d be thoroughly heated before tools are heated. Hard coal
may be used very successfully in place of hard coke and will give
a higher heat. It is very easy to give Blue Chip the proper heat
if care is used in making up the fire.

FORGING.--Heat slowly and uniformly to a good forging heat. Do
not hammer the steel after it cools below a bright red. Avoid as
much as possible heating the body of the tool, so as to retain
the natural toughness in the neck of the tool.

HARDENING.--Heat the point of the tool to an extreme white heat
(about 2,200 deg.F.) until the flux runs. This heat should be the highest
possible short of melting the point. Care should be taken to confine
the heat as near to the point as possible so as to leave the annealing
and consequent toughness in the neck of the tool and where the tool
is held in the tool post.

COOL in an air blast, the open air or in oil, depending upon the
tools or the work they are to do.

For roughing tools temper need not be drawn except for work where
the edge tends to crumble on account of being too hard.

For finishing tools draw the temper to suit the purpose for which
they are to be used.

GRIND thoroughly on dry wheel (or wet wheel if care is used to prevent
checking).

HEAT TREATMENT OF MILLING CUTTERS, DRILLS, REAMERS, ETC.

THE FIRE.--Gas and electric furnaces designed for high heats are
now made for treating high-speed steels. We recommend them for
treating all kinds of Blue Chip tools and particularly the above
class. After tools reach a yellow heat in the forge fire they must
not be allowed to touch the fuel or come in contact with the blast
or surrounding air.

HEATING.--Tools of this kind should be heated to a mellow white
heat, or as hot as possible without injuring the cutting edges
(2,000 to 2,200 deg.F.). For most work the higher the heat the better
the tool. Where furnaces are used, we recommend preheating the
tools to a red heat in one furnace before putting them in a white
hot furnace.

COOLING.--We recommend quenching all of the above tools in oil
when taken from the fire. We have found fish oil, cottonseed oil,
Houghton's No. 2 soluble oil and linseed oil satisfactory. The
high heat is the important thing in hardening Blue Chip tools.
If a white hot tool is allowed to cool in the open air it will be
hard, but the air scales the tool.

DRAWING THE TEMPER.--Tools of this class should be drawn considerably
more than water-hardening steel for the