it is cleaned before beating not having been thoroughly
removed. Foil held under the surface of distilled water and boiled for
five minutes, then left until the water is cold, removed and dried,
shows it has been annealed, which makes it work easily, but not as hard
a filling can be made from it as before boiling.

In selecting and using this material for filling, we are able fully to
protect the cavity; and if we understand the material, and how to
manipulate it, we will surely succeed. This statement demands serious
attention, and appeals to every one who is anxious to practice for the
best interests of his patients; then let us make a thorough study of the
merits of the method and material.

Until recently, the term cohesion had but one special meaning to
dentists, and that as applied to gold for filling teeth; being
understood as the property by which layers of this metal could be united
without force so as to be inseparable. The writer claims that good tin
foil in proper condition is cohesive when force is applied, and can be
used for filling teeth in the same manner in which cohesive gold foil is
used. This claim has been confirmed by several dentists, as noted in
another part of this volume.

Cohesion is the power to resist separation, and it acts at insensible
distances. The integral particles of a body are held together by
cohesion, the constituent parts are united by affinity.

The attraction between atoms of pure tin represents cohesion. Marble is
composed of lime and carbonic acid, which are united and held together
by affinity.

The condition which obtains in the tin may be called cohesion, adhesion,
welding, or interdigitation, but the fact remains that layers of tin
foil can be driven together into a solid mass, making a tight filling
with less malleting than is required for gold; if it is overmalleted,
the receiving surface is injured.

On account of its pliability it is easily adapted to the walls and
margins, and a perfect fit is made, thus preventing capillary action and
preventing further caries. Of all the metals used for filling it is the
best tooth-preserver and the most compatible with tooth-substance, and
the facility with which a saving filling can be made largely commends
it.

Tin has great possibilities, and has already gained a high position as a
filling-material. Upon the knowledge we possess of the possibilities and
limitations of tin as a filling-material, and our ability to appl