ON SCIENCE IN SCHOOL CERTIFICATE EXAMINATIONS. 479 



The other subject courees are more familiar. It is only necessary to direct 

 attention to the special human features of the work and to give one or two 

 examples of experimental investigations. Thus, the hydrostatics can be based 

 on a machine and involve consideration of other familiar applications in addi- 

 tion to those already mentioned in A, such as pulleys, jacks, balloons, siphons, 

 and turbines. If the mathematical work of the school does not comprise them, 

 then falling bodies, Newton, &c. , Galileo's disproof of Aristotle should be 

 taken here. It is important that typical instances of the overthro-w 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, ae 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 

 bo 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. 



2. Mix 500 grammes of hot water with 500 grammes of cold water. 



.T. Mix 500 grammes of hot water with ] ,000 grammes of cold water. 



4. Mix 1,000 grammes of various cold metals with 500 grammes of hot water. 



5. Mix 100 grammes of hot water with 200 grammes of cold mercury. 



6. !Make a cooling curve for, say, phenol. 



7. 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. 

 efficiency, and so on. 



In the course on light the simplest treatment of rectilinear propagation.s, candle- 

 power, intensity, photometers, plane mirrors, laws of reflection and refraction, 



