try it.

[Illustration: FIG. 26.]

~Measuring Liquids.~--For coarse work, such as measuring acids for
dissolving ores, graduated glasses similar to those used by druggists
may be used. It is well to have two sizes--a smaller graduated into
divisions of 5 c.c. (fig. 26), and a larger with divisions equal to 10
c.c. No measurement of importance should be made in a vessel of this
kind, as a slight variation in level causes a serious error.

~Graduated flasks~ must be used when anything has to be made up to a
definite bulk, or when a fixed volume has to be collected. If, for
example, a certain weight of substance has to be dissolved and diluted
to a litre, or if the first 50 c.c. of a distillate has to be collected,
a flask should be used. Each flask is graduated for one particular
quantity; the most useful sizes are 1000 c.c., 500 c.c., 200 c.c., 100
c.c., and 50 c.c. The mark should be in the narrowest part of the neck,
and should be tangential to the curved surface of the liquid when the
flask _contains_ the exact volume specified. The level of a curved
surface of liquid is at first somewhat difficult to read: the beginner
is in doubt whether the surface should be taken at A, B, or C (fig. 27).
It is best to take the lowest reading C. In some lights it is difficult
to find this; in such cases a piece of white paper or card held behind
and a little below, so as to throw light up and against the curved
surface, will render it clear. In reading, one should look neither up at
nor down upon the surface, but the eye should be on the same level with
it. It must be kept in mind that flasks _contain_ the quantity
specified, but deliver less than this by the amount remaining in them
and damping the sides. If it is desired to transfer the contents say of