Assumption of a Solar Electric Potential. 167 
length might emanate from it that they would be incapable 
of performing any chemical work ! The apparently dark 
nucleus of the sun-spots might then be accounted for thus : — 
The nameless products of combustion, relatively cooled by 
commencing dissociation, returning to the sun, remain trans- 
parent and permit the deeper layers of the sun, too highly 
heated for luminous radiation, to radiate through them. The 
violet colour of the nuclei of the sun-spots would tell in 
favour of this. For attainable temperatures, it is true, the 
law holds good that, besides the rapid undulations of the 
aether corresponding to the higher temperature, the entire 
scale of the slower undulations comes in also ; but whether 
it is or is not different with temperatures so enormously 
higher cannot, at all events, be known. 
It was necessary to enter somewhat more into particulars 
respecting the constitution of the main body of the sun and 
its light- and heat-radiating envelope, in order to get a foun- 
dation for an answer to the question whether, with the present 
extent of our knowledge, the hypothesis of a solar electric 
potential appears admissible. As I have already insisted, 
its conception is only possible if a separation of the two 
electricities goes on at the sun's surface and if one of the 
separated electricities is simultaneously conducted away. As 
flame is a good conductor of electricity, the entire photosphere 
and the penumbra (which probably take part in the process 
of combustion) may be regarded as a conducting mantle 
enveloping the hotter body of the sun. As, further, flames 
have, like points, the property of transmitting electricity to 
their surroundings (here, therefore, to their gaseous com- 
bustion-products), the photosphere must be continually dis- 
charged by a partial outflow of the products of combustion 
into cosmical space. If, therefore, the photosphere were in- 
sulated from the deeper body of the sun not yet included in 
the combustion, the latter, if it should be regarded as a con- 
ductor of electricity, could be charged with electricity by 
friction or chemical processes taking place between the con- 
ducting body of the sun and the photosphere. The question 
whether hot gases are conductors of electricity, even when 
no flames appear in them, has not yet been decided by direct 
experiments. That gases, like all bodies, become conductors 
of electricity when the dielectric polarization of their mole- 
cules has reached its maximum, and that this maximum 
diminishes proportionally with the rarefaction of the gases, 
consequently also with their heating reckoned from absolute 
zero, I have already shown, when describing my ozone- 
apparatus, in the year 1857*. Accordingly conductors are 
* Pogg. Ann. cii. p. 66. 
