Senior Examination Papers, 1891. 
413 
4. Show how to determine the amount of water vapour in the air at any 
given time and place. Point out the causes which tend to equalise the distri- 
bution of water vapour in the atmosphere. 
5. What gases are usually found in solution in rain water ? How may they 
be extracted ? What circumstances increase the solubility of gases in water 
Give examples. 
6. Sulphurous acid, ferrous sulphate, and grape sugar are all reducing 
agents : explain what this means, and give examples in illtistration of their 
reducing action- 
7. Give some accotmt of the occurrence in nattire, and of the properties, of 
alumina and its hydrate. 
8. WTiat are the grounds for regarding carbonic acid as a dibasic acid ? 
Calculate the weight of slaked lime needed to convert 1,000 grams of carbonate 
of soda into caustic soda, and to convert a like weight of the bicarbonate also 
into caustic soda. (Na = 23, Ca = 40.) 
9. What is the relation between urea and ammonia ; and how may urea be 
made to yield ammonia ? 
10. ExplaiQ the chemical relations of starch, sugar, and cellulose. Plants 
produce such substances from carbonic acid and water under the influence of 
sunshine : show on what principle sunshine is necessary for the result. 
EXAMINATION IN CHEMISTRY. 
MAxnnm Nomeeb of Maeks, 200. Pass Ncmbee, 100. 
B. AGBICULTtTRAL ChEMISTET. 
Thursday, May lith,/rom 2 p.m. till 5 p.m. 
1. The occurrence of chloride of sodium (common salt) In a soil may be 
the cause of its infertility, so also may the presence of certain compoimds of 
iron. State whence these may arise, in wha'- quantity the former (chloride of 
sodium) is known to be injurious, and how they may be removed. 
Account for the fact that, despite the above, both common salt and sulphate 
of iron may be used as manures. 
2. Take the case of a country which exports to a large extent its grain 
crops, and returns only about one-quarter of the straw in the form of manure, 
this being practically the only manurial source available, what would you say 
should be the agricultural condition of the soil as regards its capability for 
producing future crops ? Explain in what ways natural richness or judicious 
rotation might afEect the result, at least temporarily. 
3. What is an " oil-cake " 2 
What are the principal objections to the use of the term " oil-cake," and 
why should fanners insist upon being supplied with " pure linseed-cake " ? 
4. Which are the principal " sugars " that are met with in agricultural 
chemistry ? Give the chief occurrences and properties of each. 
5. Discuss, quantitatively, the rainfall as a supplier of food to plants. 
What causes may produce variations in its composition ? 
6. Explain what differences a field may exhibit in the succession of crops 
grown upon it, according as to whether it has been old pasture land recently 
ploughed up, or has been for a long time arable. To what chemical causes 
may these be due ? 
7. Give examples of the effects of high manuring on crops, as regards 
quantity, maturity, and chemical composition. 
8. What is animal charcoal ? How is it produced, and to what does it owe 
its purifying power ? How does wood charcoal differ from it ? 
