pure, to ferve for Refpiration, this is generally common to all, except it be taken away by Art, or fouled by fome Accident, or where it cannot have Motion, and in fuch Cafes that Defect puts an immediate ftop to all Motion. 5. Reft or Sleep,

without which in a short Time their Motions are foon difordered, and in a short time after, cease. But as I take the two first to be chiefly concerned in what I am enquiring after, I fhall first confider what concerns them, and the other three only accidentally, or afterwards,

CHA P. III.

The Qualities of the feveral Sorts of Matter put into the Stomach, and of the Juices fecreted into it, out of the Blood.

IN order to have fome Notion of the Operations performed in our Stomachs, it will be neceffary to confider the different Sorts of Matter put or fecreted into them, what natural Qualities they have, what Figures their Corpufcles are of, which of them may be confidered as active, and which as little other than paffive, what VOL. X. B external

Qualities of Water.

external Causes comprefs, move, or affect them, what Motion and Effects thofe Bodies with fuch Qualities and Figures will, when all together, and wrought upon by fuch external Causes, produce one upon another, and upon what contains them.

The feveral forts of Meat we eat and drink, I, fuppofe, are compofed of Corpufcles of Water, Oil, earthy Matter, Salts, Air, Fire, and Cold mashed and mixed all together, and along with them, the Saliva or Spittle fecreted out of the Glands in the Mouth and Throat, and a fubtile Fluid like a Mixture of Salts and Spirits meets them there, which either is fecreted or iffued into the Stomach, or conftantly remains there, and fuch a Quantity of Corpufcles of Fire, as form what we call natural Heat.

The natural Qualities of Water are Gravity and fluidity, whereby every Body, heavier than its Bulk of Water, finks in it, and every one lighter fwims, and when any other forts of Matter are mixed in it, thofe Qualities are encreased or diminish

ed

*Or thus, a lubricating Mucus from thofe of the Fau ces, and a Liquor analogous to that of the Salivary Glands, which is conftantly fecreted, and iffuing into the Stomach, and a Quantity of, s.

ed in Proportion to the Degree of those Qualities in the Mixture. Its Corpufcles are extremely light, small, and capable of being expanded, divided, and carried off by corpufcles of Fire, Air, Spirits or volatile Salts, and are round, finooth, or fo figured that they pervade, but do not wound or cut other Bodies, nor divide the corpufcles of any Body except Salt, but impell what they meet with in Proportion to the force which impells them. Whether the corpufcles of Water be so small, that they can be formed into a fluid fo thin, as to carry Matter to form and nourifh the feveral Tubes of which an Hair is compofed, or whether there be corpufcles of different Sizes in Water, or whether there be fluids, whose corpufcles are smaller than thofe of Water, mixed in it, and other fluids, to which Names are given, I am not certain.

Thofe (Qualities) of Oil are Fluidity of Oil. and Gravity, fome forts have more, and fome lefs. But any fort, Fluidity in a much less, and in moft forts, Gravity in a leffer Degree, Bulk for Bulk, than Water. However its Corpuscles are figured, they are light, fmall and capable of being expanded by Fire, Air, &c. but not eafily divided or driven off in Steam, without a B 2 confiderable

Of Vege

ter.

confiderable Proportion of Fire; not capa ble of wounding or dividing other Bodies, but of intangling with one another, and with the Corpufcles of any folid Body; capable of infinuating themselves into the Pores of moft Sorts of Bodies, not capable of being mixed or intangled with the Corpufcles of any Fluid: But I think fheaths, entangles, and contains, or admits a greater Quantity or Proportion of Corpufcles of Fire, than any other Fluid or Body, as appears when it is fired; and from the degree of Heat it takes to makę it boil,

Earthy or vegetable Matter has Gravity table Mat-and Solidity, and fome forts of it Elafticity. In Mafs, fome forts have more Gravity than Water, and fome lefs, in Corpufcles nearly the fame; and 'tis most likely they are flat, thin or fibrous, framed to compofe the Parts of our Bodies, not capable of wounding or dividing, but of adhering to one another, or to other Bodies; liable to be divided by Corpufcles of Fire, or Salts, and fo light as to be born along with Corpufcles of Fire, volatile Salts, and Air.

Of Salts. Salts have Solidity and Gravity. In Mafs, moft Sorts have more Gravity than Water; in Corpufcles fome nearly the

fame

fame. Some which are lighter than, or will swim, or rife in the Air, or be elevated by the Heat of the Sun and Air, which I take to be much the fame as Fire, but fomething larger, because Glass will let go Fire and hold them, and may be called vo◄ latile active Salts; and fome which the Heat of the Sun and Air cannot move or bear off, and may be called fixed Salts. Some Sorts of them are blunt or fheathed; others matted, or they appear to be fo; but moft Sorts are pointed or figured, fo that one Sort or other, or a Mixture of fome Sorts of them, will divide the Corpufcles of moft Sorts of folid Bodies, fome in the Fluid of Water, fome in the Fluid of Air. Their Corpufcles are liable to be divided, fome by Fluids and fome by Fire; they are capable of adhering to one another, and to other Bodies, and confequently those which are lighter then Air or Water, are able to make Corpufcles of other Bodies or Fluids of greater Gravity, then the Fluid which they are contained in, fwim in it with them; And those which are heavier, to make other Corpufcles of leffer Gravity than the Fluid in which they are contained, fink in it with them. Whe ther each fort of Spirits be compofed of a distinct Species of Corpufcles, or they B 3

are