220 Newton*s Letters^ Hypothesis and Experiments 



abounding with particles, to which the former saline particles 

 are more sociable than to the particles of the metal (suppose 

 with particles of salt of tartar), then so soon as they strike on 

 one another in the liquor, the saline particles will adhere to 

 those more firmly than to the metalline ones, and by degrees 

 be wrought off from those to enclose these. Suppose A a me- 

 talline particle, inclosed with saline ones of spirit of nitre, E 

 a particle of salt of tartar, contiguous to two of the particles 

 of spirit of nitre, b and c ; and suppose the particle E is im- 

 pelled by any motion towards r/, so as to roll 

 about the particle c till it touch the particle d, Fig. 4. 

 the particle b adhering more firmly to E than 

 to A, will be forced off from A ; and by the 

 same means the particle E, as it rolls about A, 

 will tear off' the rest of the saline particles from 

 A one after another, till it has got them all, or 

 almost all, about itself. And when the metallic 

 particles are thus divested of the nitrous ones, 

 which, as a mediator between them and the 

 water, held them floating in it, the alcalizate 

 ones, crowding for the room the metallic ones 

 took up before, will press these towards one another, and 

 make them come more easily together: so that by the motion 

 they continually have in the water, they shall be made to strike 

 on one another; and then, by means of the principle in the 

 second supposition, they will cohere and grow into clusters, 

 and fall down by their weight to the bottom, which is called 

 precipitation. In the solution of metals, when a particle is 

 loosing from the body, so soon as it gets to that distance 

 from it, where the principle of receding described in the fourth 

 and fifth supposition begins to overcome the principle of ac- 

 ceding, described in the second supposition, the receding of 

 the particle will be thereby accelerated ; so that the particle 

 shall as it were with violence leap from the body, and putting 

 the liquor into a brisk agitation, beget and promote that heat 

 we often find to be caused in solutions of metals. And if any 

 particle happen to leap off' thus from the body, before it is 

 surrounded with water, or to leap off with that smartness as 

 to get loose from the water, the water, by the principle in 

 the fourth and fifth supposition, will be kept off from the par- 

 ticle, and stand round about it, like a spherically hollow arch, 

 not being able to come to a full contact with it any more ; and 

 several of these particles afterwards gathering into a cluster, 

 so as by the same principle to stand at a distance from one 

 another, without any water between them, will compose a 

 bubble. Whence I suppose it is, that in brisk solution there 



