ELECTRICITY 201 1. The Nature of the Current.óCurrents generated at high voltages are dangerous to life. Alternating currents are considered more dangerous than continuous currents, probably because they are usually generated at high tensions; but continuous currents of high tensions are equally dangerous under similar circumstances. Bettelli9 considers that alternating currents of low periodicity are dangerous even at low voltages, but the danger diminishes with the increase of frequency even when generated at high voltages. In addition to high voltage, long duration and close contact are the f essential features of danger from electric currents. * In continuous currents shock is produced at the moment of the opening and closing of the circuit. In alternating currents it is also produced at each reversal of the machine. Many of the fatal accidents have occurred from currents carrying more than 1,000 volts, but cases are recorded, where death has resulted from currents of 200 or even lower volts. In such cases the victims were mostly standing in water or on damp ground^ and were thus well " earthed ". Professor Jellinek mentions the case of a man who was killed by a cur- rent of 95 volts, when standing with wet boots in a mixture of potash and sugar in a factory at Prague. On the other hand, recovery has occurred after the passage of a current of 2,500 volts and even of 5,500 volts. Fitzsimons30 records the case of a man, through whose body a current of 20,000 volts passed at a colliery. He recovered consciousness after twenty minutes' artificial respiration. He was none the worse after a few days, except for a large piece of flesh which sloughed from the sole of one of his feet. He was standing at the time of the shock on a dry concrete floor, but totally unprotected as regards gloves or rubber shoes. The danger of a person in a bath touching a defective electrical switch in consequence of the water and bath furnishing a perfect " earth " for the current is well known. Fig. 74.óLesion of hand from contact with a live current of 250 volts. (From Pathological Museum, King George Medi- cal College.) A girl, aged 17 years, on going to her bath took an electrical neater with her to warm the bath-room. After a few minutes her mother heard screams and forced the door open. She found the girl unconscious in the bath with the heater on the top of her. She was removed to hospital where she died. A woman, 23 years old, took a book and an electrical hair drier to her bath-room. Her father found her with the drier in her right hand and the book at the end of the bath. When he touched her, he got a shock himself, the handle of the drier being saturated and the current still on,11 Judicial electrocution is the form of execution employed in the United States of America. For this purpose the condemned criminal is seated and strapped in a strong chair, and an alternating current of 7J amperes at a pressure of 1,700 to 2,000 volts is, as a rule, passed three times for about thirty seconds through the body by means of metal electrodes placed over the head and round one leg. 9. Lewis Jones, Medical Electricity, Ed. TH, p. 315. 10. Brit Med. Jour., Nov. 15, 1924, p. 932. 11. London Correspondent, Jour. Amer. Med. Assoc., March 11, 1933, p. 752.