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

Take of gold, 3 parts; silver, 3 parts; copper, 1 part; zinc, 1/2 part.

149.  Gold solder No. 3

Take of gold, 2 parts; silver, 3 parts; copper, 1 part; and zinc 1/2 a part.

The gold, silver, and copper must be fused in a crucible before the zinc is added, or else you cannot keep them in the vessel while heating.  When all are completely fused, they must be well stirred, and run into bars.  Solder No. 1 is for gold 16 carats and upwards; No. 2 is for that 14 carats fine; and No. 3 for lower qualities.  If more zinc is added, it will fuse at a lower heat, but the colour is not so good.

150.  Mock gold

Fuse together 16 parts of copper, 7 of platinum, and 1 of zinc.  When steel is alloyed with 1/500 part of platinum, or with 1/500 part of silver, it is rendered much harder, more malleable, and better adapted for all kinds of cutting instruments.  Note.—­In making alloys, care must be taken to have the more infusible metals melted first, and afterwards add the others.

151.  Britannia metal