2. The fecond is, that in Plants there is made a feparation of some of the most fimple Principles, like that which the Fire caufes in Saltpetre and in Vitriol, when it feparates from them Spirits or Strong Waters; and thefe feparated Principles may cause in the Stomach very nigh the like Effects to thofe caufed by acid Spirits, which are drawn by the force of Fire. Or,

3. That Plants make fuch exact unions of fome of these Principles as the Stomach of Animals can no longer difunite, in order to form other unions proper for their Nourishment, which may give a hurtful quality.

Now if we can prove these two laft, there is no neceffity of receiving the first; for it is a bad method in Phyficks to fuppofe Causes which we do not perceive, when we know others that may fuffice. It feems alfo impoffible that there fhould be these particular Principles in fome Plants; for those which are poisonous, as Hemlock and Aconite, find their Poifon in the fame Earth where the Sugar Cane finds its Sweetness, and fome other Plants their good Qualities.

Now, fince Plants take in indifferently every thing that is diffolved in the Water which touches their Roots, it thence follows that there can be no principle thereby attracted by one Plant, which others do not attract in like manner. You may be convinced that Plants fuck in that which is hurtful, as well as that which is proper for them, by pouring out fome Urine at the bottom of a Lettice or Cabbage, for they will wither in two or three Hours, especially if the weather be hot.

We must conclude therefore, that they are the more or less exact feparations or unions of Principles, and their different proportions produced by different filtrations and divifions through Pores of divers Structures, which give different qualities to Plants; and it is eafy to prove that thefe Things are fufficient for thefe Effects; and that there needs but a very small change in the compofition and union of Principles to form the most different Compofita. I know feveral Experiments whereon we may found this Hypothefis; I made choice of the following, moft part of which are very common, and whence you may eafily draw inductions neceffary to perfuade your felf of it.

Flints have a very thick coverture which ferves as a filtre to separate the inflamable from the aqueous humidity which hinders the Fire. Diamonds, and other precious Stones, have alfo certain coverings to filtrate their most pure and tranfparent Parts. Metals are formed much after the fame manner; and for this Reafon Plants may have different Virtues only by the different filtrations of their common Principles.

If we let new Wine ferment of it felf, it lofes all its Sweetness in a little time, especially if we leave the Veffels open; but if we boil it on the Fire, immediately after the Grapes are preffed, the greatest part of the volatile Principles of the Sweetnefs, concentrate and unite with the moft fixed parts of the Wine, in fuch fort that the Sweetness preserves it felf feveral Years.

Having filled two Bottles of the fame fize with new Wine before it had acquired its rednefs, and stopt one of them as clofe as poffible, leaving the other open, I found that the Wine of the latter, after having worked out its froth

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for feven or eight Days fucceffively, was foul and without any Sweetnefs; and that of the former was as clear and limpid as Spring Water, and extremely fweet; and which proceeded apparently from this, that the Wine which was not stopt had let the volatile Parts, whofe union. with fome other Principles caufes Sweetness, agitate and rife up; and that at the fame time. this agitation had hinder'd the grofs Principles from falling in Lees to the bottom; whereas in the fealed Bottle thefe fame Spirits remained without any confiderable motion, which had produced these two Effects, of letting the Lees fall to the bottom, and preferving the Sweetnefs; and these differences, fo great in one and the fame fort of Wine, proceeded only from this, that the one had been well stopt up, the other not at all.

When Wine is made it preferves its goodness a very long while, if the Veffels are well ftopt. up; but if we let it ftand in a Glafs expofed to the Air, it grows eager in a few Hours, though it does not fenfibly diminish in quantity. Now the Qualities of Wine and Vinegar are very different; Wine is more light than Water, Vinegar more heavy; Wine is very nourishing, Vinegar makes one lean and is drying; Vinegar diffolves Bodies which Wine does not. And all thefe different Qualities depend only upon fome light and infenfible feparations of that which was before united.

Medlars are harsh but a Day before they are fweet, and being fo, are fweet and good to eat, though they have not fenfibly diminished of their weight.

If the Points of the Nettles were not visible, fome would attribute the little fwellings it ex

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cites with pain by its touch, to some occult quality, or fome particular Principle which was not in other Plants; and yet thefe points very probably are nothing elfe than a Web or Tiffue of the fame Principles which compofe the rest of the Nettle.

The prickings of the White-thorn are oftentimes very difficult of cure: We may believe that this does not proceed from any venemous Principle, but because the Points are extremely fharp, and strong enough to wound the Nerves and Tendons, which thofe of the Black-thorn and of other Plants can very rarely do: It is for the very fame Reafon that Wounds made by Needles are more dangerous than thofe made by Pins; whence we may conclude, that acrimony, acidity, bitterness, fweetnefs, &c. proceed not from different Principles, but from their more or lefs exact mixtures or unions, or from the particular Structures and different configurations of their Particles.

If we exactly mingle a certain quantity of Charcoal, Saltpetre, and Sulphur, the Compofition, which we call Gunpowder, produces wonderful Effects and of extraordinary force in Mines, Canons, and several kinds of Wildfire; but if we mix thefe Matters negligently, or if the Dofe of each of them be not of the neceffary proportion, they will have no confiderable Effect.

I have feen a certain Water faid to have been brought from a Spring near the Rhine above Cologne, which had a vinous Taste, and being mixed in Wine made it the stronger; but if we gave it a little vent, it loft almost all its Strength and Flavour, without any apparent diminution of its weight.

Bees

Bees find their Honey in the bottom of Flowers, and we may eafily believe they do fo, fince when we fuck the bottoms of fome certain Flowers, as the Colombine, Clary, Woodbine, Trefoile, Jeffamine, &c. we find in them a fweet Liquor, which is there filtrated and collected together; but if we let Hydromel or Mead, which is a Liquor compounded of Water and Honey take vent, it grows extremely four, becaufe the temperament of thofe Principles which caufe Sweetness is changed, and some of them are feparated by evaporation.

The Root called Maniock in the Antilles Iflands, has a poifonous Juice, but if we prefs out of it fome part of this Juice, and boil the reft, the Bread that is made of it, which is called Caffave, is very good and nourishing.

From thefe Experiments it follows, that we must not attribute to any particular Principle in a Plant that which caufes Poifon, Purgation, &c. but only to the different unions and feparations of fome parts of the Principles common to all Plants. We may also conclude, that thefe different unions and feparations proceed from the inmoft Structure of each Species of Plants; that is to fay, from the ranging together of feveral little Tubes or Pipes, and as many little Colanders or Strainers, &c. diverfly figured and difpofed after fuch a manner as is proper to produce all the Effects which ought thence to follow,

This Hypothefis being received as the moft probable, it remains now that we examine what Conjectures we may build upon, in order to judge wherein a Plant is beneficial or hurtful.

My Thoughts are, that Obfervations and Experiments oftentimes repeated can only instruct us herein; and thus I prove it.