ON TEACHING CHEMISTRY. 307 
_ stuff with its constituents—lime and chalk-gas. The chalk studies, in 
fact, should serve to incite the student’s curiosity, and should lead to 
further inquiries being undertaken as to the composition of other sub- 
stances and the characters of their constituents, and as to the nature of 
other changes ; and with regard to the method of undertaking inquiries 
into the composition of other substances, the important results obtained in 
the case of chalk by studying the changes which it undergoes would 
serve to illustrate the importance of studying change as a means of 
determining composition. 
It cannot be denied that only well-informed, thoughtful teachers could 
give useful instruction in accordance with the foregoing schemes ; but this 
is scarcely an objection. The amount of special training required to carry 
out the experimental portion would not, however, be great ; and there is 
no reason why such instruction should not be given in schools where there 
is no special science teacher engaged—although the services of such a 
teacher would undoubtedly be necessary if instruction in accordance with 
the more complete scheme embodied in the report presented last year by 
the Committee were carried out in its entirety. 
The suggestion that probably it will be found advantageous at least 
in the earlier stages, rather than disadvantageous, to devote but a short 
time during any one lesson to actual experimental work (cf. page. 300) 
would be realised in practice if the experimental science lesson were 
associated with the measurement or practical arithmetic and drawing 
lessons ; and it is difficult to imagine that this is not possible. Suppose 
a set of twenty-four pupils to be at the disposal of a teacher during an 
entire morning or afternoon in a room of sufficient size, properly appointed, 
and that they are set to work to carry out the experiments with chalk, 
described on page 304. Several—say six—might be told off to weigh out 
in platinum dishes the necessary quantities of whitening, and having then 
placed the dishes on Fletcher burners or in a muffle, they would return 
to their places ; at the end of an hour they would remove the dishes, and 
after leaving them during ten minutes to cool would weigh them. To 
determine whether any change took place on further heating, they would 
reheat the dishes during say half an hour, at the expiration of which time 
they would, as soon as the dishes were cool, weigh them again. As soon 
as the first set of six had weighed out the chalk, a second set of six 
might be set to work in a precisely similar way if the necessary apparatus 
were available, or if not at some other exercise involving the use of the 
balance. 
The nature of the experiments which each set were engaged in per- 
forming should be made known to the whole class, and all the data should 
be written up on a blackboard. Each pupil should write out an account 
of the experiments and of the results; opportunity would thus be given 
to compare the results of the six or twelve separate experiments. At the 
next lesson the two remaining sets of the class would carry out the same 
experiments. Hach pupil would thus have the advantage of performing 
one or other of the experiments, and of knowing what results had been 
obtained by a number of fellow-students. If necessary, two pupils might 
be set to perform one experiment, care being taken that they took equal 
parts in it; and thus the whole class of twenty-four might complete the 
experiment or experiments in a lesson. 
Those of the class who at any time were not actually engaged in 
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