Vapour from electrified Still Surfaces of Liquids. 217 
difference of 1 Daniell between the condenser-plates; and this 
difference increased up to 404 Daniells without affecting the 
result. Throughout the experiments the plate A was con- 
nected with the earth, until it was brought opposite the plate B, 
so as to protect the electrometer from too great deflections ; 
then A was insulated. Any trace of electricity which might 
have been conveyed by means of the vapour would have 
manifested itself in the electrometer. Furthermore, there 
occurred no convection of the electricity either when B 
possessed the room-temperature and A was cooled below it, 
or when both plates were raised equally above the room- 
temperature, in which latter case evaporation without con- 
densation occurs. If the vapour had- conveyed with it the 
electricity from the water-surface, the presence of electricity 
upon A would have been detected in all the above cases. 
(fe) In order to produce evaporation from different liquids, 
an apparatus represented in the accompanying figure was 
To the 
battery. 
constructed. The experiments were conducted as follows. A 
horizontal brass disk, C, of 125 millim. diameter, surrounded 
by a metal box connected with the earth, was put in metallic 
connexion with the plate B of the condenser. The sealing- 
wax supports used for insulating the connecting wire between B 
and C, and at the same time for retaining firmly the disk in 
its proper position, were so far separated from this disk (both 
being wholly outside the metal box) that vapour employed in 
the experiment could have no effect upon the insulation. An 
insulated porcelain dish, containing the liquid to be experi- 
mented upon, was placed on the arm of a retort-stand, so that 
it could be swung either under the disk C or wholly outside 
the metal box. The experiments were made in three series: — 
(1) Liquid as well as conden sing-disk C of the temperature 
of the room, so that neither condensation nor marked evapo- 
ration took place. (2) Liquid 100° C, disk G cooled so that 
copious evaporation and condensation resulted. (3) Liquid 
