Chemical Scietice. 183 



muriatic acid. This preparation would probably be of use in 

 dyeing and the arts. 



7. On testing different Metals by Cupellation. — M. Chaudet 

 has made some experiments on the means of detecting the metals 

 of alloys by the cupelling furnace, and they promise useful 

 application. The testing depends on the appearances exhibited 

 by the metals and their alloys, when heated on a cupel. Pure 

 tin, when heated this way, fuses, becomes of a greyish black 

 colour, fumes a little, exhibits incandescent points on its sur- 

 face, and leaves an oxide, which, when withdrawn from the fire, 

 is at first lemon yellow, but when cold, white. Antimony melts, 

 preserves its brilliancy, fumes, and leaves the vessel coloured 

 lemon-yellow when hot, but colourless when cold, except a few 

 spots of a rose tint. Zinc burns brilliantly, forming a cone of oxide, 

 and the oxide much increased in volume, is when hot, greenish, 

 but when cold perfectly white. Bismuth fumes, becomes covered 

 with a coat of melted oxide, part of which sublimes, and the 

 rest enters the pores of the cupel ; when cold, the cupel is cf a 

 fine yellow colour, with spots of a greenish hue. Lead resembles 

 bismuth very much; the cold cupel is of a lemen-yellow colour. 

 Copper melts, and becomes covered with a coat of black oxide ; 

 sometimes spots of a rose tint remain on the cupel. 



Alloys. Tin 75, antimony 25, melts, becomes covered with a 

 coat of black oxide, has very few incandescent points. When 

 cold the oxide is nearly black, in consequence of the action of 

 the antimony. A ^J^ part of antimony may be ascertained in 

 this way in the alloy. An alloy of antimony, containing tin, 

 leaves oxide of tin in the cupel; jij^ part of tin may be detected 

 in this way. An alloy of tin and zinc gives an oxide, which, 

 whilst hot, is of a green tint, and resembles philosophic wool in 

 appearance. An alloy, containing 99 tin, 1 zinc, did not pre- 

 sent the incandescent points of pure tin, and gave an oxide of 

 greenish tint, when cold. Tin 95, bismuth 5 parts, gave an 

 oxide of a grey colour. Tin and lead gave an oxide of rusty brown 

 cqlour. An alloy of lead and tin, containing only one per cent. 

 of the latter metal, when heated, does not expose a clean sur- 

 face like lead, but is covered at times by oxide of tin. Tin 75, 



