which depends upon the direction of the current.


EXPERIMENTS SHOWING THE EFFECTS OF RESISTANCE.

By placing the galvanometer in the circuit of the battery, as shown in
Fig. 9, and noting the deflection of the needle, it will be
ascertained that a certain amount of current is flowing. Now, by
placing in the circuit, in addition to the galvanometer, the remaining
coil of the magnet, thus introducing considerable resistance, the
current will be diminished, as shown by a smaller deflection of the
needle.


RESISTANCE OF A FLUID CHANGED BY THE ADDITION OF ANOTHER FLUID.

A very pretty and instructive experiment may be performed by arranging
the apparatus as shown in Fig. 10, with the copper strips, H H,
inserted in clean water and the galvanometer placed in the circuit.
The deflection of the galvanometer needle will be very slight, showing
that the resistance of clean water is considerable. A few drops of
sulphuric acid or even vinegar will increase the conductivity of the
water so as to produce a marked deflection of the galvanometer needle.

Common salt added to the water will produce the same effect.


MAGNETIC ELECTRIC INDUCTION.

By placing one of the coils, A, on the magnet frame, B, and connecting