Intelligence and Miscellaneous Articles. 



367 









EI. 



L 



E. 



I. 







Obs. 



Cal. 



centim. 



volt. 



amp. 







1 



35 



0-9 



32 



32 



2 



39-3 



1-6 



63 



64 



3 



41-5 



2-4 



99 



96 



4 



42-8 



31 



132 



128 



5 



44 



3-7 



163 



160 



6 



44-8 



4-3 



192 



192 



7 



45-5 



4-8 



218 



224 



8 



46 









The quantities of electrical energy expended in the voltameter 

 are virtually proportional to the maximal lengths of the sheath 

 which they can4)roduce. 



The hght which is seen on the electrode is discontinuous ; there 

 are at first only some briUiant orange points at the end of the 

 wire ; then a fringe of a violet colour extends over the whole of 

 the immersed part. 



This pa,rt becomes greatly heated and the heating contributes 

 powerfully to keeping up the .sheath. If in fact the current is 

 broken the sheath does not at once disappear, and a hissing is 

 produced when the liquid touches the metal. In like manner the 

 transition from the sheath to bubbles, when the electrode being 

 gradually immersed reaches a certain depth, is accompanied by 

 a kind of explosion. On the other hand, with a potential lower 

 than 32 volts, the sheath can be produced on the negative wire 

 which has been previously heated ; but the phenomenon is then 

 transitory, and the disengagement in the form of bubbles soon 

 takes place across the liquid which has come in contact with the 

 cooled wire. 



The sheath having beeii formed for a certain length, if the dif- 

 ference of potential between the two electiodes be made to in- 

 crease progressively, the calorific and luminous manifestations 

 increase in intensity. The discharges which illumine the sheath 

 become more numerous and more brisk. The disengagement of 

 gas is accelerated ; the liquid rises round the electrode ; and the 

 sheath increases and becomes detached with evolution of light 

 and explosion in the form of large, compressed bubbles. The 

 immersed part of the electrode becomes red hot and may even 

 melt; with an electromoi:ive force of 80 to 100 volts platinum 

 wire, 1*6 millim. in diameter, immersed to a depth of from 2 cen- 

 tim. to 4 centim., is easily melted, while the part of the same wire 

 which is outside is scarcely hot. 



With a great difference of potential it is difficult to produce, 



