xr.ii Agricultural Education — Examination Papers, 1886. 
2. What are the principal differences between distilled water, rain- 
water, a soft river-water, a hard weU- water, and sea-water? How do 
you suppose these differences arise ? 
3. What is meant by " water of crystallisation " ? Give the 
formulae of any three salts containing water of crystallisation. 
4. If for the purpose of chemical analysis you wish to obtain a 
current of dry and pure air (oxygen and nitrogen), how could you 
get this? 
5. Name the principal compounds which nitrogen forms with 
oxygen, assigning to each its formula. How would you test for a 
nitrate ? 
6. Describe briefly the manufacture of oil of vitriol of commerce. 
7. In what forms is silver found in nature ? Give any process by 
■which the pure metal is obtained in quantity. 
8. How would you distinguish between the sulphides of the follow- 
ing metals : — copper, mercury, lead, zinc, arsenic, iron ? 
9. What is white lead ? Describe its preparation. 
10. Define in chemical language, as nearly as you can, the follow- 
ing : — galvanised iron, brass, red lead, porcelain, spirits of hartshorn, 
bleaching-powder, aqua regia, soda crystals, sal-volatile, dolomite. 
C. MECHANICS AND NATURAL PHILOSOPHY. 
November 10th, 1886. 
(Three Hours Allowed.^ 
1. Mention any one property of the centre of gravity of a body. 
A triangular piece of card-board is of uniform density ; where is 
its centre of gravity situated ? 
2. Draw an angle BAG of 120°, and draw a line A D such that 
B A D is an angle of 30" and C A D a right angle. A force of 200 
units acts from A to D ; find, by construction or otherwise, the com- 
ponents of the force along A B and C. 
3. ^Vhy are the power and the weight equal in a single fixed 
pulley ? 
