like manner on the other
conductor; set both wheels a going again, and the same number of
turns that charged it before, will now discharge it; and the same
number repeated, will charge it again.
5. When each globe communicates with the same prime conductor, having
a chain hanging from it to the table, one of them, when in motion
(but which I cannot say) will draw fire up through the cushion, and
discharge it through the chain; the other will draw it up through the
chain, and discharge it through the cushion.
I should be glad if you would send to my house for my sulphur globe,
and the cushion belonging to it, and make the trial; but must caution
you not to use chalk on the cushion, some fine powdered sulphur will
do better. If, as I expect, you should find the globes to charge the
prime conductor differently, I hope you will be able to discover some
method of determining which it is that charges positively.
I am, &c.
TO MR. E. KINNERSLEY, AT BOSTON.
_Probable Cause of the Different Attractions and Repulsions of the
two electrified Globes mentioned in the two preceding Letters._
_Philadelphia, March 2, 1752._
I thank you for the experiments communicated. I sent immediately for
your brimstone globe, in order to make the trials you desired, but
found it wanted centres, which I have not time now to supply; but the
first leisure I will get it fitted for use, try the experiments, and
acquaint you with the result.
In the mean time I suspect, that the different attractions and
repulsions you observed, proceeded rather from the greater or smaller
quantities of the fire you obtained from different bodies, than from
its being of a different _kind_, or having a different _direction_.
I am, &c.
TO MR. E. KINNERSLEY, AT BOSTON.
_Reasons for supposing, that the glass Globe charges positively,
and the Sulphur negatively.--Hint respecting a leather Globe for
Experiments when travelling._
_Philadelphia, March 16, 1752._
Having brought your brimstone globe to work, I tried one of the
experiments you proposed, and was agreeably surprised to find, that
the glass globe being at one end of the conductor, and the sulphur
globe at the other end, both globes in motion, no spark could be
obtained from the conductor, unless when one globe turned slower, or
was not in so good order as the other; and then the spark was only
in proportion to the difference,
_ _He exhibits to our consideration, an invisible, subtile matter, disseminated through all nature in various proportions, equally unobserved, and, whilst all those bodies to which it peculiarly adheres are alike charged with it, inoffensive.Page 4
(This is best done by a vinegar cruet, or some such belly'd bottle).Page 9
--To _C_, standing on the floor, both appear to be electrised: for he having only the middle quantity of electrical fire, receives a spark upon approaching _B_, who has an over quantity; but gives one to _A_, who has an under quantity.Page 10
_ We suppose it was _driven off_, and not brought on thro' that wire; and that the machine and man, _&c.Page 11
But suspend two or more phials on the prime conductor, one hanging to the tail of the other; and a wire from the last to the floor, an equal number of turns of the wheel shall charge them all equally, and every one as much as one alone would have been.Page 14
This quantity, proportioned to the glass, it strongly and obstinately retains, and will have neither more nor less, though it will suffer a change to be made in its parts and situation; _i.Page 15
Then dexterously placing it again between the leaden plates, and compleating a circle between the two surfaces, a violent shock ensued.Page 16
With thin paste or gum-water, fix the border that is cut off on the inside of the glass, pressing it smooth and close; then fill up the vacancy by gilding the glass well with leaf gold or brass.Page 20
Thus spirits must be heated before we can fire them by the electrical spark.Page 29
_I am, Sir, Your much obliged Humble Servant_, B.Page 30
We know that the electrical fluid is _in_ common matter, because we can pump it _out_ by the globe or tube.Page 31
The following experiments, as well as those in my first paper, show this power.Page 41
This looks as if the whole received by the bottle was again discharged from it.Page 46
 If the tube be exhausted of air, a non electric lining in contact with the wire is not necessary; for _in vacuo_, the electrical fire will fly freely from the inner surface, without a non-electric conductor: but air resists its motion; for being itself an electric _per se_, it does not attract it, having already its quantity.Page 47
And this can only be done in glass that is thin; beyond a certain thickness we have yet no power that can make this change.