ELECTRICITY, CAUSE OF DEATH BY). The amount of current flowing through the body depends upon the electric pressure or voltage and the resistance of the body. This resistance is mainly the skin or surface resistance, therefore depends upon the nature of the contact between body and electric circuit. When loosely touched with dry hands a 100-volt circuit may hardly give any sensation, while grasped with wet hands a 50-volt circuit may be unbearable. Only at very high voltages the nature of the contact becomes of less importance and the electric cur rent penetrates as arc. Electric pressures below 500 to 600 volts are considered as still safe, since only in cases of exceptionally good contact with such voltages serious results may occur. Much higher voltages are usually, fatal, but instances are on record of contact with 10,000 to 20,000 volts without fatal results, in cases where the duration of the contact has been very brief.
The causes of death by electricity are : 1. The direct effect of large power exerted upon the body, causing destruction by heat, etc., as in electrocution where several horse power are used.
2. Mechanical destruction of vital organs by very heavy discharges, as lightning.
3. Paralysis of the nervous system, stop page of the heart and respiratory organs. In these cases resuscitation by artificial respira tion, etc., when immediately resorted to, is very promising, especially if only respiration has stopped, but the heart is still beating.
Therapeutically electricity is used as stimu lant by its action on the nervous system and for carrying substances through the skin into the body electrochemically. It is very useful in the hands of expert physicians but like any powerful agent, in the hands of a layman, is harmful and dangerous. The electric healing devices advertised broadcast, as electric belts, etc., are mere swindles and without any value. See ELECTROTHERAPEUTICS.
Prospect.— Only the very beginning has been made in the use of electricity as secondary form of power for transmitting energy from its natural source, waterfall or coal mine, to the place of consumption, factory, city, railway. Here very great strides are still to be looked forward to, resulting in a much more efficient use of the stores of energy afforded by nature.
The essential characteristic of modern civiliza tion is the independence of man of his immedi ate surroundings, in the necessities of civilized life. These necessities are materials and energy. The transportation, distribution and supply of materials has been organized in the last century in the system of railway, steamship and other transportation agencies, and the generation, transmission, distribution and supply of energy is now being organized by electric power, in the system or network of transmission and dis tribution lines, which increasingly spread over the country and interconnect the electric power generating stations — steam and hydraulic with the places of energy demand. Only elec tricity can fulfil this requirement of energy supply of bur civilization, due to the high effi ciency and economy of electric transmission, the practically unlimited possibility of subdivision in distribution, and the efficiency and simplicity of conversion of electric energy into any other form of energy, from the small lamp of a few watts power consumption, to the huge motor of many thousand horse power. In the pro duction of light from electric energy at present the efficiency is low, due to the use of heat as intermediary form of energy. A direct con version of electric energy into light giving an efficiency of 50 per cent or more would make electric lighting many times cheaper than any other form of illumination and so displace all other illuminants. In this direction fair promise of a gradual advance exists. The direct con version of the stored energy of coal into electric energy and thereby the elimination of the enor mous loss of energy between the chemical energy of the coal and the electric energy is still en tirely hopeless and no clue to its solution visible. In electro-chemistry (q.v.), that is, the transfor mation of electric into chemical energy, lies an enormous field which has already produced powerful industries, as the aluminum and car bide production, and therefore holds out the hope of most wonderful advances in the future. See ELECTROCHEMICAL INDUSTRIES; METAL LURGY; and various other articles in this volume on electrical subjects.