1 74 CHEMISTR Y FOR A GRICUL TUR A L STUDENTS 



i8. Distinguish between the quantity of heat produced by the combustion 

 of fuels, and the temperature attained. Upon what will the latter 

 depend ? Explain why a Bunsen flame is hotter than a luminous 

 gas flame, and why combustion in oxygen gives rise to a higher 

 temperature than combustion in air. 



19. How many grams of water could be raised 1° in temperature by the 



combustion of i gram of carbon and of i gram of hydrogen 

 respectively. Explain why the heat of combustion of marsh gas 

 should be greater than that of olefiant gas. Why should dry wood 

 produce more heat when burned than wet wood, and charcoal 

 more heat than either ? 



20. Tabulate the hydrocarbons referred to, assigning each to its proper 



series, and showing the simple relation that exists between the 



members of each series. 

 *2i. Prepare a pure specimen of hexane from the gasoline. 

 *22. Determine the relative density of the coal gas (air=i). 



The Alcohols : Fermentation. 



23. Fully describe the preparation of alcohol from cane sugar by 



fermentation. How can the alcohol be dried and rectified ? 



24. Of what does yeast consist? Distinguish between the "organised" 



and the " soluble " ferment, and illustrate by equations the 

 principal change in sugar which each brings about. 



25. Describe the use of yeast in bread-making, and the changes that 



go on during the raising and baking of bread. Name two means 

 of raising bread other than by yeast. 



26. What is "proof spirit"? How could a spirit 56 per cent, over proof 



and a spirit 56 per cent, under proof be converted into proof spirit ? 



27. What is meant by an "organic radicle," and of what organic radicle 



is alcohol the hydroxide ? In what respects does alcohol resemble 

 in its properties an inorganic hydroxide ? 



28. Give an account of the preparation of nitrous ether. 



29. What is the action of potash upon nitrous ether? Give examples of 



inorganic salts which are decomposed by the same means. 



30. Point out the similarity in the relation of water to hydrogen with that 



of ethyl alcohol to ethane. What alcohols are present in fusel oil, 

 wood spirit, and coal tar oil, and to what hydrocarbons does each 

 " correspond " ? 



31. The physical properties of the hydrocarbons were found to vary with 



the molecular weights ; does this also hold good for the alcohols ? 

 Give examples. 



