the motor has stopped, there is generally enough carbide remaining in the
feeding disc that can be shaken off, and fed by running the motor to
obtain some pressure in the generator. The desirability of discharging
the residuum with some gas pressure is because the pressure facilitates
the discharge and at the same time keeps the generator full of gas,
preventing air mixture to a great extent. As soon as the pressure is
relieved by the withdrawal of the residuum, the vent valve should be
opened, as if the pressure is maintained until all of the residuum is
discharged gas would escape through the discharge valve.

Having opened the vent pipe valve and relieved the pressure, open the
valve in the water filling tube. Close the residuum valve, then run in
several gallons of water and revolve the agitator, after which draw out the
remaining residuum; then again close the residuum valve and pour in water
until it discharges from the overflow pipe of the drainage chamber. It is
desirable in filling the generator to pour the water in rapidly enough to
keep the filling pipe full of water, so that air will not pass in at the
same time.

After the generator is cleaned and filled with water, fill with carbide and
proceed in the same manner as when first charging.

_Carbide Feed Mechanism._--Any form of carbide to water machine should
be so designed that the carbide never falls directly from its holder into
the water, but so that it must take a more or less circuitous path. This
should be true, no matter what position the mechanism is in. One of the
commonest types of forced feed machine carries the carbide in a hopper with
slanting sides, this hopper having a large opening in the bottom through
which the carbide passes to a revolving circular plate. As the pieces of
carbide work out toward the edge of the plate under the influence of the