when he takes hold of the bottle; nor will they
injure the table upon which he is at work. This custom, trivial as it
may seem, is of advantage, as it gives an appearance of order, and of
ease, and steadiness, which are all necessary in trying chemical
experiments. The little pupil may be told, that the custom which we
have just mentioned, is the constant practice of the great chemist,
Dr. Black.

We should take care how we first use the term _salt_ in speaking to
children, lest they should acquire indistinct ideas: he should be
told, that the kind of salt which he eats is not the only salt in the
world; he may be put in mind of the kind of salts which he has,
perhaps, smelt in smelling-bottles; and he should be further told,
that there are a number of earthy, alkaline, and metallic salts, with
which he will in time become acquainted.

When an acid is put upon an alkali, or upon limestone, chalk, or
marle, a bubbling may be observed, and a noise is heard; a child
should be told, that this is called _effervescence_. After some time
the effervescence ceases, and the limestone, &c. is dissolved in the
acid. This effervescence, the child should be informed, arises from
the escape of a considerable quantity of a particular sort of air,
called fixed air, or carbonic acid gas. In the solution of the lime in
the acid, the lime and acid have an attraction for one another; but as
the present mixture has no attraction for the gas, it escapes, and in
rising, forms the bubbling or effervescence. This may be proved to a
child, by showing him, that if an acid is poured upon caustic lime
(lime which has had this gas taken from it by fire) there will be no
effervescence.

There are various other chemical experiments with which children may
amuse themselves; they may be employed in analyzing marle, or clays;
they may be provided with materials for making ink or soap. It should
be pointed out to them, that the common domestic and culinary
operations of making butter and cheese, baking, brewing, &c. are all
chemical processes. We hope the reader will not imagine, that we have
in this slight sketch pretended to point out the _best_ experiments
which can be devised for children; we have only offered a few of the
simplest which occurred to us, that parents may not, at the conclusion
of this chapter, exclaim, "What is to be done? How are we to _begin_?
What experiments are suited to children? If we knew, our children
should try them."