QUESTIONS AND PROBLEMS 173 



4. Describe the method by which cellulose can be converted into sugar. 



Express the formation of sulphate of cellulose by an equation. 



5. What are collodion and gun-cotton, and how are they produced ? 



What purpose does the sulphuric acid serve ? Explain how the 

 existence of a hexanitrate of cellulose is evidence of the molecular 

 formula of cellulose being a multiple of CgHigOr,. 



6. State what happens when to solutions of cane sugar and grape sugar, 



solutions of sulphate of copper and then caustic alkali are added. 

 Express the changes in the copper compounds by equations. 



7. How may cane sugar be converted into grape and fruit sugar ? 



Suggest an explanation of the occurrence of the former in unripe, 

 and the latter in ripe fruits. Explain why this conversion is 

 spoken of as a "hydrolytic" change. 



8. Name the chief sources of cane sugar. What is milk sugar, and how 



is it obtained ? Into what sugar is starch first converted by 

 hydrolysis ? 



9. Draw up a scheme illustrating the conversion of carbohydrates of the 



CgllioOs and C12H22O11 groups into carbohydrates of the CgHigOg 

 group. 



10. Identify the carbohydrate. (Starch, inulin, dextrin, cane sugar, or 



grape sugar.) 



11. Find out whether the vegetable substances contain either starch, 



inulin, cane sugar, or grape sugar. (Potato, turnip, mangold, 

 . artichoke, carrot, apple, barley, and malted grain. ) 



The Hydrocarbons. 



12. What is meant by carbonisation? Give an account of the gradual 



carbonisation that goes on in nature, and give examples of 

 artificially carbonised substances. 



13. Distinguish between a hydrocarbon and a carbohydrate. 



14. Give an account of the sources of petroleum and paraffin, the 



products of their fractional distillation, and the several uses of 

 these. 



15. In what respects do the physical properties of the hydrocarbons of 



the paraffin series depend upon their composition ? 



16. Give a full account of the manufacture of coal gas and its purification. 



Of what does coal gas consist, and to what constituents are the 

 illuminating properties chiefly due ? State how the temperature of 

 the retorts affects the quality and quantity of the gas. What are 

 the by-products of coal gas manufacture ? 



17. Describe the structure of a hydrocarbon flame, and state to what the 



luminosity is due. Describe the principle of the Bunsen burner. 



