31(5 NEW CLASSES OF GALVANIC CONDUCTOR*. 



II. 



A Memoir on Tzoo new Classes of Galvanic Conductors^ 

 by Mr. Erman. 



(Concluded from p. 249.J 



Sect. II. Of Conductors, that, in establishing a Contact 

 between the Two Poles, insulate the positive Effect, 

 while they continue to propagate the negative Electricity 



Substances that \ HAVE placed in a fifth class those substances, which, 

 act as conduc- ' * 



tors to either applied to either pole separately, act as excellent conduc- 



ffonrS'the' tors ' but whichj inter P° sed between both poles, insulate 



negative, when the positive effect, without discontinuing to be perfect con* 



they are in con- ductors of the negative. A wish to realise all the combi- 

 i unction. . . 



nations possible in closing the galvanic circle, excited me to 



examine a great number of substances, in order to find 

 some one that should come under this description. My at- 

 tempts were long in vain, because the analogies that guided 

 FUme of phos- my research were very imperfect; and I did not discover 

 soap. tne property in question in the flame of phosphorus, before 



I had found it unquestionably, to exist in a solid body. This 

 body is alkaline soap of every kind, provided it be in the 

 highest state of dryness possible: at least I have found no 

 perceptible difference in the electric effects, whether it were 

 composed of vegetable oil or animal fat, converted into 

 soap by pure soda, or soda mixed with potash, and pre- 

 pared for pharmaceutical purposes, or the uses of the arts 

 and domestic economy. All these soaps exhibited the ef- 

 fects I am about to describe, provided the essential condi- 

 tion of their being desiccated as much as possible were 

 fulfilled. 

 Hard soap, per- A prism of hard soap, completely dried, and applied to 

 plied y t» r either eitner of tne P. oIes of a galvanic pile, conducts all the 

 pole, is a con- electricity of that pole into the ground, and produces a 

 maximum of electric intensity at the opposite pole. In this 

 respect there is no difference between the two poles, and the 

 soap acts as the most perfect conductor would do. Of this 

 I convinced myself by measuring with Volta's electrometer 

 the divergence produced at each of the poles by the contact 1 



of 



