SECT. ii. O.V STRATIFIED DISCHARGES. 83 



nevertheless certain phenomena gave reason to doubt 

 its continuity. Mr. Gassiot has proved that the tension 

 of a single cell of a galvanic battery increases in force 

 according to the chemical energy of the exciting liquid, 

 and in all his experiments he found that 'the higher the 

 chemical affinities of the elements used, the greater was 

 the development of evidence of tension.' These obser- 

 vations induced him to institute a series of experiments 

 with galvanic batteries of different chemical affinities, 

 and to compare the resulting phenomena with those 

 produced by the induction coil, whose sparks are of high 

 tension. The same carbonic acid vacuum tubes were 

 made use of in all the experiments ; a copper wire 

 formed the positive terminal, and a copper plate was 

 fixed at the extremity of the negative terminal. In 

 other tubes platinum terminals extended into the interior, 

 coated with glass, except the points, to which charcoal 

 balls were fixed. One end of the tubes was of small 

 diameter and contained caustic potash. 



When a discharge from an induction coil was sent 

 through these tubes, there were either minute luminous 

 spots, narrow stratifications, or a well defined cloud-like 

 discharge at the positive pole, according to the size and 

 structure of the terminal, but the characteristic pheno- 

 menon in all the tubes was a large cloud-like luminosity 

 or circular glow on the brass plate or charcoal ball at 

 the negative terminal. 



With 512 insulated cells of copper and zinc of Daniell's 

 constant battery, the exciting liquid being dilute sul- 

 phuric acid, a brilliant glow appeared round the char- 

 coal ball of the negative terminal on the passage of the 

 electric discharge through the tube, with very trifling 

 luminosity of the positive pole. 



Two copper plates that could be separated or closed 

 by a screw; were placed between the poles of a nitric 

 acid battery, so that the circuit could be made or 



