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‘152° © Contributions to Electricity and Magnetism. 
a. 3 é . ” t. 5 
» the shock increased by spreading a stratum of oil over the str- , 
face of the mercury; in this case it is probable that the termina- A , 
¥ 
. tion of the current is more sudden, on account of the preven- 
Laer tion of the combustion of the metal by means of the oil, and the — 
oe fact that the end of the conductor is drawn up into a non-con- 
t, _ducting medium. 
oe 91. The time of the subsidence of the current, when the cir- 
cuit is broken by means of a surface of mercury, is very small, 
-and probably does ‘not exceed the ten thousandth part of a sec- 
ond, but even this is an appreciable duration, since I find that the 
_ Spark at the ending presents the appearance of a band of light of 
considerable length, when viewed in a mirror revolving at the 
rate of six hundred times ina second ; and I think the variations 
in the time of ending of the current under different conditions 
may be detected by means of this instrument. 4 
92. Before concluding this communication, I should state tha 
I have made a number of attempts to verify the suggestion given 
in my last paper, (III, 127,) that an inverse induction is produced 
by a galvanic current by a change in the distance of the conduc- 
tors, but without success. These attempts were made before I 
had adopted the views given in this section, and since then! 
have found (80) a more simple explanation of the alternation of 
the currents. 
93. In this number of my contributions, the phenomena ex- 
hibited by the galvanic apparatus have alone been discussed. 
have, however, made a series of experiments on the induction 
from ordinary electricity, and the reaction of soft iron on currents, 
and I think that the results of these can also be referred to the 
simple principles adopted in this paper; but they require further 
examination before being submitted to the public. 
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