Communicating Vases.—Employ a tube of a large diameter; terminate one of its extremities with a funnel, fashion the other like the neck of a bottle; and bend the tube into the shape shewn by [pl. 4], fig. 11. Then twist some other tubes into various forms, according to the end you propose to attain, and adjust these tubes to the neck of the large tube by means of corks, which have holes bored through them. In this manner an exchange of tubes is provided for various experiments.
Dropping Tubes.—The name dropping tube is given to an instrument of glass which is very much employed in chemistry, for the purpose of transferring small quantities of liquor from one vessel into another, without disturbing either of the vessels. Dropping tubes are made of a great variety of forms and sizes, according to the purposes to which they are intended to be applied.
Blow a bulb between two points, and then, before the glass has regained its consistence, lengthen the bulb into an oval form. Cut and border the two points.
If the bulb, or reservoir, is to be so large that it cannot be formed at the expense of the thickness of the tube, and yet be sufficiently strong, it must be blown separately from a larger tube, and then soldered to two smaller tubes, one of which should have a certain curvature given to it. See [pl. 2], fig. 20.
Sometimes a dropping tube is employed to measure small quantities of liquid. In this case the point should be drawn off abruptly, and the scale should be marked on the shank or tube with spots of black enamel.
[Pl. 2], fig. 21, represents a peculiar variety of dropping tube employed in some experiments. It is made in the same manner as the common dropping tubes, excepting that, when the tail is formed, it is sealed at the extremity, bent there into a ring, and then pierced at A.
[Pl. 3], fig. 26, represents another variety of dropping tube, a description of which is unnecessary.
Fountains.—It will readily be understood by those acquainted with the construction of hydraulic apparatus, that, by means of a judicious arrangement of glass tubes, a great variety of fountains may be produced. The following are given as examples.