Take good clear white course sand, 3 parts; refined solton, 1 part; fosterine, 1 part; rock salt 1 part; borax, 1 part; mix all together. Take 2 pieces of cast iron, heat them in a moderate charcoal fire, occasionally taking them out while heating, and dipping them into the composition, until they are of a proper heat to weld, then at once lay them on the anvil, and gently hammer them together, and if done carefully by one who understands welding iron, you will have them nicely welded together. One man prefers heating the metal, then cooling it in the water of common beans, and heating it again for welding. 137. CAST IRON CEMENT Take of clean borings or turning of cast iron, 16 parts; of sal-ammoniac, 2 parts; and flour of sulphur, 1 part; mix them well together on a mortar, and keep them dry. When required for use, take 1 part of the mixture, and 20 parts of clean borings, mix thoroughly, and add a sufficient quantity of water. Note.--A little grindstone added improves the cement. 138. CASE HARDENING This is the conversion of the surface of wrought iron into steel, for the purpose of adapting it to receive a polish, or to bear friction, &c. The best method in the world of effecting this is by heating the iron to cherry red in a close vessel, in contact with carbonacious material, and then plunging it into cold water. Bones, leather, hoofs, and horns of animals, are best for this purpose, after having been burnt or roasted, so that they can be pulverized. Soot is very frequently used; it answers, but not so well. 139. TO SOFTEN IRON OR STEEL Either of the following simple methods will make iron or steel as soft as lead: 1. Anoint it all over with tallow, temper it in a gentle charcoal fire, and let it cool of itself. 2. Take a little clay, cover your iron with it, temper in a charcoal fire. 3. When the iron or steel is red hot, strew hellebore on it. 4. Quench the iron or steel in the juice, or water, of common beans. 140. SOLDER FOR LEAD Melt 1 part of block tin, and when in a state of fusion, add 2 parts of lead; if a small quantity of this, when melted, is poured upon the table, there will, if it be good, arise little bright stars upon it. Resin should be used with this solder. 141. SOLDER FOR TIN Take 4 parts of pewter, 1 of tin, and 1 of bismuth, melt them together, and run them into thin slips. Resin is also employed in using this solder. 142. SOLDER FOR IRON The best solder for iron is good tough brass, with a little borax. 143. SOLDER FOR COPPER Take of brass, 6 parts; zinc, 1 part; tin, 1 part; melt all together, mix well, and pour out to cool. 144. SOLDER FOR STEEL JOINTS Silver, 19 parts; copper, 1 part; brass, 2 parts; melt all together. 145. HARD SOLDER Fuse together 2 parts of copper, and 1 of zinc. 146. SOLDER FOR SILVER Fuse together 5 parts of silver, and 1 part of brass. 147. GOLD SOLDER No. 1 Take of gold, 4 parts; silver, 3 parts; copper 1 part; and zinc, 1 part. 148. GOLD SOLDER No. 2