130 ELECTRICAL ADVANCE IN THE PAST TEN YEARS. 



metal is then collected and cast iuto ingots for shipment, or is rolled 

 into sheets or rods, or drawn into tubes or wire. 



Works for the production of metallic sodium and other metals sim- 

 ilarly depend upon the decomiDositions effected by the electric current. 



Solutions of ordinary salt or brine are electrolyzed on a large scale 

 in extensive works established for the purpose. The chlorine of the 

 salt is used with lime to make bleaching powder, so important an agent 

 in paper making and textile industries. The sodium of the decomposed 

 salt goes to form caustic soda, which is the base of soap, and is emi>loyed 

 in many manufactures. 



The very high temperature which exists in an electric arc, or between 

 the carbons of an arc lamp, has in recent years found application in 

 the manufacture of another important compound, which was formerly 

 but slightly known as a chemical difficult to prepare. Carbide of cal- 

 cium is the compound referred to, and large works for its production 

 exist at Niagara. Here again, as in the carborundum works, raw 

 materials of the simplest and cheapest kind are acted upon in what 

 may be termed an electric-arc furnace. Coke, or carbon, and lime are 

 mixed and charged into a furnace in which an enormous electric arc is 

 kept going. The carbons in an ordinary arc lamp are usually less than 

 one-half inch in diameter, or they have a section of less than one-fifth 

 of a square inch, while in the carbide of calcium furnaces the section 

 of the carbon may be upward of half a square foot. The light of the 

 enormous arc produced is, however, smothered, so to speak, in ])ow- 

 dered lime and coke — the raw materials mentioned above. The 

 imi)ortance of carbide of calcium rests in the fact that, by contact with 

 water, it produces acetylene gas. The illuminating power of this gas, 

 when burned, is its remarkable j)roperty. 



It will be seen that the metallurgical and chemical developments at 

 Niagara are the direct outgrowth of electrical utilization of water 

 power. With many water powers, however, the outlet for the applica- 

 tion of the electrical energy exists many miles away from the place at 

 which the water power is found. Even at Niagara there is an example 

 of the beginning of long-distance transmission, by a high-pressure line 

 extending to Buffalo and delivering electric energy to an electric station 

 there. 



In this case "step-up" transformers, as they are called, are employed 

 at the Niagara power plant to step up or raise the electrical pressure or 

 potential from that given by the dynamos to that required for the trans- 

 mission to Buffalo. This transformation is from about 2,500 up to 

 10,000 volts. At the Buffalo end the reverse process is carried on by 

 " step-down" transformers, and the energy is delivered to the trolley 

 lines at about 500 volts. At Buffalo the " step down " in pressure is 

 accompanied by a conversion of the alternating current into a contin- 

 uous current in one direction, or a direct current. It would require too 

 much space to explain the meaning of these technical designations of 



