We shall fill some such bubbles with hydrogen gas, instead of atmospheric air, and you will see with what ease and rapidity they will ascend, without the assistance of blowing, from the lightness of the gas.—Will you mix some soap and water whilst I fill this bladder with the gas contained in the receiver which stands on the shelf in the water-bath?
CAROLINE.
What is the use of the brass-stopper and turn-cock at the top of the receiver?
MRS. B.
It is to afford a passage to the gas when required. There is, you see, a similar stop-cock fastened to this bladder, which is made to fit that on the receiver. I screw them one on the other, and now turn the two cocks, to open a communication between the receiver and the bladder; then, by sliding the receiver off the shelf, and gently sinking it into the bath, the water rises in the receiver and forces the gas into the bladder. ([Plate IX.] fig. 1.)
Vol. I. p. 228
Fig. 1. Apparatus for transferring gases from a Receiver into a bladder.
Fig. 2. Apparatus for blowing Soap bubbles.
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