How to Caseharden Large Pieces of Steel.—­A box of cast or wrought iron should be provided large enough to hold one or two of the pieces, with sufficient room all around to pack well with the casehardening materials, which may be leather scrap, hoof shavings, or horn shavings, slightly burned and pulverized, which may be mixed with an equal quantity of pulverized charcoal.  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 0.7854.  Multiply this product by the height (all in inches).  Then divide by 231 for the number of gallons.

A Useful Recipe.—­For stopping the joints between slates or shingles, etc., and chimneys, doors, windows, etc., a mixture of stiff white-lead paint, with sand enough to prevent it from running, is very good, especially if protected by a covering of strips of lead or copper, tin, etc., nailed to the mortar joints of the chimneys, after being bent so as to enter said joints, which should be scraped out for an inch in depth, and afterward refilled.  Mortar protected in the same way, or even unprotected, is often used for the purpose, but it is not equal to the paint and sand.  Mortar a few days old (to allow refractory particles of lime to slack), mixed with blacksmith’s cinders and molasses, is much used for this purpose, and becomes very hard and effective.

Test for Hard or Soft Water.—­Dissolve a small quantity of good soap in alcohol.  Let a few drops fall into a glass of water.  If it turns milky, it is hard; if not, it is soft.