EXERCISES
1. Why does charcoal usually burn with no flame? How do you account for the flame sometimes observed when it burns?
2. How do you account for the fact that a candle burns with a flame?
3. What two properties must the mantle used in the Welsbach lamp possess?
4. (a) In what respects does the use of the Welsbach mantle resemble that of lime in the calcium light? (b) If the mantle were made of carbon, would it serve the same purpose?
5. Would anthracite coal be suitable for the manufacture of coal gas?
6. How could you prove the formation of carbon dioxide and water in the combustion of illuminating gases?
7. Suggest a probable way in which natural gas has been formed.
8. Coal frequently contains a sulphide of iron. (a) What two sulphur compounds are likely to be formed when gas is made from such coal? (b) Suggest some suitable method for the removal of these compounds.
9. Why does the use of the bellows on the blacksmith's forge cause a more intense heat?
10. What volume of oxygen is necessary to burn 100 l. of marsh gas and what volume of carbon dioxide would be formed, all of the gases being measured under standard conditions?
11. Suppose a cubic meter of Pennsylvania natural gas, measured under standard conditions, were to be burned. How much water by weight would result?