BRITANNIA METAL, The present composition of britannia metal at Birmingham is usually 90 tin ± 8 antimony 2 copper, without any zinc or bismuth; although .some manufacturers deviate a little from this formula, by adding one or both of the :metals last named. The manufacture was began at Sheffield by Hancock and Jessop, in 1770; it reached Birmingham towards the close of the century, and made gradual prog .re.:s. At first, the articles were made by stamping with dies, and soldering up into form.; this being a slow operation, rendered the articles expensive. Afterwards, the curious process of metal spinning was introduced; and this, with the subsidiary opera lion of swagging, rendered a great reduction in price possible. In the spinning proc ess, a thin sheet or piece of britannia metal is placed upon a wooden model shaped like the article to be made; the model is made to rotate in a lathe; and burnishers and other tools are employed to press the yielding metal into all the curvatures of the model.
Ductility is an essential quality to the attainment of this end with the metal; how complete it is, may be seen in such articles as britannia metal teapots and dish-covers, the principal forms of which are not given by hammering, stamping, or casting, but by spinning. Besides spinning and swagging, the processes include stamping, soldering, casting, and polishing. W hen electro-pluting was introduced, an increased use of britannia metal arose, as it forms a good ground or basis for the deposited silver. Britannia metal spoons and ladles, made by casting, stamping, and burnishing, have been nearly driven out of the market by German silver; but the former metal is more largely used than ever for hot-water jugs, soup tureens, gravy-dishes, vegetable and side dishes, drain bottles, drinking-cups, sandwich cases, wine-coolers, soap-boxes, liquor frames, cruets, waiters, trays, etc.; and as a basis for electroplate. Birmingham is the chief seat of the manufacture.