132 Mr Rudge, On the Electrification given 
dry steam cylinder is also apparently. positive but not very strongly | 
so. A small insulated-ring shaped electrode was arranged to 
surround the jet at less than lem. from the orifice. The ring 
could be moved so as to cut through the jet of steam, and an 
electroscope joined to it indicated the charge acquired by the ring 
in different positions. Fig. 3 shows the charges obtained in 
different positions (a), (b), (c). No charge was indicated when: 
the ring was at (a), a positive charge when the ring just grazed 
the outside of the steam jet, and a strong negative one when the: 
wire was at the centre of the jet. It must be remarked that the‘ 
presence of the wire in the jet rather disturbs it, and of course a: 
part of the wire is passing through the outer positive layer, but the ‘ 
negative charge in the central part of the steam column is evidently | 
much greater than the positive charge on the outer portions. 
The experiments were repeated in the Engineering Laboratory | 
at Cambridge, using much larger volumes of steam and much 
; 
+ 
Fig. 3. When the wire ring is in the position shown at A no charge is indicated 
by the electroscope, at B a positive charge is shown and at C a negative one. 
higher pressures than could be obtained with the small boiler, but, 
save in the magnitude of the charges obtained, the general results 
were the same. Pressures up to eight atmospheres were used and 
jets varying from 1 mm. up to 8 mm. diameter were employed. 
The charge given to the exploring electrode was the same as with 
the smaller boiler, but the inversion point was much farther away 
from the orifice, in one case nearly 5 cms. The air of the boiler 
house was very strongly charged with positive electricity. 
When a clean needle electrode was placed in the current of 
steam it was observed that the steam condensed upon the point in 
the form of small drops which quickly coalesced into one large one. 
This large drop was fairly permanent when it had reached a certain 
size and the rate of growth and evaporation balanced. It then 
clung tenaciously to the needle, and when the charge shown by 
