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

CHAP. II. New Experiments about the Pressure of the Air's Spring on Bodies under Water.

* 1.1TO shew that the Spring and Weight of the Air hath manifest effects on Bodies sepa∣rated from an immediate contact by the Inter∣position of Water, I shall subjoyn the following Experiments.

EXPERIMENT II.

We luted the neck of a Vial, which was ca∣pable of containing above a point of Water, upon that pipe which conveys Air out of the Receiver into the Pump, which being done, we whelmed over this Receiver our large one, and having poured in a sufficient quantity of Wa∣ter, we closed it up with the Turn-key, that no Air might get out that way, and then the Air being exhausted out of the Vial, if flew in∣to a great many peices, the sides of the Glass being not able to resist the Pressure of the Air,

that lay upon the Surface of the Water in the large Receiver.

EXPERIMENT II.

The greatest part of the Air being squeezed out of a Bladder, and the Bladder tyed to a weight, which kept it something below the Sur∣face of Water contained in a wide-mouth'd Glass; this being convey'd into a Receiver, the Air in the Bladder expanded, as the Air on the Superficies of the Water was extracted.

EXPERIMENT III.

A Brass Plug being fitted to a Cylinder which was closed with a Plate of the same Me∣tal at one end; we put a Bladder half blown into the Cylinder, and placing the Plug upon it, with a weight of a Conical figure upon that; we poured so much Water into the Receiver in which it was placed, as covered the top of the Conical weight, but left the Ring which was fixed to the top of it, and which was fastned to the Turn-key by the help of a string; and things being thus ordered, when the Air above the water was considerably exhausted, the Spring of the Air in the Cylinder rais∣ed the Plugg and Weights a considerable height, tho' the whole weight amounted to twenty eight pounds.

EXPERIMENT IV.

A Glass Vial being closed with Cement, and immersed in a deep Brass Cylinder of Water, this was convey'd into our Receiver, and when the Air which pressed upon the Water was drawn off, the Vial in the bottom of the Water was violently shattered in pieces by the Spring of the included Air, for want of a sufficient Pressure of the Air incumbent on the Water, to resist the force of that Spring.

EXPERIMENT V.

To shew that the Expansion or Rarefaction of Air increases not the positive Levity of Air, we suspended a Bladder half full of Air, with a Counterpoise, at a ballance in our Receiver, and tho' when the Air was ex∣hausted, the Bladder was sufficiently distended; yet it seemed to retain the same weight, whe∣ther dilated or contracted.

Notes

• * 1.1

  The Pres∣sure of the Air's Spring on Bodies under Wa∣ter.