Page:On the various forces of nature and their relations to each other.djvu/91

are afforded us by the action of heat, and among these one of the most important is that force which we call voltaic electricity, which we used at our last meeting for the purpose of obtaining light, and which we carried about the room by means of these wires. This force is produced by the battery behind me, to which, however, I will not now refer more particularly: before we have done we shall know more about this battery, but it must grow up in our knowledge as we proceed. Now, here (fig. 24) is a Fig. 24.portion of water in this little vessel C, and besides the water there are two plates of the metal platinum, which are connected with the