ELECTROCHEMISTRY 



1999 



ELECTROCUTION 



is one of many instances of welding by means 

 of electricity; in welding steel rails the car- 

 riage containing the apparatus for welding 

 moves along the track, stopping at each spot 

 where the work is to be performed. 



In another form of electric welding a cur- 

 rent is caused to flow through the metals, the 



ELECTRIC WELDING MACHINE 

 In the illustration the circular band a Is being 

 welded. The ends to be fused are in contact at 

 the lowest point in. the circle. The machine shown 

 will weld 200 steel bands in an hour, for only a 

 few seconds are required to make an electric 

 weld. A heavy current of electricity at a low 

 voltage is passed through the abutting ends of 

 the metal pieces to be welded, thereby generating 

 heat locally at the points of contact, while at the 

 same time pressure is applied to force the parts 

 together. 



ends to be welded being placed in contact, as 

 shown in the accompanying illustration of a 

 small electric welder. Since the resistance of 

 this contact is very great, intense heat is de- 

 veloped, fusing the metals at the contact and 

 making a perfect junction. E.E.B. 



ELECTROCHEMISTRY , elek tro kern ' is tri, 

 that branch of chemistry in which chemical 

 changes are brought about by electric energy. 

 In the voltaic cell chemical energy is converted 

 into electric energy (see ELECTRIC BATTERY). 

 This electric energy can again be transformed 

 into chemical energy, and this principle under- 

 lies many thriving and important industries. 

 The practical operations of electrochemistry 

 may be considered under two groupsr those 



which cause chemical changes at ordinary tem- 

 peratures, and those in which the changes 

 occur only at the high temperatures possible 

 in the electric furnace. 



A simple illustration of a change of the first 

 sort is found in the analysis of water, or its 

 separation into its component gases, oxygen 

 and hydrogen. Electroplating (which see) is 

 an extensive application of this sort of electro- 

 chemistry. Copper is also refined by the same 

 process (see COPPER, subhead Preparation). 



Metals which are extracted from their ores 

 with great difficulty by ordinary processes are 

 readily separated in the intense heat of the 

 electric furnace. For instance, the production 

 of aluminum on a commercial basis was not 

 possible before the invention of the electric 

 furnace (see ALUMINUM, subhead Its Manu- 

 facture). 



The electric furnace possesses another ad- 

 vantage, that is, its power of separating the 

 decomposed compounds by electric attraction, 

 as in the production of aluminum. The metal 

 when freed from its ore gathers around the 

 anode, or positive pole, in the furnace, while 

 the other substances are attracted to the 

 cathode, or negative pole. In this way many 

 substances in use in the arts are produced, 

 chief among which are carbide, used in the 

 production of acetylene gas; carborundum, a 

 valuable abrasive; caustic soda; chlorate of 

 potassium, and chloride of lime and bleaching 

 powders. An excellent quality of graphite is 

 also manufactured, rivaling that of the best 

 mines. . 



Electrochemistry is a .comparatively new 

 branch of chemical science, and although it 

 has made rapid progress since the beginning of 

 the twentieth century it is doubtless still in 

 its elementary stage. 



ELECTROCUTION, c lek tro ku'shun, a legal 

 method for the infliction of the death penalty 

 by passing through the body of the condemned 

 criminal an electrical current of not less than 

 2,000 volts. Such a strength of current is 

 enough to produce instant insensibility and 

 painless death. After a long investigation by 

 the legislature of the state of New York this 

 method was pronounced more humane than 

 hanging, and it became effective in that state 

 in January, 1889. According to the law in that 

 state, which has been taken as a standard by 

 other states, there must be present at an exe- 

 cution, besides the prison warden, twelve citi- 

 zens, seven deputy sheriffs, two physicians and 

 one or two ministers, as the doomed man may 



