1896 - 97 .] Apparent and Real D ^electrification . 401 
metallic zero, tlie loss in 30 seconds, during which time the glass 
was heated in the spirit flame, was 90 scale divisions ; in the next 
minute, with no further heating, the loss was 20 scale divisions. 
Reapplication of heat gave complete discharge in 2| minutes. 
Thus we see that our method is amply sensitive to the conduct- 
ance produced in glass by heating. 
We conclude that the Rontgen rays do not produce any con- 
ductance perceptible in the mode of experimenting which we have 
hitherto followed. 
§ 10. A similarity in effects produced by flame and by Rontgen 
rays is brought out by the following experiments. 
Two similar sticks of paraffin, which we shall call A and B 
respectively, each of about 4 sq. cm. cross section, were coated 
throughout half their lengths with tinfoil. These tinfoils ought 
to be each metallically connected to sheaths. 
To obtain a sufficiently delicate test for their electric state, a 
metal disc of 3 cm. diameter was fixed horizontally to the insu- 
lated terminal of the electrometer. 
The two pieces of paraffin were first diselectrified by being held 
separately in the flame of a spirit-lamp. Their non-tinfoiled ends 
were then pressed together, and their electric state again tested 
after separation. It was found that they were still free from 
electric charge. After this B was charged by being held over the 
pointed electrode of an inductive electric machine. The quantity 
of electricity given to it in this way was roughly measured by 
noting the electrometer reading when the paraffin was held at a 
distance of 4 cm. above the metal disc connected to the insulated 
terminal of the electrometer. 
The free ends of A and B were again held together, and, after 
separation, both pieces were tested separately. The charged one, 
B, had suffered no appreciable loss, and the other, A, induced an 
electrometer reading of a few scale divisions in the same direction, 
when held as near as possible to the metal disc without touching 
it. This showed that an exceedingly minute quantity of electricity 
had passed from B to A when they were in contact, 
A was then diselectrified by being held alone in the flame. 
The ends of A and B were again put together, and in this posi- 
tion v T ere passed through the flame. They were tested with their 
