184 REPORTS ON THE STATE OF SCIENCE.—1917. 
Simple experiments follow on the vapour pressure of water and of methylated 
spirit at different temperatures. Conditions determining evaporation of water 
are discussed, and the application of this to everyday life (drying of clothes, &c.). 
(f) Other Physical Properties of the Air.—Air is seen to possess weight. 
Air is seen to expand when heated and contract when cooled. Its density is 
roughly determined. 
II. Srconp YER. 
Elementary Chemistry. 
The ection of air on a variety of common substances, suggested by the 
class, is examined, the balance being used. Iron—having shown an increase 
in weight—is left to rust in an enclosed space. The air is thus seen to consist 
of at least two gases—active and inactive, so far as burning and rusting are 
concerned—called oxygen and nitrogen. 
A candle, phosphorus, and other combustible substances are burned in an 
enclosed space and observations recorded. Increase in weight of phosphorus is 
discovered on burning it in a tube plugged with asbestos. 
Phosphorus burned in a closed vessel shows no change in weight until the 
vessel is opened. Zhe Law of the Conservation of Matter is thus illustrated. 
Various metals are heated in the air, and observations recorded. The pro- 
cesses of rusting and burning are compared, and a definite statement of the 
composition of air is arrived at; also a first insight into the differences between 
mixtures and compounds. 
Two oxides easily decomposed by heat (red lead and mercury oxide) are 
examined; and oxyyen tested for. Potassium chlorate is also found to yield 
oxygen on heating, and, with manganese dioxide, is used in the preparation of 
the gas. 
Various metals and non-metals are burned in the oxygen prepared, and, 
when possible, the oxides are dissolved and their solutions tested with litmus. 
Thus a chemical distinction between metals and non-metals is arrived at. 
The terms Element, Compound, Mixture are discussed. 
The work of Priestley and Lavoisier is briefly described, together with an 
outline of the development of theories relating to combustion. 
The properties of Acids are next examined, especially their corrosive action 
on metals (suggested by the known effect of vinegar on a steel knife). A 
new explosive gas (Hydrogen) is discovered; and green vitriol and white 
vitriol are prepared and examined. A chemical change is seen to have taken 
place when the metal dissolved in acid. Heat was evolved. Hydrogen is 
prepared and its properties examined. The formation of a mist after 
exploding or burning the gas suggests that its oxide is a liquid, and an 
apparatus is set up for collecting hydrogen oxide. Some of the physical and 
chemical properties of the liquid so made are examined and compared with 
those of the only other known liquid which is colourless, tasteless, odourless, 
Pan ens The oxide of hydrogen is thus proved to be water (synthetical 
method). 
By using sodium, potassium, magnesium, and other metals with water or 
steam, the chemical composition of water is further confirmed, and the alkaline 
hydroxides are met with again. 
Water is also analysed by the use of an electric current, and the volume 
relationship of the gases composing it is established. 
III. Turrp Year. 
Elementary Physics and Chemistry. 
The various physical changes undergone by water under the influence of 
heat are observed, and some of the laws of heat thus taught incidentally. 
Other substances (liquids, gases, metals, and glass) are found to expand 
with heat. : 
Methylated spirit is found to expand more than water for the same amount 
of heat. The construction of a 7'hermometer is explained, and scales of tem- 
eee are compared. Convection is found to take place in air as well as in 
water. 4 
