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square inches. In this case the shocks received were so severe 

 as to render it impossible to bear a succession of them with 

 impunity. Respecting the origin of the current in this case 

 there was some doubt if it was not the induced current, for 

 Faraday had found the needle deflected by the latter separated 

 from the battery. He therefore believed that in all medico- 

 galvanic machines the current was an induced one of intensity 

 and not a quantity current from the battery. Were it the 

 latter, he supposed it might be at the risk of the patient's 

 life, for decomposition of the fluids of the body would take 

 place ; seeing that in the cells of a battery in series, quantity 

 cannot pass through a saline solution without overcoming its 

 chemical attraction. The skin being a feeble conductor of 

 electricity was enabled to reject quantity electricity, while an 

 intensity current overcame the resistance and effected a passage. 

 The experiments of Smee establish this opinion. He farther 

 observed, that if the possibility of a small quantity current 

 passing is granted, it does not follow that it is the battery 

 current, for a quantity current may be as easily induced as one 

 of intensity, and the one from the other ; he referred to the 

 experiments of Henry. He concluded this part of the subject 

 by describing an improved form of apparatus. It consists 

 of a single pair of plates, with a double cell, one of which is 

 charged with the acid mixture, and the other empty; the 

 object of the latter being to receive the plates when not in use. 

 The coil is a compromise between the primary and secondary 

 apparatus ; two wires are employed, one larger than the 

 other, but not disunited, and means adopted for regulating the 

 shock, by diminishing at pleasure the length of the wire to be 

 traversed by the electricity. In this case as in the primary 

 coil, the current obtained in breaking contact was uniformly 

 in one direction, the cross current being cut off by the spring, 

 while the difference in the size of the wires contributed great 

 additional power to the apparatus. 



He then described the usual forms of magneto-electric 



