Brush Discliar ge in Water and Salt Solutions. 463 



wire was suspended in it to act as an electrode (fig. 2). In 

 this case no visible discharge occurred at either electrode, 

 but the capillary, if sufficiently fine, was rendered luminous 

 by a high tension current. The volume of all the cells used 

 in these experiments was 200 c.c. 



Fkr. 1. 



Fiff. 2. 



f-lf. TINUM Pl/)T£- 



PLflTlHUM- 

 PLAT£ 



> W/ffE 



ELECT.fOOE 



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In the case of distilled water and weak solutions it was 

 possible to obtain a luminous discharge in either form of cell 

 simply by connecting the electrodes to the secondary of the 

 induction-coil. If the points protruded, or were too broad, 

 or if the capillary was too wide, or the solution too strong, 

 no luminous discharge occurred. 



The introduction of a spark-gap in series with the cell 

 had no noticeable effect. The insertion of a condenser in 

 parallel with the cell increased the luminosity in weak 

 solutions and acids. If a spark-gap was now put in series 

 with the cell the discharge increased in luminosity and 

 violence. In this type of discharge the width of the point 

 or capillary was of little importance. Even a protruding 

 point yielded a brush with the condenser and spark-gap 

 discharge ; the brush in this case conGned itself chiefly to 

 the extreme end of the wire, although it occasional! v 

 appeared at the junction of the platinum and the glass. In 

 distilled water and very weak solutions the condensed brush 

 was always feeble. It was brightest and most violent in 

 fairly strong solutions. 



A mirror, rotated by hand, was used to observe chances 

 occurring in the brush or capillary discharge. When no 

 condenser or spark-gap was used it showed the discharge 

 drawn out into long bands of light, separated by short dark 

 spaces. Each band corresponded to one-half alternation of 

 the current, the dark spaces occurring when the current in 

 the primary had reached its maximum or minimum value. 

 The introduction of a condenser broke each of these bands 

 up into a series of dots — generally about twenty. The 



