E'LECTROPH'ORUS (Neo-Lat.. from Gk. 3jx00-pop. rickiron. amber -rpopos, -phoros, bear ing, from cpepftp. idurcii), to bear). This appa ratus consists of a circular disk of hard rubber. vulcanite. shellac, or other insulating material on a metallic surface or form, and a movable metal cover with an insulating handle. The disk is first negatively electrified by being struck briskly with a (oxtail or •atskin, and then the metal cover is placed on it. The next step is to touch the cover with the finger, which may produce a slight spa rk, and t hen grasping the lating handle to raise it. keeping it parallel to the face of the disk. If presented to the finger or any body in contact with the ground. a spark will ensue, and this can be secured for a number of times by simply placing the cover on the disk. touching it with the linger, and ing. This can be repeated until the disk loses its charge by leakage into the air. The tion of the depends upon induction, and the underlying principle is the same as in the electrical machine and other electrical ratus. \\lien the vuleanite or shellac is rubbed it
is negatively charged, the charge residing what below the surface. NOW, W11011 the cover is put on, the negative eha•ge of the disk acts on the plate inductively, attracting the positive tricity to the lower side and repelling the tive to the upper side. \\lien the finger is brought into contact with the nnital it affords all tunity for this negative electrieity to escape to the ground. and leaves the cover with a positive eliarg..e which is held bound. liaising the cover 1111W positively charged. and bringing it near some object in connection with the ground. we have a sharp spark as the «quilibrinin is restored and the plate discharged. The electrophori's can he used to charge bodies and perform a number of experiments in frictional electricity. See o