Pack the pieces to be
casehardened in the iron box so as not to touch each other or the box.
Put an iron cover on the box and lute with clay. Heat gradually in
a furnace to a full red, keep at an even temperature for from 2 to
4 hours, raise the heat to a cherry red during the last hour, then
remove the cover and take out the pieces and plunge endwise vertically
in water at shop temperature; 2 per cent. of hydrochloric acid in the
water improves its tempering qualities and gives the metal an even
gray color.
A Good and Cheap Preparation to Put on Friction Matches.--The igniting
composition varies with different makers. The following recipes may
be taken as fairly representative, the first being the best: 1.
Phosphorus by weight, 1/2 part; potassium chlorate, 4 parts; glue,
2 parts; whiting, 1 part; finely powdered glass, 4 parts; water, 11
parts. 2. Phosphorus by weight, 2 parts; potassium chlorate, 5 parts;
glue, 3 parts; red lead, 1-1/2 parts; water, 12 parts. 3. A German
mixture for matches. Potassium chlorate, 7.8 parts; lead hyposulphite,
2.6 parts; gum arabic, 1 part.
To Find How Much Tin Vessels Will Hold.--For the contents of
cylinders: Square the diameter, and multiply the product by 0.7854.
Again, multiply by the height (all in inches). Divide the product by
231 for gallons. For the frustum of a cone: Add together the squares
of the diameters of large and small ends; to this add the product of
the diameter of the two ends. Multiply this sum by 0.
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