A tempering solution used for high heats may be composed of two parts Chili saltpeter and one part nitrate of soda. This tempering solution is used only at high temperatures, as it becomes solid at about 500 degrees F. It Is used in place of tempering oils, as they often thicken after short use, and will flash or ignite at about 600 degrees F., and often at a lower temperature. It should be used in connection with a tempering furnace, the heat being gaged by a thermometer. The thermometer should be removed when the day's work is over. At night, two iron plugs, with a fairly liberal taper per foot, and long enough to reach from the inside bottom of the tank containing the bath, to about four inches above the top of the solution, should be placed vertically with the small end of the taper down, and some little distance apart. These should be permitted to stay in the solution when it solidifies. On the following morning, these iron plugs should be unscrewed and removed. The holes left in the solidified solution by these plugs afford an escape for gases that form in reheating the bath. E. S. Wheeler.
Alloys of various composition are successfully used for drawing colors on steel. To draw to a straw color use 2 parts of lead and 1 part of tin, and melt in an iron ladle. Hold the steel piece to be drawn in the alloy as it melts and it will turn to straw color. This mixture melts at a temperature of about 437 degrees F. For darker yellow, use 9 parts of lead to 4 parts of tin, which melts at 458 degrees F. For purple, use 3 parts of lead to 1 part of tin, the melting temperature being 482 degrees F. For violet, use 9 parts of lead to 2 parts of tin, which melts at 594 degrees F. Lead without any alloy will draw steel to a dark blue.
Cleveland, Ohio. Max Dehne.