CHEMICAL COMBINATION. 



187 



Fig. 80. Candle Flame and Tube. 



Expt. 205. To combine Copper and Sulphur together. Fill 

 a large test-tube with loosely packed thin copper turnings, and 

 then introduce some flowers of sulphur, shaking the tube so that 

 the flowers may be toler- 

 ably equally spread about 

 amongst the copper turn- 

 ings. No change whatever 

 takes place, the copper and 

 sulphur being solids. Now 

 heat the tube in a spirit lamp 

 or Bunsen burner flame, 

 holding it by means of a 

 test-tube holder (fig. 10); 

 the sulphur will soon begin 

 to melt, and as soon as it is 

 liquid it will begin to act 

 on the copper; heat is 

 developed, and by and by, 

 when the sulphur is nearly boiling, the copper will unite with 

 the sulphur so rapidly that the whole mass becomes visibly red 

 hot, the copper actually burning in the act of combination with 

 the sulphur. When the action is over and the contents of the 

 tube are cool enough to handle they will be found to consist 

 chiefly of a black brittle substance easily rubbed to powder in 

 a mortar and quite different from either the original sulphur or 

 copper ; this substance is the product of the combination of the 

 two, and is termed copper sulphide. 



Expt. 206. To combine Iron and Sulphur. Make a mixture 

 of two parts iron filings and one flowers of sulphur, and heat it in a 

 test-tube as in the last experiment ; when the mass is sufficiently 

 hot combination will take place between the iron and sulphur, 

 with the production of heat sufficient to make the whole glow 

 visibly ; the product is termed iron sulphide, and, as shown in 

 Expt. 13, will produce the evil-smelling gas sulphuretted hydrogen 

 when treated with hydrochloric acid, which the original iron 

 filings would not do, hydrogen only being formed by the action of 

 the acid on them. A solid iron rod heated nearly white hot and 

 touched with a stick of brimstone will rapidly combine therewith, 

 fused sulphide of iron dropping down and the rod being apparently 

 melted away. 



In these experiments the chemical action takes place between 

 the solid metal and the sulphur, either in the melted state or in 

 the state of vapour, but not when the sulphur is solid ; the pro- 

 duct being in each case a substance which is solid at the tempera- 



