Ixxxii Agricultural Education — Examination Papers, 1875. 
7. A line is marked on the ground by pickets A and B ; an acces- 
sible point (P) is given at a moderate distance from AB ; show how 
to determine on the ground the point where a perpendicular let fall 
from P on AB cuts that line. 
8. You are provided only with chain and pickets and have to 
survey a field with five sides, which we will suppose to be straight 
lines ; one of the sides however is cut by a wide pond so that you 
cannot chain across it ; explain by what measurements you will be 
enabled to lay down a plan of the field. 
9. A and B are two points on the boundary of a field 12 chains 
apart ; in going from A to B, when the offsets are taken to the left 
the chain is outside the field, when to the right it is inside the field. 
At the end of each chain in succession from A the offsets severally are 
as follows :— to the right 20, 30, 50, 20, 0 ; to the left 10, 15, 30, 60, 
30, 20, 0. Lay down the boundary and determine the difference 
between the areas within and without the field. 
EXAMINATION IN CHEMISTEY. 
Maximum Number of Marks, 200. Pass Number, 100. 
I. General Chemistry. 
Wednesday, April lAth, from 10 a.m. till 1 p.m. 
1. State the composition of atmospheric air. Explain how the 
presence of carbon di-oxide in the atmosphere may be detected, and 
how the proportion in which it is present may be determined. 
2. What are the relative densities of oxygen, nitrogen, water-vapour, 
and carbon di-oxide at the same temperature and pressure ? Explain, 
by reference to general laws, why the temperatiire and pressure must 
be taken into account : also why in a mixture of gases the most denso 
does not sink to the bottom. 
3. Name substances frequently met with in uatui-e and containing 
S and P respectively. State how these elements are combined in 
each case. Describe the chief characters of S and P. 
4. Describe the preparation of chlorine, sulphuretted hydrogen, 
and caustic soda, respectively, explaining the chemistry of the pro- 
cesses. Give the chemical reaction of each one of these substances 
with each of the other two. 
5. Calculate the quantity of bone-earth which 1 lb. (7000 grs.) of oil 
of vitriol will convert into soluble superphosphate. (O : S : P : Ca = 
16 : 32 : 31 : 40.) 
6. Give the chemical constitution of alumina, silica, and rusts of 
iron and copper. Under what circumstances are the first two of these 
substances soluble in water ? Explain how they can bo detected in 
solution. 
