CHARRING OF CARBON COMPOUNDS 39 



a small bundle of green leaves, such as grass. If you have it, 

 put in also a petal from a red rose or a red carnation. What 

 is the effect on each of these? 



b. Iron and Sulphur. On a clean paper mix thoroughly a 

 teaspoonful of powdered sulphur and half as much powdered 

 iron or fine iron filings. Put the mixture into a test tube, hold 

 the test tube by a wire holder, if possible, and heat the bottom 

 of the test tube red hot. The heating should start a brilliant 

 glow, and this should travel through. the mixture as the iron 

 and sulphur unite to form iron sulphide. Note the appearance 

 of the substance when it is cool; you will need to break the test 

 tube. 



c. Hydrogen Sulphide. Put a very small lump of the iron 

 sulphide into an evaporating dish or watch glass, and add to it 

 1 or 2 cu. cm. of dilute hydrochloric acid. Note what happens, 

 and learn the odor of the gas (hydrogen sulphide) that is given 

 off. What is it like? 



EXERCISE 38 

 CHARRING OF CARBON COMPOUNDS 



Apparatus and Materials. Small iron dish (cake or muffin tin), 

 "tin" cover to fit into it (Fig. 19), ring stand, burner or stove; pieces 

 of wood, coal, and starch; sugar. 



a. In a small iron dish (Fig. 19) put some small pieces of 

 wood (pine is best), and push the cover tightly into the dish. 

 The cover should be circular; it may be cut out of a sheet of 

 "tin," or the tin of a can. It should fit into the iron dish about 

 half way from top to bottom. In the center of the cover have 

 a hole of about the diameter of a small , 



pencil. Y~~ 7 



Heat the iron dish over a flame or on \ r~ % / 

 a hot stove, lighting the gas that escapes FIG. 19. 



