Tin plate, or more properly tinned plate, which is so largely employed in the manufacture of saucepans, coffee-pots, tea-kettles, &c. by the tinman is not, as its ordinary name seems to imply, made of tin, but is formed of the best sheet iron, rolled out to the required thickness, and coated on each side with a layer of tin. Copper vessels ought to be invariably tinned inside, to prevent the rusting of the copper by the action of acids. Tinfoil is largely employed for the purpose of preserving moist articles from becoming dry, and is used instead of paper for enclosing fancy soap, chocolate, and other substances of a similar nature. It is also extensively used in the manufacture of looking-glasses, and is sometimes placed behind paper-hangings to exclude the damp of the walls. The most important alloys into the composition of which tin enters are bronze, pewter, bell-metal, and solder. Tin dissolved in acids is largely employed by dyers in fixing or rendering permanent various colours used in dyeing. The preparation termed putty powder is a rust of tin, obtained by exposing the melted metal to the air; it is employed in polishing metals and other articles. [Illustration: Mallet. Soldering Iron. Hammer. Block Hammer.] The tinning of the inner surfaces of cooking utensils and other vessels of capacity is effected by scouring the surface until it is perfectly bright and clean; then heating the vessel, pouring in some melted tin and rolling it about, and rubbing the tin all over the surface with a piece of cloth or a handful of tow; powdered rosin is used to prevent the formation of oxide. Bridle bits, stirrups, and many other small articles, are tinned by immersing them in fluid tin. Tin-plate working, or the forming sheets of tinned iron into a variety of useful vessels and utensils, is carried on by means of bench and hand _shears_, _mallets_, and _hammers_, _steel heads_ and _wooden blocks_, _soldering irons_ and _swages_. In the formation of a vessel, the first operation is to cut the plate to the proper size and form with shears, and, when the dimensions of the article require it, to join them together, which is done either by simply laying the edge of one plate over that of the other, and then soldering them together, or by folding the edges together with laps and then soldering them. Similar joints are required when gores or other pieces are to be inserted, and also at the junction by which a cylinder is closed in. The usual method of forming laps, bends, or folds, for this or other purposes, is to lay the plate over the edge of the bench and to bend it by repeated strokes with a hammer; but a machine is sometimes used for this purpose. [Illustration: Straight Snips. Scotch Snips. Large Shears. Bent Snips.]