The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

PARADOX II. That a lighter fluid may gravitate or weigh upon a heavier. [paradox 2]

The truth of this is evident, since all Bodies have a tendency towards the Center; by which they are always disposed to press downwards, tho' sometimes they have a respective Levity, as when a piece of Wood emerges in Water, yet nevertheless that relative Levity argues not that it hath no weight at all, since tho' when a Man stands in a pair of Scales and lifts up a weight, notwithstaning the Ascent of the weight he will perceive a manifest tendency of it down∣wards.

But to make it more plain (See Plate 2d. Fig. 2.) where supposing a Cylinder of Water I G,* 1.1 to be immersed in Oyl of Turpentine to the immaginary Surface E F; the Water in the Pipe I H being heavier in Specie than the Oyl, it will equally ponderate upon the Surface E F as the lighter Oyl K E L I, and if the Pipe be immersed deeper, the Cylinder of Water be∣ing not equiponderant with the extenal Oyl, the Oyl will, tho' a lighter Body in Specie, rise in the bottom of the Tube and buoy up the Water.

Again the Bubble X which consists of a Glass heavier than Water and Air which is lighter;* 1.2 or partly of Water it self which is specifically as heavy, as long as the whole aggregate is

lighter than Water of an equal bulk it will float, but if it grows heavier it will sink, and if any heavy Body presses upon it, which is specifically heavier than Water, by which the included Air may be compressed, the Bubble will subside, but when that Pressure is taken off, and the Air ex∣pands it self again, it will as soon emerge, the Water that was before sucked in being by that means expelled.

But for a further Confirmation of this second Paradox, I shall add the following Experiment, viz. That having put a Glass-Bubble pretty well poised, into a Tube filled within a foot of the top with Water, it swam there, till a good deal of Oyl of Turpentine was poured upon the Water, but then more Water being forced into the Bubble by the weight of the incumbent Oyl, it presently subsided; but when part of that Oyl was taken off, the spring of the Inter∣nal Air forcing the impressed Water out a∣gain, the Bubble presently immerged. And,

For a further Confimation of this Paradox as well as the first, I shall add, that a Bubble swimming in a Tube, as in the former Experi∣ment, tho' depressed to the bottom by a Wier, yet when that Pressure is taken off again it will rise up as before; but if it be held under Water till more is poured in, and till it rises about a foot above it in the Tube, the weight of the incumbent Water will depress it, but if that Water be gradually taken off, the Bubble will presently emerge.

If it should be asked why in these Tryals I did not make use of Oyl of Tartar per Deliquium, instead of Water? I shall answer, That in such

slender Pipes as the first Experiment was made in, as the Oyl of Tartar flowed down one side, the Oyl of Turpentine would rise on the other; which makes me wonder that Monsieur Paschall should teach, that if a Tube filled with Mercu∣ry be immersed fourteen foot under Water, if the Tube be fourteen foot long, the Mercury will not wholly run out, but continue to the height of a foot in the bottom of it; and I the more wonder at it, since probably the Impetus would make it descend; and since the like would not succeed with much more favourable circumstances, betwixt Oyl of Turpentine and Oyl of Tartar.

Notes

• * 1.1

  See Plate 2. Fig. 2.
• * 1.2

  See Plate 2. Fig. 3.