 

 these effects, I conceive is capable of demonstration. The 

 wind blows in a certain direction, and the billows partake of the 

 same course, ^'achinery collects and produces a current of air 

 in the direction of their movements. 



From these properties of this power, then, we perceive that it 

 will both by chemical and mechanical means be put in motion; 

 and if this current is demanded in one way rather than another, 

 or if th'^'-e motions are made in r.^y given and determinate di- 

 rection, — and all motion must tend to some point; — we find also 

 a current proceeding in a certain direction : and hence on these 

 principles we, have the action nf the electric machine. Where we 

 contrive to intercept this fluid so put in motion, we there find it 

 accumulated or in excess; and if in this state we can remove the 

 cause which intercepts, or assist its m.otion by some conducting 

 body, we find it move from this point; and thus v/e perceive how 

 by mechanical contrivances, its concentration upon and radia- 

 tion from substances, the point which is in excess is carried by 

 this excess, and the other which is deficient is drawn towards 

 it ; and hence we have two apparent currents or movements in two 

 opposite directions, bodies and the particles of bodies moved in 

 one way and drawn in another — two different poles, negative 

 and positive, imparting in one direction and drawing in another: 

 if the rubbing body attracts less than the body rubbed, this 

 body is positive, and the other negative; and the contrary when 

 the circunistnnces arc reversed. Hence *' negative and positive 

 are mere relulivc sialcs rif existence," — that positive particles or 

 points which are in excess are carried and draw negative points 

 or particles towards them, or particles which have less than their 

 natural shaie ; and hence, as has already often been repeated, 

 particles unite and separate in the same order under the same 

 circumstances : this order (I shall under Chemical Affinity show) 

 is the mean bctv/ecn the dissimilarity of chemical and the simi- 

 larity of tiie physical qualities: the greater the dissimilarity of 

 the chemical, it is evident, greater nnut be the action — the 

 greater must be the negative and positive state of the particles ; 



and 



