ELECTROLYSIS OF GAS AND WATER MAINS (from Gk. 1NKrpop. efektron. amber lysis, discu1olion, Horn No ELF, lytin, to loosen. The eating away or disintegrating of the metal. caused by stray elect riea 1 currents. Elect tie st•eet-railway systems are chiefly responsible for this action, through the lack of proper facilities for the return currents from the car motors to the power-house. The softening or pitting of the pipes takes place where the current leaves them. particularly at joints, where the electric-al re sistance of the metal is greater than that of the surrounding earth. The danger from this source was so little realized in the early days of electric street railways that direct electrical connection was sometimes made with gas or water mains. Since about 1892 the problem has been assuming more and more serious proportions. and there have been numerous papers and on this subject at the meetings of the various water works and gas association-. At the points of de parture of these stray currents. whether perma nent or temporary, the metal., be it iron, steel. or lead, is liable to become so badly decomposed as to be in serious danger of giving way. This is particularly true of water-mains, which are under very many times as much pressure as gas mains. When water-mains are thus broken great damage may be done by the escaping water, and a city or portion of a city might he at the mercy of the !lames if a fire should break out. If, instead of the mains, the service-pipes or house connections give way, the danger and in convenience are not so great. hut no end of trouble and much needless expense are often caused.
Where gas-mains fail. the ground becomes more or less permeated with gas. and if the latter has an opportunity to accumulate. an explosion may occur. Since IS90 water-works managers have had more and more trouble with electroly-is.and in several instances have felt compelled to sue street-railway corporations for damages and to ask the courts to enjoin the trolley companies from at continuance of the conditions which give rise to so much anxiety. expense. and danger. Up to 1901 none Of these -suits had been decided by the higher courts, lint preliminary rulings had. in a few instances, been made in favor of the water and gas work-. It should lie under stood that the rails of the trolley lines are in jured where the current leave, them. and that these imperfection, in the circuit increase the power required to operate the railways. The remedy for the evil is to provide ample and un failing means for the return of the current to the power-house. :Mita can he eiri.cled, in the case of the ordinary single-wire overhead trolley. by a thorough bonding of the rails: but the con sensus of opinion among water-works officials is that this is insuflicient or unreliable, and that either the double overhead-trolley system or an underground return wire huuld 1)0 provided. Consult the Journal of the cle England Water Works Association, and the Proect.ilings of the m•rican Water-Works .Issociation for profes sional and technical papers on this subject.