GOLD CUTTING or LAPPING in jewellery consists in pressing articles against a rapidly revolving disc or “lap,” composed of lead and tin, to the surface of which fine emery has been applied. The faces of the article which have thus been “cut” are subsequently polished on a “bob,” that is on a wheel covered with leather on its edge or circumference.[52] COLOURING in jewellery refers to a rich gold colour obtained on gold articles. The process at first could be applied only to jewellery of high quality, but now 15 and 18 carat gold is coloured. The articles are heated to dull redness to destroy grease and dirt, then hung on platinum wires and immersed in a boiling mixture of salt, saltpetre, and muriatic acid and water. After drying out in sawdust they are scratch-brushed.[52] There are many extremely interesting processes in the trades of our town besides those which apply exclusively to the metal trades, but for these I have no space. Those who wish for full information respecting the history, position, and general character of the Birmingham industries, must consult “Birmingham and the Midland Hardware District,” edited by Mr. Sam. Timmins. This volume, which was published on the occasion of the visit of the British Association to the town in 1865, is exhaustive, describing the trades as they then existed. In order, however, to supplement Mr. Timmins’ book, application has been made to various gentlemen who have been good enough to provide the following short notices (or the substance of them) of the various trades referred to at length in the volume. In addition there are some notices of industries which have been introduced since the year 1865. SUPPLEMENTARY DETAILS OF BIRMINGHAM TRADE SINCE 1865. =Introductory Note.=--The references to “Birmingham and the Midland Hardware District” volume are quoted as “B.,” followed by a number indicating the page. Thus (B. 77) means, _See “Birmingham and the Midland Hardware District”, page 77_. The trades are arranged alphabetically. =Assay Office of Birmingham.=--[H. WESTWOOD].--(B. 499). The assay marks continue to be so highly valued by the public that all goods are now sent to be assayed and marked except those of the commonest quality, and a few richly wrought articles that would be injured in the process.[53] The statistics of the Assay Office form an index to the condition of the gold and silver trades of the town. The following tables are a continuation of those given by Mr. Ryland (B. 507). WEIGHT OF GOLD AND SILVER WARES ASSAYED AND MARKED IN BIRMINGHAM. Year ends Gold. Silver. June 24th oz. oz.