126 Prof. J. C. Poggeudorff on the Induction Apparatus 



generated electricity is thereby increased. Hence a pole of the un- 

 connected induction current acts upon the electrometer at a much 

 greater distance when the condenser is employed than when it 

 is not. From this it follows, that when the ends or poles of the 

 induction wire are separated by a certain thickness of air, the 

 sparks which break through it are increased in number when a 

 condenser is employed ; indeed, many sparks appear when this 

 distance between the poles is so great, that, without a condenser, 

 not a single one would be visible. The condenser, therefore, 

 actually increases that part of the electricities which equalize 

 themselves at the poles, or are set in circulation, when the induc- 

 tion wire is interrupted by air. 



This is also proved by the galvanometric deviation, which, 

 under these circumstances, is increased ; whilst, as has before 

 been mentioned, it is not changed by the condenser when the 

 metallic continuity of the wire is unbroken. It is also proved 

 by the decomposition of water which is effected by the induction 

 current when broken by air ; for this action is also increased by 

 the condenser. 



What has here been said of tensions, sparks, deviations, and 

 decompositions, is also true of the physiological actions, — of the 

 shocks which are received when part of the body is introduced 

 into the circuit. These are also increased by the condenser. 

 Not only is the action of the external ov actual induction current 

 more intense, but that of the inner or extra current is also in- 

 creased. I have convinced myself of this in several ways, the 

 least painful of which was the following. Two platinum plates 

 were placed in spring-water, and connected either with the poles 

 of the induction coil or with the hammer on each side of the 

 point of interruption. If the finger be immersed in the water 

 between the plates, the effect of introducing the condenser can 

 be observed without pain. The action is increased with the 

 quantity of the current, as Faraday terms it. With the thin 

 induction wire the action is exceedingly weak, stronger with the 

 thick induction wire, and most sensible with the still thicker 

 wire of the extra current. 



These experiments induce me to believe that for most of, if not 

 for all, the medical applications which are now so frequently made 

 of the apparatus, the induction coil is quite superfluous, for the 

 extra current can easily be made so strong that no patient would 

 be able to bear its effects. 



Certain it is that the action of the condenser is strengthening 

 only when, between the poles, there is a resistance to overcome. 

 The more this resistance is diminished the less the action of the 

 condenser. On this account its action is much stronger with 

 sparks in free air than with the luminous phsenomena in the 



