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INTRODUCTION OF THE GOLD. 279

It is not definitely known when packing gokl by percussion W'as first
suggested, but the idea is quite generally accorded to Dr. E. Merrit of
Pittsburg, who as early as 1838 used the hand mallet for condensing
the surface of fillings which had been introduced by hand pressure.
The first mallets used were of light weight and were made of w^ood or
ivory. As the method became more general, heavier mallets were em-
ployed, and those made of lead, tin, various alloys, and steel found much
favor. Before the introduction of rubber dam for excluding moisture
one hand of the operator was employed in holding the napkin, and it
became necessarv to have an assistant at hand to do the malleting:.
This led ingenious minds to discover some means of percussion besides
the hand mallet, and several spring instruments known as automatic
pluggers were introduced. The Snow and Lewis, the Foote, and the
Salmon found greatest favor, and all of them were good of their kind.
The accompanying cut (Fig. 229) shows the Snow and I^icwis Automatic
Mallet as made at the present time. When pressure is applied to the
point of the instrument a spring is liberated wdiich throws a plunger
forward with great force, which is expended upon the gold beneath the
point. The impacting quality of this blow is not excelled by any of
the mechanical devices in use. It is so constructed that a light or a
heavy blow can be given at will. The operator will do well to adjust
the instrument for light blows when using it in close proximity to frail
or delicate walls, as there is more or less danger of fracturing them.
Instruments of this class are not well adapted to packing gold in
the posterior teeth of the lower jaw, as the blow is delivered at a more
or less acute angle, and unless care be exercised when the operation is
nearing completion the plugger point will slip from the surface of the
filling and wound the soft tissues.
Another instrument of this type devised by Dr. Frank Abbott (see
Fig. 230) has a socket at either end of the hand-piece, the one giving a
pushing and the other a pulling blow. The latter is serviceable for
condensing gold upon distal surfaces.
The ELECTRIC MALLET is One of the most ingenious devices em-
ployed in dentistry. The first practical application of electro-magnetic
force for dental malleting was made by the late Dr. AV. G. A. Bonwill.
Its latest development is shown in Fig. 231. This instrument has
found great favor among dentists for packing cohesive gold. Its blows
are delivered with great rapidity and with such force that great solidity
is attainable. A pair of electro-magnets transforms the electric current
into electro-magnetic force, which is transmitted to the hammer. The
electric current is furnished by a Buusen or Partz battery, or the con-
trolled current from a dynamo or storage battery can be used as the
motive power. In the hands of a skilful operator there could be nothing