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64 INSTRUMENTS AND APPLIANCES

of which the latter is harder, cuts more rapidly and lasts

longer (Fig. 78). Point, Disk. Made of the same materials

Fig. 73.—Black files.

and of vulcarbo, the Point (Fig. 79) being of vari-
ous shapes, as barrel, cone, bud, bell, etc., and

ranging in several sizes. Also made of Arkansas,
Scotch and Hindoostan stone when intended for
finer grinding, these materials being of a much
smoother grain than carborundum. The ''Gem^^
Point is excellent for finer grinding and for cavity

margins. The Diamond Point and Disk are like-
wise valuable for cutting enamel, separating and
finishing. The Diamond is largely utilized in
this form for drilling cavities in artificial teeth.

Disks (Fig. 81) are also made of paper and cloth,
charged with emery, sand, garnet and cuttle-fish
bone for polishing purposes (Fig. 81). The cuttle-
fish disk is the finest grain of these, and is in-
tended for very fine cutting and polishing. A

variety of disk known as Croats is very A'aluable
for putting an extremely velvety finish to gold
fillings. Disks for carrying polishing powders,
such as pumice, corundum flour, chalk, oxide of