38 LABORATORY EXERCISES 



teaspoonful of powdered manganese dioxide and about 2 tea- 

 spoonfuls of concentrated hydrochloric acid. Usually the gas 

 is formed at once; if it should come off slowly, set the bottle in a 

 pail of warm water. What is the color of the gas? Wave a 

 little toward your nose, and smell of it cautiously. 

 What is its odor? 



6. Hang in the bottle of the gas a piece of moist 

 litmus paper (either color), a piece of moist colored 

 cloth (such as cheap, red cheesecloth), a piece of 

 paper with ink writing upon it, and a small bundle 

 of green leaves, such as grass or parsley. What 



FIG. is. happens to them? Leave them some time if the 

 changes are slow. 



Remove the cover of the bottle for a moment, and put a 

 burning match into the gas. Does the gas burn? Does the 

 splinter continue to burn? 



EXERCISE 37 

 SULPHUR 



Apparatus and Materials. Wide-mouth bottle, or fruit jar, with 

 cardboard cover; evaporating dish or watch glass, test tube holder; 

 combustion spoon and test tube (for a way of making these out of tin, 

 see Introduction); sulphur, powdered iron, dilute hydrochloric acid, 

 red litmus paper, grass, red rose or carnation petal. 



a. Sulphur Dioxide. In a wide-mouth bottle or fruit jar 

 burn some sulphur. You will need a long-handled spoon 

 (combustion spoon) and a cardboard cover with a hole for the 

 spoon handle. Light the sulphur in a flame before putting it 

 into the bottle of air. Let the sulphur burn as long as it will. 

 Why does it finally stop burning? 



Wave a little of the gas toward the nose, and learn its odor. 

 Into the bottle (or jar) of gas put a piece of moist red litmus and 



