OW all the Causes of Mixture we can conceive of, must, I think, be reduced to these six in general; viz. Congruity, Weight, Compression, Solution, Digestion, and Agitation.
1. §. Congruity, or aptitude and respondence betwixt the Sizes and Figures of Parts to be mixed: whereby Bodies may be truly called the Instrumental Causes of their own Mixture. As when a Plain answers to a Plain, a Square to a Square, a Convex to a Concave, or a Less to a Greater or an Equal, &c. according to which Respondencies in the parts of Bodies, they are more or less easily mingleable.
2. §. Weight, by means whereof all Fluid Bodies, upon supposition of the Congruity of their parts, must unavoidably mingle.
3. §. Compression; which either by the Air, or any other Body, added to Weight, must, in some degree, further Mixture. Because, that Weight it self, is but Pression. For further Proof of all the said Causes, I made this Experiment; Let Oyl of Aniseeds, and Oyl of Vitriol be put apart into the Receiver of an Air-Pump. And, having exhausted it of the Air, let the two said Oyls be then affused one upon the other. Whereupon, First, It is visible, that they here mix and coagulate together; that is, their parts are wedged and intruded one into another, without the usual compression of the Air; for that is exhausted, and therefore only by the Congruity of their receiving and intruding parts; and by their Weight; by which alone they are so compressed, as to make that Intrusion. Secondly, It is also evident, That although they do Coagulate; yet not altogether so much, as when poured together in the same manner, and quantity, in the open Air. Wherefore, Compression, whether made by the Air, or any thing else, as it doth further the Dissolution of some Bodies, so the Mixture of others, and the greater the Compression, the more.
4. §. Solution; For all Bodies mix best, in Forma fluida. And that for two reasons. First, Because the parts of a Body are not then in a state of Union, but of Separation; and therefore, in a more capable state, for their Mixture and Union with the parts of another Body. Secondly, because then they are also in a state of Motion, more or less; and therefore, in a continual tendency towards Mixture; all Mixture being made by Motion. Wherefore all Generations, and most perfect Mixtures in Nature, are made by Fluids; whether Animal, Vegetable, or Mineral. Which is also agreeable to the Doctrine of the Honourable Mr. Boyle, in his Excellent Treatise of the Nature and Vertues of Gems. And it is well known, That Bodies are ordinarily petrified, or Stones made, out of Water. That is, out of petrifying parts dissolved per minima in Water, as both their Menstruum and their Vehicle. Wherefore, if we will talk of making Gold; it must not be by the Philosophers Stone, but by the Philosophers Liquor.
5. §. Digestion. For which there is the same reason, as for Mixture, by Solution. For, First, All heat doth attenuate, that is, still further separate the parts of a Body; and so render them more mingleable with the parts of another. And therefore, Secondly, Doth also add more Motion to them, in order to their Mixture.
6. §. Agitation. Which I am induced to believe a great and effectual means of Mixture, upon divers Considerations. As, First, That the making of Blood in the Bodies of Animals, and the mixing of the Chyle therewith, is very much promoted by the same means; sc. by the Agitation of the parts of the Blood and Chyle, in their continual Circulation. Again, from the making of Butter out of Milk, by the same means: whereby alone is made a separation of the oleous parts from the Whey, and Conjunction of the Oleous together. Moreover, From the great Effects of Digestion; well known to all that are conversant in Chymical Preparations. Which Digestion it self, is but a kind of insensible agitation of the parts of digested Bodies. ’Tis also a known Experiment, That the readiest way to dissolve Sugar in Wine or other Liquor; is to give the Vessel a hasty turn, together with a smart knock, against any hard and steady Body: whereby all the parts of the Sugar and Liquor, are put into a vehement Agitation, and so the Sugar immediately dissolved, and mixed with the Liquor. And I remember, that having (with intent, to make Mr. Matthews’s Pill) put some Oyl of Turpentine and Salt of Tartar together in a Bottle, and sent it up hither out of the Country; I found, that the continual Agitation upon the Road, for three or four days, had done more towards their Mixture; than a far greater time of Digestion alone had done before. And it is certain, That a vehement Agitation, especially, if continu’d, or joyned with Digestion; will accelerate the Mixture of some Bodies, ten times more, than any bare Digestion alone; as may be proved by many Experiments. I will instance in this one. Let some Oyl of Turpentine and good Spirit of Nitre be stop’d up together in a Bottle, and the Bottle held to the Fire, till the Liquors be a little heated, and begin to bubble. Then having removed it, and the Bubbles by degrees increasing more and more; the two Liquors will of themselves, at last fall into so impetuous an Ebullition, as to make a kind of Explosion; sending forth a smoak for the space of almost two yards high. Whereupon, the parts of both the Liquors, being violently agitated, they are, in a great portion, incorporated into a thick Balsam in a moment: and that without any intense heat, as may be felt by the Bottle. And thus much for the Causes of Mixture.