a a. A finger glass with two holes drilled to pass the wires through, which are imbedded in cement up to the platinum plates. b b. Glass tubes, closed at one end and open at the other, which are placed over the platinum plates to receive the liberated oxygen and hydrogen. The scale at the side shows the respective volumes of two of H to one of O.
To measure the quantity power of the voltaic battery, an important instrument invented by Faraday is used. It consists of separate platinum plates cemented in a wooden stand, and over which a capped air-jar with a bent pipe is also cemented. This apparatus contains dilute sulphuric acid of the same strength as that used in the battery under examination, and by taking the time, the quantity of the mixed oxygen and hydrogen gases producible by a battery per minute is accurately determined, the gases of course being collected in a graduated jar. (Fig. 184.)
Fig. 184.
a. Gas jar with cap and bent tube passing to the graduated tube c; the jar is cemented in the same stand which carries the connecting cups, wires, and platinum plates, which are bent round each other to improve the action of the voltameter.
Fifth Experiment.
By grouping the simple circles forming a voltaic battery in various numerical relations, the quantity and intensity effects are modified.
Thus, if a series of thirty pairs of Grove's battery are all connected together in consecutive order, the smallest quantity and the largest intensity effect is produced.
If changed to two groups of fifteen each, the quantity is doubled—that is to say, it will produce double the quantity of the mixed gases from the voltameter with half the intensity.