GENERAL METHODS OF INVESTIGATION, BY S. STRICKER. XXI 



copper supports K, which were attached to the stage p. The 

 electrodes were fastened to the supports, and the object was 

 brought between the points of the 

 lamina of tin-foil. The mode al- 

 ready described of obtaining and 

 transmitting a current for the pur- 

 pose of observing the effects of heat, 

 will also, of course, serve for observ- 

 ing those of electricity. When this 

 is the object in view, the slide should 

 only be covered on its surface with 

 tin-foil, in the form represented in 

 fig. x. The springs resting on 

 ebonite rods will serve as conduct- 

 ors. The distance of the laminae of 

 tin-foil from one another is of im- 

 portance in regard to the trans- 

 mission of the current. As a general 

 rule they should not be separated 

 from one another to a greater ex- 

 tent than a few millimeters. I pre- 

 fer to see the two electrodes at the 

 sides of the field, because then the 

 position of the object in regard to 

 them, and to the middle line, is 

 simultaneously visible. It is a 

 matter of very great moment to 

 observe and distinguish between 

 the effects of the current in the 

 immediate neighbourhood of the 

 poles, and at some distance from 

 them ; for the effects of electrolysis 

 are produced on breaking the cur- 

 rent in the vicinity of the elec- 

 trodes, and the tissues become al- 

 tered as they would be were they 

 subjected to the action of weak 

 acids or alkalies. 



At parts more remote from the electrodes changes also occur, 



