SCIENCE IN SECONDARY SCHOOLS. 153 
taken here. It is important that typical instances of the overthrow of a 
generally accepted theory, as well as the work of some of the great pioneers, 
should be familiar. The elementary chemistry affords excellent material for 
this, as well as for experimental investigation. For example, in the considera- 
tion of combustion and the phlogistic theory, let the boys perform the six 
following experiments : 
1. Does magnesium really lose weight when burnt? Gain in weight may 
be due to crucible, therefore 
2. Does crucible gain in weight? Perhaps the air is concerned in the 
increase, therefore 
3. Burn phosphorus in bell-jar over water. One-fifth of air active; rest, 
inactive. What has become of the phosphorus and the active constituent ? 
4. Test water with litmus. Dissolve some phosphorus pentoxide in water 
and add litmus. 
5. Burn phosphorus in a weighed round-bottomed flask with stopper and 
valve. (a) Heat has no weight, (b) conservation of mass, (c) gain in weight 
on opening valve shows that air has been used. 
6. Burn candle and catch products; determine gain in weight. 
7. Demonstration with oxygen and nitrogen to show properties of active and 
inactive constituents. 
8. Lecture on history and overthrow of phlogistic theory. 
The study of the atmosphere and the chemistry of daily life should form 
the basis of the whole chemical course in this general science. In connexion 
with flame, the simpler hydrocarbons and their combustion should be dealt 
with, and the artificial distinction of ‘organic’ chemistry should not preclude 
the average boy from dealing with the petroleum industry, coal-tar products, 
benzene, phenol, toluene, aniline dyes and mordants, sugar, alcohol and its 
uses, oils, fats, soaps and glycerine, nitroglycerine, and other explosives. 
The subject of heat probably provides the ideal experimental investigation 
in heat quantity—e.g. : 
1. Heat 500 grammes and 1,000 grammes of water over a steady flame; plot 
graph of time and temperature for each. 
Mix 500 grammes of hot water with 500 grammes of cold water. 
Mix 500 grammes of hot water with 1,000 grammes of cold water. 
Mix 1,000 grammes of various cold metals with 500 grammes of hot water. 
. Mix 100 grammes of hot water with 200 grammes of cold mercury. 
Make a cooling curve for, say, phenol. 
Heat ice steadily until the water formed boils—make a temperature- 
time curve. 
8. More accurate determination of specific heat and latent heat. 
The rest of the work should be associated with practical applications as much 
as possible. Out of the small total time available for science, it is an unjustifi- 
able waste to devote part to filling and sealing thermometers, coefficients of 
expansion, &c., beloved of the text-book and the examiner. All of this type 
of work is very necessary for those who are going to continue the study of 
science, but perfectly useless for that majority which will not do so. Men of 
science are prepared to use a watch without having made one. Why should 
not the ‘general science’ pupil use a thermometer without first making! it? 
With the saving of time thus effected, there is plenty available for work which 
really interests them, such as heat values of fuels, heat and work, work and 
power, horse-power, B.H.P. of an engine, steam-engine, energy losses, I.H.P. 
efliciency, and so on. 
In the Light course the simplest treatment of rectilinear propagations, candle- 
power, intensity, photometers, plane mirrors, laws of reflection and refraction, 
images, internal reflection, and dispersions will allow the pupil to deal with 
what he ‘wants to know about ’—viz., searchlights, prisms, lenses, the eye, 
spectaclés, magnifying glasses, telescopes, microscopes, rainbows, the spectrum, 
and fluorescence. 
In the subject of sound, waves and frequency are practically all the average 
boy requires in addition to the ear, Doppler effect, siren, gramophones, and 
Claxon horn. In all these he is interested. 
Nop WN 
