400 
Proceedings of Boyal Society of Edinburgh. 
SESS, 
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 per- 
ceptible by the method we have used. 
§ 9. To make a similar series of experiments with glass, we used 
a piece of glass tubing 9*5 mm. in diameter, length 70 c.m., and 
1 c.m. external diameter. The inside of this tube was coated with 
Diagram 2. — A.T, Aluminium tube ; L.T, Lead tube ; R.L, Rontgen lamp ; 
L.S, Lead sheaths ; E, Electrometer ; P, Paraffin ; Z.C, Zinc cylinder. 
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 
o 
divisions from the metallic zero. 
4.23. — Rontgen lamp, acting, . . . 0*5 sc. div. lost in 3 mins, 
,, ,, not acting, . . . TO ,, „ 5 ,, 
Charge to + 164 scale divisions from the metallic zero. 
4.36. — Rontgen lamp, not acting, 
„ ,, acting, 
,, ,, not acting, 
,, „ acting, 
,, ,, not acting, 
. 13 sc. div. lost in 7 mins. 
. 8*5 
3 3 
33 
5 
3 3 
. 6'0 
33 
33 
6 
3 3 
. 3-5 
3 3 
3 3 
5 
3 3 
. 3-5 
33 
3 3 
5 
3 3 
[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 
interior 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 with a charge of + 280 scale divisions from the 
