THE DEVELOPMENT OP ELECTRICAL SCIENCE. 231 



of power, the introduction of Multiphase systems being of considerable 

 importance in this connection. In the direction of high potential and 

 great frequency the work of E. Thomson and Tesla is of great interest. 



Of the application of electricity to the production of light and heat 

 little need be said in this connection. The difficulties to be overcome 

 were largely mechanical, and with the progress made we are all familiar. 



As regards primary batteries there has been, of course, as we all 

 know, considerable progress since the time of Volta. The number of 

 forms brought into use has been enormous and they have been impor- 

 tant in increasing our knowledge of the relative electro motive force of 

 various combinations and in their bearing on chemical knowledge. It 

 can hardly be said that an ideal primary battery has yet been obtained, 

 when we look at the subject from a commercial point of view. Although 

 the subject is not very much to the front at present, however, it is des- 

 tined to come again, and will, I have no doubt, be in a comparatively 

 short time one of our leading industries. 



The work of Plante and of Faure and others on secondary batteries 

 has been of great value commercially. They gave rise to several chem- 

 ical problems, but the main difficulty here also has been of a mechan- 

 ical kind, and they have not added much to the knowledge of electrical 

 laws. 



The transformation of alternating currents from high to low potential 

 and vice versa, by means of what are commonly called transformers, 

 has shown another remarkable development of Faraday's discovery of 

 induced currents. The application of transformers has made it possi- 

 ble to distribute electrical energy over large areas in a moderately 

 economical manner, and incidentally has led to considerable increase 

 in the knowledge of the magnetic properties of iron. 



One of the most important of the applications of electricity is that of 

 electro-chemistry. The chemical action of the electric spark was noticed 

 by Van Groest and Dieman in 1739 in the decomposition of water. 

 Beccari, about the middle of the eighteenth century, obtained metals 

 from oxides through which the spark had passed, and in 1778 Priestly 

 noted the production of an acid gas when the electric spark was passed 

 through air. Similar experiments were made by Cavendish and Van 

 Marum on decomposed ammonia. It is not, however, until after the 

 discovery of the voltaic cell that the subject of electrolysis really begins. 

 L have already referred to the discovery of Nicholson and Carlisle in 

 1800, and the subsequent work of Davy and of Faraday. The peculiar 

 phenomenon of the appearance of separated elements only at the end 

 plates in the electrolytic cell led to considerable speculation, and was 

 explained by Grothuss on the supposition that the molecules separated 

 into two parts, one positively and the other negatively electrified, and 

 that these parts formed a chain between the plates along which chem- 

 ical action traveled by a continual interchange of mates, the end parts 

 going to the plates. This theory was held for many years, and is still 



