_Water to Carbide Generators._--It is, of course, much easier to
obtain a measured and regular flow of water than to obtain such a flow of
any solid substance, especially when the solid substance is in the form of
lumps, as is carbide This fact led to the use of a great many water-feed
generators for all classes of work, and this type is still in common use
for the small portable machines, such, for instance, as those used on motor
cars for the lamps. The water-feed machine is not, however, favored for
welding plants, as is the carbide feed, in spite of the greater
difficulties attending the handling of the solid material.

A water-feed generator is made up of the gas producing part and a holder
for the acetylene after it is made. The carbide is held in a tray formed of
a number of small compartments so that the charge in each compartment is
nearly equal to that in each of the others. The water is allowed to flow
into one of these compartments in a volume sufficient to produce the
desired amount of gas and the carbide is completely used from this one
division. The water then floods the first compartment and finally overflows
into the next one, where the same process is repeated. After using the
carbide in this division, it is flooded in turn and the water passing on to
those next in order, uses the entire charge of the whole tray.

These generators are charged with the larger sizes of carbide and are
easily taken care of. The residue is removed in the tray and emptied,
making the generator ready for a fresh supply of carbide.

_Carbide to Water Generators._--This type also is made up of two
principal parts, the generating chamber and a gas holder, the holder being
part of the generating chamber or a separate device. The generator (Figure
10) contains a hopper to receive the charge of carbide and is fitted with