clog'd, than is in the Part we touch it with, the Corpufcles iffue thence into the Part, caufe a Sense of Heat, and so on the contrary. The Corpufcles of Fire mixed or entangled with Water, and most other forts of Fluids, except Oil, can act in Fermentation, but mixed with any Fluid except Oil or Spirits, they cannot act in the Air, till most of the Fluid be exhaled, or born off by Fire or Heat, and the Fuel be almoft dry, and doubtless as the Moisture is exhaled out of any Body in the Air, and the Pores contracted, Corpuscles of Fire, volatile Salts, &c. enter and lodge in them.

The feveral Ducts to the several Glands in the Body, are proportioned each to admit, and the Paffages out into the Blood to retain, each, Corpufcles of different Magnitudes or Figures, to form Juices of different Confiftencies and Qualities; as the Juices which fupply the Eye, Mouth, Gall, Stomach, &c. and perhaps the Brain to fupply the Nerves with fine Steam. And the Capacity of the Glands are proportioned, each to contain fufficient Quan→ tity and their Mouths, outward Ends of Valves, to discharge fufficient Quantity, each for their refpective Ufes; and they are fecreted in Proportion to the force of

the

the Steam, and the Supply of it; in the opening of the Pores or Valves in any Part, which gives way for the Steam to drive out the Juices in the Glands next adjacent, along with it through the Skin or that Part, either without, or in the Mouth, Stomach, &c. till the Stock in the Glands be fpent; and after that only Steam, and fuch a Quantity of mixt Juices, as can be conftantly fecreted, till fhutting their Mouths ftop the Discharge, and they be by Degrees replenished; and this is done involuntarily, fleeping or waking, though perhaps the Will has fome Power to direct or encrease the Force of the Steam, especially that in the Nerves, waking more than fleeping. This Operation of fecreting the Juices of feveral forts, at the Glands, in the several Parts, will not appear fo difficult, if their Number and Difpofition be well confidered; nor need there be fo many Corpuf cles of leffer Sizes returned out of the Glands into the Blood, for there is fuch an infinite Variety of Ducts and Glands, and fuch an infinite Difproportion in Number, between the fmaller and the greater Veffels or Gland, that if one was to imagine the Stomach and Guts clean, and the Blood and Juices were all difcharged

charged into them, and the Blood-veffels were to stand empty and diftended, and the Blood and Juices were equally mixed, and fo mixed, iffued out into the Bloodveffels, &c. the thinneft Parts or Juices would, as they paffed the larger Veffels, find their Way into the infinite Number of small Outlets, and the Blood and Juices in the larger Veffels would almost immediately be of the fame Thickness they are at prefent, except where the Ducts to the Glands are fo ftraight, that they are defigned to fill them but flowly, fo that the Glands may be stocked when there fhall be Occafion to discharge the Juices for diffolving the Meat, discharging the Excrements, and for fuch Uses as they are not conftantly wanted, but at fome Distances of Times: And when all act regularly this must be done, in every Circulation of the Blood, at least a confiderable Proportion of it. This might be demonftrated; If a Pipe of a great Length, were bored in the Sides with Holes of different Sizes, proportioned in Number to the Quantity, and in Dimenfion to the Sizes of the Corpufcles of feveral forts of Liquor, and thofe Liquors were all mixed together, and one fort more, whose Corpuscles were too large to pass.

any

any of the Holes, were forcibly pumped in, and the Pipe forcibly compreffed, the Liquor whofe Corpufcles were largest, would be found feparated at the far End.

CHAP. XIII.

The Contrivance and Ufes of the Bags, Valves, and Stops of the Stomach, the feveral Parts of the Guts, &c. the Time when, and Manner how thofe Bags and Tubes are extended or contracted, their Valves opened or fbut and how they discharge the Excrements downward, all involuntarily.

IN Order to know what is done in the Guts, we ought firft to confider the Form of their feveral Parts, the feveral Divifions made in them by Valves or Stops, the Manner how each is diftended or contracted, how the Valves between each Part are shut or opened, the Confequences of extending or contracting each Part, and of fhutting or opening each of the Valves or Stops which divide the Parts. Firft, The Gullet has one or more Valves at the upper End, called the Pharynx, fo contrived, that they

they refift ftrongly, and hinder the Steam, Meat, Drink, &c. from afcending out of the Stomach, unless they be weakened by: emptying the Glands in them, but open voluntarily and eafily, to let the Preffure of the Jaws or Air force down the Meat or Drink, and even whilft they are going down, that the Steam fhould not get Vent; for we cannot keep it open, and pour down a Fluid continually till the Stomach be full, but fo much only at once, as the Space between the Root of the Tongue and that Valve will contain, and then shut up the Paffage at the Root of the Tongue, which at once opens the other, and preffes the Fluid down, and fo alternately. And the Preffure of the Air has fome Share in the Action, for if one empty one's Lungs of the Air, take one's Mouth full of Fluid or Meat, and shut one's Mouth and Nofe, one can fwallow little or none of the Fluid or Meat, but prefs it down in fmall Quantity at once by the Strength of the Jaws, and the Remainder of the Air left in one's Lungs. It will be hard to ascertain the feveral Pofitions of the Stomach, and the feveral Parts of the Guts, because the Moment a Body is opened, the Steam in them extends them, and difplaces every

Part.