To prevent lead from sticking to work that has many small corners or grooves, when heated in a lead bath preparatory to hardening, mix lamp black with water or alcohol to the consistency of paint and apply with a brush. Be sure that the mixture is thoroughly dried out before the piece is dipped into the lead bath.
E. W. Norton.
The following receipt for a tempering compound I have found very useful when it was impossible to procure a good grade of steel. This compound will be found specially good for cold chisels, center punches, flat lathe drills, etc., and in fact almost any tool not having irregular forms or thin cutting edges. To 6 quarts of good clear rain water add 1 ounce of corrosive sublimate and 2 pints common salt. Stir until thoroughly dissolved. This compound seems to both harden and toughen steel; the tools are dipped and drawn in the usual manner.
Louisville, Ky. Herrmann G. Kroeger.
To temper small coil springs in a furnace burning wood the springs are exposed to the heat of the flame and are quenched in a composition of the following preparation: To a barrel of fish-oil, 10 quarts of rosin and 12 quarts of tallow are added. If the springs tempered in this mixture break, more tallow is added, but if the break indicates brittleness of the steel rather than excessive hardness, a ball of yellow beeswax about 6 inches in diameter is added. The springs are drawn to a reddish purple by being placed on a frame having horizontally radiating arms like a star which is mounted on the end of a vertical rod. The springs are laid on the star and are lowered into a pot of melted lead, being held there for such time as is required to draw to the desired color. A. L. Monrad.
New Haven, Conn.
Dust or small globules of oil, which sometimes give trouble by collecting at the top of hardening solutions, can be disposed of by placing a piece of ordinary newspaper on top of the solution; the dirt and oil adhere to the paper and are thus readily removed, thereby avoiding the labor of skimming the bath. Emil Tschcdi.
About three years ago we had a new quick-break switch to manufacture in large quantities. One piece of the switch was required to be hard at one end and soft at the other. We tried several methods of annealing so as to leave one end hard, but found that the temper was drawn throughout, and all were rejected. We finally decided that a hot lead bath was the only way that would anneal one end and leave the other end hard, but we then encountered the difficulty of the hot lead sticking to the work. A number of receipts were tried for preventing it without success, but finally I discovered a process that is quick and very cheap. Mix common whiting or cold water paint with wood alcohol and paint the part that is to be annealed. The hot lead will not stick, no matter how long the piece is held in the pot. Of course, in the work mentioned, the pieces were lowered quickly into the hot lead and removed as soon as possible, in order to prevent drawing the temper of the hard end, and then the whole was plunged into a pail of cold water. Water will do as well as alcohol to mix the paint, but alcohol is the most convenient inasmuch as it can be used without waiting for the paint to dry. If water is used, the paint must be thoroughly dry, as otherwise the moisture will cause the lead to fly. E. J. Lawless.