Melt separately 4 lb. of copper, 12 lb. best quality tin, 8 lb. regulus of antimony, and 12 lb. more of tin while the composition is in a melted state. Pour the antimony into the tin, then mix with the copper away from the fire in a separate pot.
In melting the composition, it is better to keep a small quantity of powdered charcoal on the surface of the metal. The above composition is walled "hardening." For lining-metal, take 1 lb. of hardening and melt it with 2 lb. of tin, which produces the lining-metal for use. Thus the proportions for lining-metal are, 4 lb. of copper, 8 lb. of regulus of antimony, and 96 lb. of tin.
The article to be lined, having been cast with a recess for the lining, is to be nicely fitted to a "former," which is made of the same shape as the bearing. Drill a hole in the article for the reception of the metal, say a half or three-quarters of an inch, according to the size of it. Coat over the part not to be tinned with a clay wash, wet the part to be tinned with alcohol, and sprinkle on it powdered sal-ammoniac; heat it till a fume arises from the sal-ammoniac, and then immerse in melted tin, taking care not to heat it so that it will oxidise. After the article is tinned, should it have a dark colour, sprinkle a little sal-ammoniac on it, which will make it a bright silver colour. Cool it gradually in water, then take the "former," to which the article has been fitted, and coat it over with a thin clay wash, and warm it so that it will be perfectly dry; heat the article until the tin begins to melt, lay it on the "former" and pour in the metal, which should not be so hot as to oxidise, through the drilled hole, giving it a head, so that as it shrinks it will fill up.
After it has sufficiently cooled, remove the "former."
A shorter method may be adopted when the work is light enough to handle quickly; namely, when the article is prepared for tinning, it may be immersed in the lining metal instead of the tin, brushed lightly in order to remove the sal-ammoniac from the surface, placed immediately on the former and lined at the same heating. (See also iii. 41.)