r of any foreign matter
becoming mixed with the substance pulverized in it. It should be
cleaned after use with pumice stone. Steel mortars are very useful for
the pulverization of hard bodies; but for all those substances which
require great care in their analysis, and which can be obtained in
very minute quantity, the agate mortar alone should be used.

A _hammer_ made of steel is necessary. This should have the edge
square.

A small _anvil_, polished on the surface, is also required. It is
frequently used to test the malleability of metals.

A _knife_, for the purpose of ascertaining the hardness of minerals.

The student should also be provided with several three-edged files,
and likewise with some flat ones.

A _microscope_, an instrument with two lenses, or with such a
combination of lenses, that they may be used double or single, is
frequently necessary for the examination of blowpipe experiments, or
the reaction of the fluxes. Common lenses, howsoever cheap they may
be, are certainly not recommended. A microscope with achromatic lenses
can now be purchased so cheap that there is no longer any necessity of
procuring one with the common lens. Besides, there is no reliability
whatever to be placed in the revelations of the common lens; while on
the contrary, the deceptive appearances which minute objects assume
beneath such lenses are more injurious than otherwise. A small cheap
set of magnifying glasses are all that is required for the purpose of
blowpipe analysis, Fig. 12.

[Illustration: Fig. 12.]

A small _magnet_ should be kept on hand, for the purpose of testing
reduced metals.

_Nippers_, for the purpose of breaking off pieces of minerals for
analysis, without injuring the entire piece, are indispensable, Fig
13.

[Illustration: Fig. 13.]

A pair of _scissors_ is required to trim the wick of the and for the
trimming of the edge of platinum foil.

A small _spatula_ should be kept for the purpose of mixing substances
with fluxes.

THE REAGENTS.

Those substances which possess the property of acting upon other
substances, in such a characteristic manner that they can be
recognized, either by their color, or by their effervescence, or by
the peculiar precipitation produced, are termed _reagents_. The
phenomena thus produced is termed _reaction_. We use those reagents,
or _tests_, for the purpose of ascertaining the presence or the
absence of certain substances, through the peculiar phe