276 REPORT—1890. 
6. Explain the meaning of the term allotropy. How can plastic sulphur be 
obtained, and how is it shown to be identical with common sulphur ? 
7. What methods are commonly used to obtain solutions of (a) chlorine, 
(6) hydrogen sulphide, (c) ammonium sulphide? For what purposes are these 
solutions used ? 
8, Given metallic copper and lead, how would you obtain their several oxides? 
Describe each shortly. 
Il. 
1. Explain briefly the terms atom, atomic weight, acid, base, salt, alkali, 
precipitate, sublimate, distillate. 
2. When copper oxide is heated in hydrogen some water is formed: draw and 
describe the apparatus by which the composition of water by weight is determined 
from this fact. 
3. What is combustion? Give some account of the chemical changes which 
go on when a candle burns, or charcoal, sulphur, phosphorus, or magnesium burns 
in air. Mention some examples of combustion in other gases. 
4. When sulphuric acid is heated with salt, or with a mixture of salt and 
peroxide of manganese, gases are obtained. Give equations for the actions, and 
point out some important differences in the two gases. 
5. Mention several methods for obtaining gaseous sulphur dioxide from sulphuric 
acid, and explain how the dioxide can be converted into sulphuric acid. What 
are the chief properties of the gas? 
6. What compounds does hydrogen form with (a) bromine, (4) nitrogen, 
(c) sulphur, (d) phosphorus? Give a brief account of each, and explain how 
they are obtained. 
7. Give an account of the chemical actions, if any, which take place when 
iron, copper, mercury, or lead is heated in air, heated in nitric acid, heated in 
hydrochloric acid. 
8. Explain how caustic soda is made from common salt. 
COMMERCIAL CERTIFICATES. 
InorRGANIC CHEMISTRY. 
I 
1. Why is the red solid produced by heating clear phosphorus at 240° in a flask 
full of carbonic-acid gas considered to be an element and not a compound ? 
2. Arrange the elements hydrogen, oxygen, chlorine, sulphur, bromine, nitrogen, 
sodium, phosphorus, potassium, calcium, magnesium, zinc, mercury, iron, and 
chromium in groups, in accordance with their chemical similarities. Give reasons 
for your classification. 
3. Why do many chemists prefer to represent the combination of hydrogen 
with chlorine by the equation H,+Cl,=2HCl rather than by the simpler expres- 
sion H+Cl=HCl? 
4, How would you show by experiment that each of the following bodies 
contains hydrogen ?— 
(a) Water. | (6) Hydrochlorie acid. | (c) Ammonia. 
5. What do people mean when they speak of water being hard or soft? How 
would you distinguish a sample of hard water from one of soft water? Explain 
the difference between permanent and temporary hardness in water. 
6. What is the smallest quantity of mercury that would be required in order to 
deprive 20 litres of air (measured under standard conditions) of all its oxygen ? 
He = 200. 
L 7 whet weight of sulphur would’ be required to produce enough sulphurous 
acid to reduce 10 grams of chromium trioxide (chromic acid CrO,) to chromium 
sesquioxide (Or,0,)? [S=32; Cr=52.] 
8. Describe the method by which Cavendish determined the composition of 
water. 
