406 



SCIENCE. 



[N. S. Vol. XXIV. No. 613. 



preventing the rapid destruction of condenser 

 tubes and parts, an effort was made to find 

 out if the condenser engineers of the country- 

 did not have suitable information as to the 

 nature of the action tending to destroy the 

 thin tubes and preventing tightness in the 

 condenser, or had not made trials to indicate 

 effective methods of protection. The most 

 competent opinion that we could get was that 

 if we could adjust the difference of potential 

 due to stray ground traction or other currents 

 to a value of less than three volts, we 

 should have no diiBculties; that the troiible 

 was all due to stray ground currents from 

 electric railways and that stray currents from 

 lighting plants had little or nothing to do 

 with the corrosion. They further stated that 

 all that was necessary was to insulate from 

 the possible inflow into the condenser of stray 

 currents from traction operations. It had 

 been found that these currents were already 

 destroying the city water pipes of the vicinity 

 along which they were traveling and to which 

 connection would have to be made. 



With a view to discovering a method of 

 protection, we carefully investigated this state- 

 ment based on the action of a device at the 

 Brooklyn Edison Company's Bayridge Plant 

 caring for this condition, and found it had 

 been an abject failure, ending in the abandon- 

 ment of surface condensers, and the installa- 

 tion of elevated jet condensers at considerable 

 expense, and consequent wasting of the water 

 of condensation. Numerous other instances, 

 more or less efficiently handled, were found. 

 Some of the condensers in other steam plants 

 were so designed and the connections so made 

 that it was absolutely essential to permit the 

 sea-water from the main spaces to pass into 

 the steam space of the condensers by the ac- 

 tual removal of tubes, thereby preventing the 

 re-use of feed water from the hot wells, even 

 if they had been tight otherwise. 



It became evident at once that there was 

 really nothing accurately known about the 

 destructive actions that were taking place in 

 condensers and that a systematic study of the 

 situation for Long Island City was demanded 

 before we should decide on the type of con- 



denser and the wisdom of trying to use hot- 

 well water in the boilers. 



To that end, we measured the stray currents 

 and we found that the voltage of the railroad 

 rails in the terminal freight yard of the Long 

 Island Eailroad at points between the power 

 house and the river was at times as much as 

 nine volts above the potential of the river; 

 that this caused a flow of current to the har- 

 bor and a destruction of water pipes and other 

 things in the railroad yards, and that any- 

 thing that was done would have to be not only 

 able to compensate for this nine volts but 

 must further provide for the control to 

 fit modifications thereof in such a way as 

 to prevent reverse current actions and corro- 

 sion of other things. In other words, with the 

 peak of the load on the Brooklyn Rapid 

 Transit, the voltage would go to nine volts ; 

 and as the load sagged off it would decrease, 

 until it was only a volt or two. Therefore, 

 whatever was put in must be thoroughly con- 

 trollable from time to time by switchboard 

 appliances. 



In order to properly study the real condi- 

 tions a number of large glass jars were pro- 

 vided and various combinations of metals were 

 immersed in samples of water taken from the 

 river at Long Island City, of sea water from 

 off Far Kockaway, as well as of pure water. 



It became evident that the effect of samples 

 of water from the East River was much more 

 violent than that of ordinary sea water. It was 

 further observed that there was a local action 

 going on which was galvanic, and that the 

 amount of stray currents had something to do 

 with the polarization of the surfaces in gal- 

 vanic action, making the galvanic action ex- 

 ceedingly violent and destroying thin copper 

 tubes at a very rapid rate. There would be 

 punctures of these tubes in four or five days' 

 time which would be fatal to the commercial 

 requirements, producing a very serious repair 

 item in order to maintain the condensers 

 sufficiently to permit their being used to re- 

 turn the reclaimed or hot-well water to the 

 boilers. 



In other words, it would render it impossible 

 to keep them in a suitable condition, as the 



