288 Scientific Proceedings, Royal Dublin Society. 
my friend, Professor M‘Leod, he informs me that, after hearing of 
my experiments, he tried to get rid of the induced currents by 
another plan, and met with some success. Professor M‘Leod 
writes -— 
“A cell of dilute sulphuric acid allows currents of high potential 
to flow through, but stops those of low, so I thought a cell used as 
a shunt would take off to earth all the induced currents on the 
line, allowing some, at least, of the magneto-electric currents to 
pass to the Telephone. I tried it on a short line, using, at first, 
a beaker, containing sulphuric acid and water, in the proportion 
of about one to twenty, and two platinum plates of Grove’s bat- 
tery ; this entirely removed the induced currents, and also the 
Telephone currents. By making the acid very dilute, and using 
wires instead of plates, a regulation could be obtained by dipping 
the wires to different distances in the liquid when the induced 
currents were entirely removed ; the voice was still audible, but 
only feebly.” 
