Chemical Aids to Art. 183 



or silver on platinum, may be formed, while in the case of 

 gold, at all events, the groundwork metal of copper or brass 

 would scarcely have shown an appreciable contrast of colour. 



Let us now consider a second process, not altogether dis- 

 similar to that just described, but in which silver instead of 

 platinum is concerned. We have already referred to dama- 

 scening, in which iron is inlaid with gold or silver by a purely 

 mechanical process. The same result may, however, be at- 

 tained with silver as the inlay, in a totally differ ent manner. 

 The hollows destined to receive the silver patterns are engraved 

 or etched by acid in the iron or steel, but, instead of using 

 wires of metallic silver to fill these hollows, a chemical com- 

 pound of silver is employed. This compound is the nitrite of 

 silver, and is easily prepared by adding pure nitrite of sodium, 

 dissolved in water, to a solution of nitrate of silver. When 

 no more precipitate falls on further additions of the nitrite of 

 sodium solution, the pale straw-coloured substance, which is 

 nearly pure nitrite of silver, is to be collected on a filter, a 

 little cold water poured upon it, and then, while still moist, 

 pressed into the grooves in the iron which have been prepared 

 for its reception. Here it is permitted to dry, and, when it is 

 perfectly free from moisture, the next step in the process may 

 be taken. This step consists in heating the metallic plate or 

 other object over a lamp or fire till the whole of the nitrous 

 acid has been resolved into gases, which escape, and metallic 

 silver, which is left behind as a spongy mass. With an agate 

 or steel burnisher the whole of the lines of silver must be 

 followed, using considerable pressure to force the metal into 

 the grooves and lines, any superfluous silver being rubbed 

 away with very fine emery-powder, or a fine pencil-like hone. 



Many metals besides iron may be ornamented with beautiful 

 designs in inlaid silver by means of the process just described. 

 Among these may be named copper, brass, and bronze ; even 

 gold and platinum admit of similar treatment. In all cases 

 an easy method of etching out the hollows of the design is 

 applicable. Both sides of the plate to be inlaid are covered 

 with a resisting composition (beeswax melted with a little 

 spirits of turpentine), the designs are boldly drawn, so as to 

 lay bare the metal, and then the prepared object is to be 

 immersed in the etching fluid. Weak nitric acid answers for 

 all the common metals we have before named. When the 

 design has been etched to a sufficient deptli the object is 

 withdrawn from the acid, and (after removal of the composi- 

 tion by means of spirits of turpentine) passed through the 

 flame of a spirit-lamp, to burn off the last traces of the wax 

 and turpentine. 



This new process of inlaying silver no doubt requires some 



