The philosphical and physical opinions written by Her Excellency the Lady Marchionesse of Newcastle.

Chap. 102. Of such sorts of heating Motions, as cause burning, melting, boiling, Evaporating and rarifying.

BUrning, melting, boyling, and evaporating are caused by several motions, or several degrees or temperaments of matter.

And though burning, melting, boyling, and evaporating, are caused by expulsive and dilating motions, yet al dilative and expulsive motions, work not after one and the same manner, but according as the matter is; As for example, leather doth not burn as wood doth, yet both are dissolved by an expulsive motion.

Besides, some figures do dissolve into flame, others moul∣der away into dust, and never flame, as stone, and many more examples may be given, but most commonly all burning motions do pierce, or shut, or wedge, in sharp tootht, or poin∣ted figures; into those figures they work upon, and then it dis∣solves it by expulsions; for those sharp pointed figures, help motion to loosing, and unbinde those parts that they finde joy∣ned and contracted, that they may more freely separate those parts and dissolve those figures, which as they dissolve the thinner parts, dilate into vapor, the lighter parts flie out into fiery points, which are those we call sparks of fire, but the grosser, and more solid part moulders away into dust and ashes, as being too heavy and solid for the points to spread forth, they can onely as it were chew it between their sharp teeth; for ashes are nothing but chewed wood, yet this manner of chew∣ing doth alter the nature from being wood, or any thing that burns after an expulsive manner, but those fiery motions that onely melt, or rather those figures that are not subject to burn, but onely to melt, is done by a stretching motion, for those motions do as it were thrust out the contracted parts, and cause them to extenuate; but when the fiery moti∣ons cause any thing to boyl, they first stretch out the parts so

far, as causeth those parts to be fluid, and as it were liquid, if those things were contracted, but if they be liquid and fluid of themselves, they save those fiery motions that labour, and when this motion strives to ascend with those loose parts, the liquor riseth up in bubbles, or waves, but when those fiery motions are over-poured by the weight, they fall back again; thus the weight of the liquor, and the sharp points of the fire strive together, one party striving to ascend, the other to descend, so that those fiery motions, are to pull out, or to bear up, and the watry motion to pull, or presse down, but evaporating, is when the extenuating lines are stretcht so far out, as to break, or the lighter parts are carried away, and dispersed amongst other figures; but all rarifying heats, are caused by slow dila∣ting motions, and not expulsions, for if such sorts of dilations as make rarifying heat, were extended beyond the line of the matter they work on, it alters the nature of the figure, and the motions of that nature; but rarifying heat is an extenuating mo∣tion, spreading parts equally, and evenly, but the farther they are spred, the more hot grows the heat, as neerer to expul∣sion, and though all rarifying heat is in the way of burning, yet not in the manner.

But I must intreat my reader to take notice, that burning motions, make use of burning figures, for all sorts of motions work according to the matter and figure they work on, or in, or to.