All surfaces which will be soldered should have been well cleaned beforehand and tinned with the very fusible bismuth solder that must be used for the purpose. Dont have the bit very hot, for fear of melting the zinc; and while soldering press the parts together to make a good joint. Solder over all heads of tacks.
The Outer Casing is of -inch match-boarding, screwed to the frames. The insulation spaces are packed as the boards are added, thin slips boing fitted at corners to prevent the material shifting when the chest is turned over. Pack %&smm mm sawdust close, rapping the wood to make it settle; but treat slag wool more gently, to avoid crushing the fibres. The upper ends of the sides should project slightly beyond the top frame, leaving a little spare for planing off neatly when the boards have all been fixed.
The legs are of 2-inch by 2-inch batten, shouldered on two adjacent faces to be flush with the outside of the chest. The bottom, of -J-inch matchboards, has square notches at the corners for the legs. Before it is added, fit the drain pipe, soldered at the top to the lining. Then fit two strips of bottom, notched to fit the pipe, and pull the pipe till the lining touches the inner casing. It is secured in this position by soldering it to the collar b. Placing the insulating material and finishing the bottom follow.
Cover the top edges of the chest with strips of zinc, lapping downwards over the lining, to which they are soldered. The joint between lid and chest need not be perfectly airtight, as a little ventilation is a good thing, and cold air does not rise.
The woodwork should be given two good coats of varnish outside, to keep out damp.