Anyone possessing a battery having an electromotive force of from 4 to 20 volts can perform the following experiment, which is particularly interesting on account of the variation of results with apparently the same conditions.
Immerse two pieces of brass in a strong solution of common salt and water. Connect one piece to the positive wire and the other to the negative, taking care that the brass pieces do not touch each other.
After the current has passed one or two minutes, the solution will become colored, and if the process is continued a colored pigment will be precipitated. The precipitate varies considerably in color and may be either yellow, blue, orange, green or brown, depending on the strength of the current, the strength of the solution, and the composition of the brass.
Illustration: How Wires are Connected