Tin.-Solder for tin plates, is made of one or two parts of tin, and one of lead. Before soldering, the surfaces must be quite bright and close together ; and the contact of air must be excluded during the operation, else the heat will tarnish the surface and prevent the adhesion of the solder : the borax and resin commonly in use, effect this. The best plan is to clean the surfaces with muriatic acid saturated with tin : this method is invariably adopted by watchmakers and opticians, who never use borax and resin. The point of the solderingtool must be filed bright.
Copper, to tin.-Clean the copper well with sandstone ; heat it, and rub it with sal-ammoniac till it is quite clean and bright; the tin, with some powdered resin, is now placed on the copper, which is made so hot as to melt the tin, and allow it to be spread over the surface with a bit of rag. A very little tin is used in this way : it is said that a piece as big as a pea, would tin a large saucepan; which is at the rate of twenty grains of tin to a square foot of copper.
Raw Hides.-Dressing Hides.-Skins that have been dressed are essential to a traveller in an uncivilised country, for they make his packing-straps, his bags, his clothes, shoes, nails, and string, therefore no hide should be wasted. There is no clever secret in dressing skins : it is hard work that they want, either continual crumpling and stretching with the hands, or working and trampling with the feet. To dress a goat-skin will occupy one person for a whole day, to dress an ox-hide will give hard labour to two persons for a day and a half, or even for two days. It is best to begin to operate upon the skin half an hour after it has been flayed. If it has been allowed to dry during the process, it must be re-softened by damping, not with water-for it will never end by being supple, if water be used-but with whatever the natives generally employ : clotted milk and linseed-meal are used in Abyssinia; cow-dung by the Caffres and Bushmen. When a skin is put aside for the night, it must be rolled up, to prevent it from becoming dry by the morning. It is generally neces-