Page 114 - My FlipBook

110 INSTRUMENTS FOR FILLING.

intended point. Nos. 1 to 6 inclusive, may be formed
by forging, and afterward dressing up with the file.
Nos. 7 to 12 must be formed by the files out of a
bulb left from the forge ; for which purpose different
forms and sizes of files will be required, in order

definitely to shape all the angles and points. In heat-
ing steel, either for forging or tempering, a full red
heat should in no case be exceeded, since a higher de-
gree than this spoils it. After the points are formed,
and made smooth with an emery stick or wheel, they
are to be tempered ; which is a delicate process, re-
quiring much experience and care. The point should
be warmed in a spirit-lamp, and then covered with

soap, to prevent o'xydation and scaling. The instru-
ment is then brought up to a full red heat with a

spirit-lamp, blow-pipe, and charcoal, and suddenly
plunged into a cake of soap or into cold water ; when

it will present a silvery whiteness : the steel in this
condition is extremely hard and friable, it then
should be polished off with an emery stick or oil-
stone, and drawn down to the proper temper. This
tempering is accomplished by placing the edge of the
instrument on a piece of cold polished steel or iron,
and its shaft placed near or in the flame of a small
spirit-lamp, and retaining it there till it changes to a
deep blue color, graduated down to the point in a deep
straw or copper hue. The purpose in holding the