128 Mi Rudge, On the Electrification given 
manipulating the apparatus and the charges upon the steam and 
the air simultaneously observed. 
Fei 
When the steam was allowed to escape from the boiler, if the 
pressure was more than 150 mm. above that of the atmosphere, 
the steam, and the air also, was found to be strongly charged. An 
insulated conductor placed in the steam showed a positive charge, 
and the radium coated plate, which might be anywhere in the 
room, also indicated a positive charge. If the quantity of steam 
escaping was large the charges sent the gold leaves out at right 
angles to the supporting plates. By moving the radium coated plate 
about the room the charge could be detected in all parts, but the 
maximum effect was found at the centre, even though the boiler 
was at one end. That the air itself was actually charged was 
shown by carrying a large box which had been open in the room for 
some time, outside, and on putting an electroscope with a radium 
coated wire inside the box, a positive charge was found to be 
present. If the electroscope was placed upon the window-sill — 
outside the room no charge was noticed, but on opening the 
window, and opening the door suddenly, a current of air could be 
sent out of the window, and that this carried a charge was at once 
shown by the electroscope, and this was the case some time after 
condensation of the steam. 
In a closed room the charge given to the air by a very small 
quantity of steam will persist for a long time. In one particular 
case the boiler was arranged outside a room measuring about 
5x 4x3 metres, and a jet of steam from an orifice 1 mm. in 
diameter sent into the room for about five minutes. This charged 
the air to such an extent that the gold leaf of the electroscope 
was sent out nearly at right angles, and the charge could be 
detected in the room for more than one hour afterwards. This 
same persistence of the charge after condensation of the steam 
has also been noted on a railway journey. If an electroscope 
having a collector attached is carried in a closed railway carriage, 
no charge is indicated. If the window is opened a charge can be 
detected upon that side of the train from which the steam is being 
carried. On entering a tunnel, a quantity of steam gets carried 
into the carriage, and at once a strong charge can be detected. 
If the window is now shut the charge will remain, notwithstanding 
the condensation of the steam, and may be noted many minutes 
afterwards. 
A set of experiments was made to ascertain whether the 
presence of dissolved matter in the water had any influence on the 
charge given to the air by the steam. In most cases the charge 
was positive. Table I gives a few of the effects obtained. Only 
a few such are given but they are typical of the rest. It may be 
noted that volatile salts may give vegative charges, as also did 
