GILDING 641 



E. Shelf for the brushing operations. 



B B. Coal cellarets. 



o. Forge for the deadening process. 



0. Furnace for the same. 



M. An opening into the furnace of appel, by which vapours may be let off from any 

 operation by taking out the plug at M. 



1. Cask in which the pieces of gilded brass are plunged for the deadening process. 

 The vapours rising thence are carried up the general chimney. 



j j. Casement with glass panes, which serves to contract the opening of the hearths, 

 without obstructing the view. The casement may be rendered moveable to admit 

 larger objects. 



H H. Curtains of coarse cotton cloth, for closing at pleasure, in whole or part, one or 

 several of the forges or hearths, and for quickening the current of air in the places 

 where the curtains are not drawn. 



Q. Opening above the draught furnace, which serves for the heating of the poelon au 

 mat (deadening pan). 



Gilding on polished iron and steel. If a nearly neutral solution of gold in muriatic 

 acid be mixed with sulphuric ether, and agitated, the ether will take up the gold, and 

 float above the denser acid. When this auriferous ether is applied by a hair-pencil to 

 brightly-polished iron or steel, the ether flies off, and the gold adheres. It must be 

 fixed by polishing with the burnisher. This gilding is not very rich or durable. In 

 fact the affinity between gold and iron is feeble, compared with that between gold and 

 copper and silver. But polished iron, steel, and copper, may be gilded with heat, by 

 gold-leaf. They are first heated till the iron takes a bluish tint, and till the copper has 

 attained to a like temperature ; a first coat of gold-leaf is now applied, which is pressed 

 gently down with a burnisher, and then exposed to a gentle heat. Several leaves 

 either single or double are thus applied in succession, and the last is burnished down 

 cold. 



Mr. Elkington obtained a patent, in June 1836, for gilding copper, brass, &c., by 

 means of potash or soda combined with carbonic acid, and with a solution of gold. 

 Dissolve, says he, 5 oz. troy of fine gold in 52 oz. avoirdupois of nitro-muriatic acid of 

 the following proportions : viz. 21 oz. of pure nitric acid, of spec. grav. 1'45, 17 oz. 

 of pure muriatic acid, of spec. grav. 1*15, with 14 oz. of distilled water. 



The gold being put into the mixture of acids and water, they are to be heated in 

 a glass or other convenient vessel till the gold is dissolved ; and it is usual to continue 

 the application of heat after this is effected, until a reddish or yellowish vapour ceases 

 to rise. 



The clear liquid is to be carefully poured off from any sediment which generally 

 appears, and results from a small portion of silver, which is generally found in alloy 

 with gold. The clear liquid is to be placed in a suitable vessel of stone ; pottery ware 

 is preferred, Add to the solution of gold 4 gallons of distilled water, and 20 pounds 

 of bicarbonate of potash of the best quality ; let the whole boil moderately for 2 hours, 

 the mixture will then be ready for use. 



The articles to be gilded having been first perfectly cleaned from scale or grease, 

 they are to be suspended on wires, conveniently for a workman to dip them in the 

 liquid, which is kept boiling. The time required for gilding any particular article 

 will depend on circumstances, partly on the quantity of gold remaining in the liquid, 

 and partly on the size and weight of the article ; but a little practice will readily give 

 sufficient guidance to the workman. 



Supposing the articles desired to be gilded be brass or copper buttons, or small 

 articles for gilt toys, or ornaments of dress, such as earrings or bracelets, a consider- 

 able number of which may be strung on a hoop, or bended piece of copper or brass 

 wire, and dipped into the vessel containing the boiling liquid above described, and 

 'moved therein, the requisite gilding will be generally obtained in from a few seconds 

 to a minute ; this is when the liquid is in the condition above described, and depend- 

 ing on the quality of the gilding desired ; but if the liquid has been used some time, 

 the^quantity of gold will be lessened, which will vary the time of operating to produce 

 a given effect, or the colour required, all of which will quickly be observed by the 

 workman ; and by noting the appearance of the articles from time to time, he will 

 know when the desired object is obtained, though it is desirable to avoid as much as 

 possible taking the articles out of the liquid. 



When the operation is completed, the workman perfectly washes the articles so 

 gilded with clean water; they may then be submitted to the usual process of 

 colouring. 



If the articles be cast figures of animals, or otherwise of considerable weight, com - 

 pared with the articles above mentioned, the time required to perform the process will 

 be greater, 

 VOL. II. T T 



