ssed air in its power of favouring
induction through it. The two best results as respected the state of the
apparatus for retention of charge, &c., gave, when the air apparatus was
charged first 1.336, and when the glass apparatus was charged first 1.45,
as the specific inductive capacity for glass, both being without
correction. The average of nine results, four with the glass apparatus
first charged, and five with the air apparatus first charged, gave 1.38 as
the power of the glass apparatus; 1.22 and 1.46 being the minimum and
maximum numbers with all the errors of experiment upon them. In all the
experiments the glass apparatus took up its inductive charge instantly, and
lost it as readily (1269.); and during the short time of each experiment,
acquired the peculiar state in a small degree only, so that the influence
of this state, and also of conduction upon the results, must have been
small.

1274. Allowing specific inductive capacity to be proved and active in this
case, and 1.38 as the expression for the glass apparatus, then the specific
inductive capacity of flint glass will be above 1.76, not forgetting that
this expression is for a piece of glass of such thickness as to occupy not
quite two-thirds of the space through which the induction is sustained
(1253. 1273.).

* * * * *

1275. _Sulphur._--The same hemisphere of this substance was used in app.
ii. as was formerly referred to (1242.). The experiments were well made,
i.e. the sulphur itself was free from charge both before and after each
experiment, and no action from the stem appeared (1203. 1232.), so that no
correction was required on that account. The following are the results when
the air apparatus was first charged and divided:

App. i. Air, App. ii. Sulphur.
Balls 280 deg..

0 deg. . . . .
. . . . 0 deg.
438 . . . .
434 . . . .
Charge divided.
. . . . 162
164 . . . .
. . . . 160
162 . . . .
. . . . 0 after discharge.
0 . . . . after discharge.

Here app. i. retained 164 deg., having lost 276 deg. in communicating 162 deg. to app.
ii., and the capacity of the air apparatus is to that of the sulphur
apparatus as 1 to 1.66.

1276. Then the sulphur apparatus was charged first, thus:

. . . . 0 deg.
0 deg. . . . .
. . . . 395
. . . . 388
Charge divided.
237 . . . .