This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
(a) Clean the surface of the steel, and with a fine brush coat the steel with a solution of copper sulphate. The iron reduces the copper to the metallic condition, in which condition it firmly adheres to the steel; then solder in the usual way. (b) Take a suitable-sized piece of tinfoil, and wet in a strong solution of commercial sal-ammoniac; place this between the surfaces to be soldered, and apply a hot iron or gas-flame. The surfaces do not require trimming.
The crack is first soldered with tin, and the bell is heated to dull redness or nearly so for a little time. The tin has the property, when heated above its melting-point to nearly redness, of rapidly dissolving copper, an alloy being thereby formed in the crack of nearly the same composition as the hell itself, and which, being in absolute metallic union with it, is quite as brittle and as sonorous as the other portions of the bell.
To make platinum adhere firmly to gold by soldering, it is necessary that a small quantity of fine or 18-carat gold shall be sweated into the surface of the platinum at nearly a white heat, so that the gold shall soak into the face of the platinum; ordinary solder will then adhere firmly to the face obtained in this manner. Hard solder acts by partially fusing and combining with the surfaces to be joined, and platinum alone will not fuse or combine with any solder at a temperature anything like the fusing point of ordinary gold solder.
The article is first scoured out with strong soda water, and the hole is scraped quite clean. If small enough, it is covered with a drop of solder, applied after the spot has been moistened with "killed spirits." If this plan will not suffice, a larger space must be cleansed and a small patch of tin laid on. When the bottom is seriously impaired, the quickest and best method is to cut it off and replace it by a new one.
All kinds of brass may be soldered with Bath metal solder (70 copper, 21 zinc) or soft spelter, using borax as a flux. A good plan is to spread on a little paste of borax and water and lay a bit of tinfoil on this, then heating till the tin melts and runs, and thus coats the surface. Work previously tinned in this way, can be joined neatly and easily.
These require powdered rosin as a flux, with very thin strips of the more fusible solders, care being taken that the soldering-iron is not too hot.
In laying sheet lead for a flat roof, the joints between the sheets are made either by "rolls," "overlaps," or soldering. In joining by rolls, a long strip of wood 2 in. square, flat at the base and rounding above, is placed at each seam; the edge of one sheet is folded round the rod and beaten down close, and then the corresponding edge of the next sheet is folded over the other. In overlapping, the adjacent edges of the 2 sheets are turned up side by side, folded over each other, and closely beaten down. Soldering is not adopted when the other plans can be carried out.
When a water pipe is burst by frost, the damaged portion must be cut out and replaced by a length of new pipe, in the following manner. The ends to be joined are sawn off square, then the open end of the lower section is enlarged by inserting a boxwood tumpin and driving it down by light blows till the opening is large enough to admit the lower end of the new length, which is rasped thinner all round to facilitate this operation. The top end of the new length and the open end of the upper section are then served the same way. The surfaces to be joined are scraped quite bright, either by a shave-hook or by a pocket-knife, and then fitted together, thus forming a couple of circular ditches, as it were. Into these is sprinkled a little powdered rosin to keep the surfaces bright, and then molten solder is poured in from a ladle till the ditches are quite full. Adhesion between the solder and the pipes is then brought about by passing the point of a hot soldering-iron round the ditches, the heat of the iron being sufficient to liquefy the solder and just fuse the surface of the lead, but it must not be so hot as to melt the lead.