Marcu 18, 1897 ] 
NATURE 
473 
diselectrified it in about five seconds; not, however, to the | 
metallic zero of the electrometer, but to a “ rays-zero’’ depend- 
ing on the nature of the insulated metal and of the metal sur- : 
rounding it. 
With paraffin between the aluminium ¢ylinder and the 
insulated metal within, as shown in the diagram, the following 
results were obtained :— 
December 30, 1866. 5.30 p.m.—Interior metal charged 
negatively. Total charge 356. 
Rontgen lamp in action 
and no screen... -.. 39 scale divisions discharged in 5 mins. 
R. L. not acting... ... 25 Pr 35 Re. 
R. L. again acting and ; 
no screen ... > 1¥f 4 aan 
5.45.—Interior metal charged positively, Total charge 244. 
R. L. in action and lead 
screen .., «.. «.. I scale division discharged in 3 mins. 
Rk. L. in action and no 
Screech’ —aaaeeeees. 0 ” 7 > 
sa Ge 
R. L. not acting... ... 0 ; 
Dec. 31, 1896. 10.54 a.mn.—Interior metal charged positively. 
Total charge 163. 
R. L. not acting... 2 scale divisions discharged in 3 mins. 
k. L. acting &no screen 1 ai ee 8 
11.0—R. L. stopped... 1°5 cp =) 2 
R. L. again acting, no 
SCEEEN! | seueee= 3 . "a 
RL. stoppedauereneecme 2:5 x a 
11.12.—Interior metal charged negatively. Total charge 342. 
R. L, not acting... ... 10 scale divisions discharged in 3 mins. 
oF 
R. L. acting, no screen 21 p oe 3 
11.18—R. L. stopped 11°5 » + Bie G5 
R. L, acting, no screen 16°5 5 » 2) 0 
R.L. 
Fic. 1.—a. T., Aluminium tube ; L. r 
L.s., Lead sheaths; E., Electrometer ; 
Lead tube; R. L., Réntgen lamp ; 
., Paraffin ; z.c., Zine cylinder. 
These results are quite in accordance with those found in 
similar experiments by Rontgen ; and they show that if paraffin 
is made conductive, it is only to so small an extent that it is 
scarcely perceptible by the method we have used. 
To make a similar series of experiments with glass, we used 
a piece of glass tubing 9°5 mm. thick, length 70 cm., and 1 cm. 
external diameter. The inside of this tube was coated with a 
deposit of silver, which was placed in metallic connection with 
the insulated terminal of the electrometer. The outside of the 
glass was covered with wet blotting-paper connected to sheaths. 
With this arrangement we obtained the following results :— 
Feb. 8, 1897. 
Insulated terminal of electrometer charged to — 333 scale 
divisions from the metallic zero. 
4-23.—R6ntgenlamp, acting ..._ 0°5 sc. div. lost in 3 mins. 
», Nhotacting... 1°0 ” : 5 » 
3 3 
Charged to + 164 scale divisions from the metallic zero. 
4.36.—Rontgen lamp, not acting ... 13 sc. divs. lost in 7 mins. 
Ph » acting 85 Py) ap OS) 3 
REECObacting... 6:0 45°) 9my 816), 
” or acting he 35 ” 72 es) 
not acting... 3°5 » 5» 
3) td pha ”? 
(Sensibility of electrometer, 140 scale divisions per volt. ] 
We next removed a part of the wet blotting-paper from the 
outside of the glass, and, after having charged the insulated in- 
terior metal deposited on the inside of the glass, we heated the 
exposed part with a spirit flame, in this way making the glass 
a conductor. Thus witha charge of + 280 scale divisions from 
NO. 1429, VOL. 55 | 
| 
| coated throughout half their lengths with tinfoil. 
the metallic zero, the loss in 30 seconds, during which time the 
glass was heated in the spirit flame, was go scale divisions ; in the 
next minute, with no further heating, the loss was 20 scale 
divisions. Re-application of heat gave complete discharge: 
| in 23 minutes. Thus we see that our method is amply sensitive 
to the conductance produced in glass by heating. 
We conclude that the Réntgen rays do not produce any con- 
| ductance perceptible in the mode of experimenting which we 
have hitherto followed. 
A similarity in effects produced by flame and by Réntgem 
rays is brought out by the following experiments. 
Two similar sticks of paraffin, which we shall call A and B 
respectively, each of about four sq. cm. cross section, were 
These tinfoils 
ought to be each metallically connected to sheaths. 
To obtain a sufficiently delicate test for their electric state, a 
metal disc of three cm. diameter was fixed horizontally to the 
insulated 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-tin- 
foiled 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 ot 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, in- 
duced 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 
position were passed through the flame. Théy were tested with 
their ends still pressed together, and it was found that when held 
as near as possible to the metal disc without touching it, no read- 
ing was produced on the electrometer. After this they were 
separated and tested separately ; and it was found that B, when 
held over the disc, gave a large reading in the same direction as 
before it had been passed through the flame, and A (which was 
previously non-electrified) gave a reading of about the same 
amount in the opposite direction. 
The same results were obtained when Rontgen rays were 
substituted for the flame. 
The explanation clearly is this : the flame or the Rontgen rays 
put the outer paraffin surfaces of A and B temporarily in con- 
ductive communication with the tinfoils; but left the end of B, 
pressed as it was against the end of A, with its charge undis- 
turbed. This charge induced an equal quantity of the opposite 
electricity on the outer surfaces of the paraffin of A and B 
between the tinfoils ; half on A, half on B. 
When the application of flame or rays was stopped, this 
electrification of the outer paraffin surfaces became fixed. B, 
presented to the electrometer, showed the effect of the charge 
initially given to its end, and an induced opposite charge of half 
its amount on the sides between the end and the tinfoil. A 
showed on the electrometer only the effect of its half of the 
whole opposite charge induced on the sides by the charge on. 
B’s end. 
We have here another proof that paraffin is not rendered, 
largely conductive by the Rontgen rays. Had it been made so, 
then the charge given to the end would have leaked through the 
body of the paraffin to the outside, and have been carried away 
either by the tinfoil or by the conductive air surrounding the 
non-tinfoiled parts. ! 
To show that the induced charges were fixed on the sides, the 
two sticks, A and B. were next coated with tinfoil throughout 
their whole length, only one end of each being uncovered. 
The uncoated end of B was then charged and pressed against 
that of A, and the two were held either in the flame of a spirit- 
lamp or in the Réntgen rays. When taken out of the flame or 
the Réntgen rays, and then separated and tested separately, it 
was found that B had retained its charge practically un- 
diminished, and that A had acquired a very slight charge of 
the opposite kind. 
