348 THE CANADIAN NATURALIST. [Vol. X. 



The deposition of metals from their solutions is perhaps the 

 oldest of all useful applications of the electric current, but it is 

 only in very recent times that the dynamic current has been 

 practically applied to the refining of copper and other metals, as 

 now practised in Birmingham and elsewhere, and upon an excep- 

 tionally large scale at Ocker, in Germany. The dynamo machine 

 there employed was exhibited at the Paris Electrical Exhibition, 

 its peculiar feature being that the conductors upon the rotating 

 armature consisted of solid bars of copper 30 m. m. square, in 

 section, which were found only just sufficient to transmit the 

 large quantity of low tension necessary for this operation. One 

 such machine consuming -A-horse power deposits about 300 kilo- 

 grammes of copper per 24 hours ; the motive power at Ocker 

 is derived from a waterfall. 



The electric energy may also be employed for heating pur- 

 poses, but in this case it would obviously be impossible for it to 

 compete in point of economy with the direct combustion of fuel 

 for the attainment of ordinary degrees of heat. Bunsen and 

 Ste.-Claire De Ville have taught us, however, that combustion 

 becomes extremely sluggish when a temperature of 1800° C. has 

 been reached, and for effects of temperatures exceeding that 

 limit the electric furnace will probably find advantageous appli- 

 cations. Its specific advantage consists in being apparently un- 

 limited in the degree of heat attainable, thus opening out a new 

 field of investigation to the chemist and metallurgist. Tungsten 

 has been melted in such a furnace, and 8 pounds of platinum 

 have been reduced from the cold to the liquid condition in 20 

 minutes. 



The largest and most extensive application of electric energy 

 at the present is to lighting ; but, considering how much has of 

 late beeu said and written for and against this new illuminant, 

 I shall here confine myself to a few general remarks. 



The principal argumeut in favor of the electric light is furnished 

 by its immunity from products of combustion which not only heat 

 the lighted appartments, but substitute carbonic acid and dele- 

 terious sulphur compounds for the oxygen upon which respira- 

 tion depends ; the electric light is white instead of yellow, and 

 thus enables us to see pictures, furniture, and flowers as by day- 

 light ; it supports growing plants instead of poisoning them, and 

 by its means we can carry on photography and many other 

 industries at night as well as during the day. The objection 



