Bottling it up in the Leyden jar.
The electricity that is collected on the brass receiver can be taken off and be bottled up, as we may say, so as to be convenient for use. This can be done with what is called the Leyden jar, as represented here. This is a glass jar coated inside and out with tin foil to within a few inches of the top. Then there is a knob on the end of a wire that extends down into the jar. Now see how we do this bottling up of the electricity. The knob of the jar is held close to the knob of the receiver as the machine is worked. The electricity, therefore, passes to the knob of the jar, and by the wire to all the inside of the jar where the tin foil is. It can not get outside, because it can not pass over or through the glass.
So, then, the electricity is shut up in the jar, but it is ready to come out when it has a way made for it to come. If the inside foil and the outside foil be connected together by something that will let the electricity pass through it, it will come out of the jar. You can be that something if you please. If you put one hand on the tin foil on the outside, and touch the other to the knob on the end of the wire, the electricity will come out by the wire, and give you a shock in your wrists, and elbows, and chest.
Taking shocks from the jar.
A great many persons can take a shock in this way at the same time. Suppose there are a hundred persons standing in a ring and taking hold of each other’s hands. Let there be two in this ring that do not have hold of each other. Now, if one of these touches the jar on the outside, and the other touches the knob, the whole hundred will feel a shock at the same time, for the electricity will go through them all around the whole ring as quick as lightning, as we say; and it is, in this case, really so, for the electricity is lightning. And so, when in the telegraph the electricity passes along the wire, it takes almost no time for it to go very great distances.
An electrical battery.
Sometimes a great deal of electricity is collected in a number of these jars, which are connected together in such a way that the electricity can be discharged from them all at once. A collection of jars thus connected, as represented here, is called an electrical battery. There is need of great care in experimenting with a battery; for if, when the jars are well filled, they should all be discharged into any one, he would be killed in the same way that one is who is struck with lightning.