Uses
The amount of electricity that has passed through the system can then be determined by weighing the cathode. Thomas Edison used voltameters as electricity meters. (A Hofmann voltameter cannot be used to weigh electric current in this fashion, as the platinum electrodes are too inert for plating.)
A Hofmann voltameter is often used as a demonstration of stoichiometric principles, as the two-to-one ratio of the volumes of hydrogen and oxygen gas produced by the apparatus illustrates the chemical formula of water, H2O. However, this is only true if oxygen and hydrogen gases are assumed to be diatomic. If hydrogen gas were monoatomic and oxygen diatomic, the gas volume ratio would be 4:1. The volumetric composition of water is the ratio by volume of hydrogen to oxygen present This value is 2:1 experimentally,this value is determined using Hofmann's water voltameter.
Read more about this topic: Hofmann Voltameter