EXTRACTION OF METALS. 223 



to act as a "flux," i.e., a substance that will promote fusion. 

 Heat the whole red hot in a well covered crucible ; the iron will 

 combine with the sulphur of the sulphide of antimony and set 

 free the antimony, so that on pouring out the hot fluid contents 

 of the crucible you will have two kinds of substances, metallic 

 antimony, and the resulting sulphide of iron and flux, &c., which 

 can be easily detached from the antimony when cold. 



Expt. 267. To obtain Mercury from Vermilion. Vermilion 

 consists of sulphide of mercury, i.e., mercury combined with 

 sulphur. When powdered and heated with iron filings the same 

 kind of action takes place as with sulphide of antimony ; the iron 

 combines with the sulphur, and the mercury is liberated. As 

 mercury is a volatile metal, this experiment cannot be performed 

 in a crucible ; but if carried out in a distilling or subliming vessel 

 where the evolved vapours can be recondensed, globules of quick- 

 silver are easily obtained. Mix powdered vermilion with its own 

 weight of fine iron filings and heat a small quantity of the mixture 

 in a test-tube ; a sublimate will form in the upper part of the tube, 

 consisting of fine globules of mercury mixed with a little unde- 

 composed sulphide of mercury, which sublimes unchanged. 



Expt. 268. To obtain Metallic Copper from Oxide of Copper 

 by means of Hydrogen. Inside a piece of hard glass tubing ("com- 

 bustion tubing "), six or eight inches long and half an inch diameter, 

 place some fragments of oxide of copper, holding the tube hori- 

 zontally and pushing in the pieces with a pencil or glass rod until 

 they are in the centre of the tube, the ends being clear. Fix in 

 one end of the tube a perforated cork with a bit of quill glass 

 tubing passing through, and by means of a bit of india-rubber 

 tubing connect this with the delivery tube of a hydrogen generator, 

 as represented in fig. 95. Carefully heat the centre of the tube 

 where the copper oxide lies with a Bunsen gas flame or spirit lamp, 

 and when the copper is pretty hot, lead a moderately rapid current 

 of hydrogen through the tube. The hydrogen will act on the 

 oxide of copper, taking away the oxygen therefrom and leaving 

 metallic copper; so that the result of the action will be that 

 water vapour is formed and issues as steam at the far end of the 

 tube, part condensing to liquid water at the cool end, so as to form 

 visible drops ; whilst the black fragments of oxide of copper 

 become red, owing to the change in their composition to spongy 

 copper. If the quantity of oxide of copper treated is sufficiently 

 large and the hydrogen supply pretty rapid, the black fragments 

 will become visibly red hot and glow, especially in a darkened 

 room. This shows that the action as a whole is accompanied by 

 the production of heat. 



