Page:Various Forces of Matter.djvu/123

Rh I have shaped into a cap for it and made dry. I will put this shellac into the flannel, and here comes out a very beautiful result. I will rub this shellac and the flannel together (which I can do by twisting the shellac round), and leave them in contact; and then, if I ask, by bringing them near our indicator, what is the attractive force?—it is nothing! But if I take them apart, and then ask what will they do when they are separated,—why the shellac is strongly repelled, as it was before, but the cap is strongly attractive; and yet if I bring them both together again, there is no attraction—it has all disappeared [the experiment was repeated]. Those two bodies therefore still contain this attractive power—when they were parted it was evident to your senses that they had it, though they do not attract when they are together.

This then is sufficient in the outset to give you an idea of the nature of the force which we call. There is no end to the things from which you can evolve this power. When you go home take a stick of sealing-wax—I have rather a large stick, but a smaller one will do—and make an indicator of this sort (fig. 35).