264 



ELECTRICAL ENERGY, STORAGE OF. 



desh on the O rentes to the JEgean Sea; that 

 from the seventeenth century to the twelfth 

 century B. o., they were the leading power of 

 Western Asia, holding the balance of power 

 between Egypt on the one side and Assyria on 

 the other ; and that it was through them that 

 Assyrian civilization was transmitted to the 

 Phoenicians and thence to the Western nations. 

 Their capital, Carchemish, was identified by 

 Mr. J. H. Skene and Mr. George Smith, during 

 the last expedition of the latter gentleman to 

 the East, at Jerablis, on the Euphrates River, a 

 short day's journey south of the town of Bir- 

 edjek. This city gave its name to the Mina of 

 Carchemish, which was for centuries the stand- 

 ard weight throughout Asia Minor, and is men- 

 tioned in the Assyrian inscriptions. A second 

 Hittite capital was identified by Lieutenant 

 Conder in 1881 at Kadesh, on an island in the 

 Orontes River, the present leading topograph- 

 ical features of which are almost exactly re- 

 produced in a representation of the siege of 

 Kadesh on the Egyptian monuments. Two 

 figures of a warrior carved in the rocks at the 

 pass of Karabel, now known to have been es- 

 tablished by the Hittites as evidences of their 

 dominion, have been identified with the figures 

 described by Herodotus as existing in that re- 

 gion, and supposed by him to have been erected 

 by the Egyptian Sesostris as memorials of his 

 conquest. 



The Egyptian and Chaldean monuments 

 and inscriptions, revealing purer religious no- 

 tions and higher moral principles, and display- 

 ing better taste in design and greater skill in 

 execution the further back in antiquity we 

 trace them, demonstrate that, among historical 

 nations at least, the earliest generations were 

 equal, if not superior, in spiritual discernment, 

 intellectual capacity, and the essentials of civ- 

 ilization, even if they had acquired less of the 

 knowledge that comes from observation (which 

 is not shown), to those which succeeded them. 

 Not till the period of the bloom of the Greek 

 intellect in the age of Pericles do we find evi- 

 dences of as high a civilization as prevailed in 

 the first six Egyptian dynasties and in the earli- 

 est Chaldean empire. 



ELECTRICAL ENERGY, STORAGE OF. The 

 importance of a thoroughly commercial secon- 

 dary or storage-battery to the future industrial 

 development of electricity can hardly be over- 

 estimated. Without it, the current generated 

 by the dynamo-machine must be used at the 

 time and rate of production ; but with it, this 

 is no longer necessary, as the energy stored up in 

 it by the primary current may be utilized with- 

 in certain limits at any time and rate desirable. 

 Further than this, it allows of electricity being 

 used under circumstances inadmissible with 

 currents direct from a machine, and also en- 

 ables the current to be generated by various 

 sorts of motors which can not well be used 

 when the current is to be directly applied. It en- 

 ables us further to practically convert currents 

 of high tension, which are the most economi- 



cal to transmit to a distance, into those of 

 low tension suitable for domestic and indus- 

 trial use, and thus becomes a very important 

 factor in any extensive system of distribution, 

 and in the transmission of power. 



The possibility of storing the energy of an 

 electric current, by means of such a battery, 

 depends upon the fact that the electric battery, 

 like the dynamo-machine, is reversible. As is 

 well known, a dynamo-machine may be used 

 either to generate a current when mechanical 

 power is spent in rotating its armature, or in 

 producing mechanical power when a current 

 is caused to circulate in the coils of its arma- 

 ture. Similarly, a voltaic cell may be made to 

 yield a current of electricity by the perform- 

 ance of chemical work, and then to do chemical 

 work by the expenditure of electrical energy 

 upon it. In the ordinary voltaic cell, the cur- 

 rent is due to the chemical changes undergone 

 by certain materials, commonly zinc and acid. 

 If we burn a piece of zinc in the air, that is, 

 allow it to unite chemically with oxygen, its 

 store of energy runs down and manifests itself 

 as heat, just as the store of energy in coal is 

 given out as heat when the coal is burned. In 

 the electric battery, however, the zinc is 

 burned indirectly, and a part of its energy be- 

 comes available for the maintaining of an elec- 

 tric current. When the zinc has united with 

 the acid to form sulphate of zinc, its store of 

 energy becomes exhausted, and further work 

 can be obtained only by a continued supply of 

 the metallic fuel. If there were no other way 

 of renewing this supply of fuel except by the 

 direct furnishing of more of the metal, such a 

 battery would be useless for any purposes re- 

 quiring a considerable expenditure of energy, 

 owing to the high price of the zinc as compared 

 with coal. There is, however, another way. 

 In the case of coal, there is no way of sepa- 

 rating the carbon from the oxygen with which 

 it has combined in combustion, and our supply 

 of energy can therefore only be maintained by 

 keeping up the supply of the coal. In the case 

 of an electric battery, however, it has been dis- 

 covered that, after the zinc has combined with 

 the oxygen of the liquid, it can be recovered 

 from its solution and again deposited in the 

 metallic form, so as to be again available as a 

 source of energy. To recover this fuel, it is 

 only necessary to send a current of electricity 

 through the battery in the opposite direction 

 to that taken by the current furnished by the 

 battery, when all the operations of the battery 

 will be reversed, and it will again be in a condi- 

 tion to furnish a current. To separate the zinc 

 from the oxygen with which it is combined, 

 of course requires power, and if to exert this 

 power it were necessary to consume zinc in 

 another battery, there would be no gain. But 

 we are not compelled to do this. We can use 

 the vastly cheaper energy of coal to generate 

 our current, through the medium of the dy- 

 namo-machine, and thus produce our battery- 

 current at a cost within the limits of economic 



