nts under such conditions as will insure accurate
quantitative estimations.

It is assumed that the operations of qualitative analysis are familiar
to the student, who will find that the reactions made use of in
quantitative processes are frequently the same as those employed in
qualitative analyses with respect to both precipitation and systematic
separation from interfering substances; but it should be noted that
the conditions must now be regulated with greater care, and in such
a manner as to insure the most complete separation possible. For
example, in the qualitative detection of sulphates by precipitation
as barium sulphate from acid solution it is not necessary, in most
instances, to take into account the solubility of the sulphate
in hydrochloric acid, while in the quantitative determination of
sulphates by this reaction this solubility becomes an important
consideration. The operations of qualitative analysis are, therefore,
the more accurate the nearer they are made to conform to quantitative
conditions.

The methods of quantitative analysis are subdivided, according
to their nature, into those of !gravimetric analysis, volumetric
analysis!, and !colorimetric analysis!. In !gravimetric! processes the
constituent to be determined is sometimes isolated in elementary
form, but more commonly in the form of some compound possessing a
well-established and definite composition, which can be readily and
completely separated, and weighed either directly or after ignition.
From the weight of this substance and its known composition, the
amount of the constituent in question is determined.

In !volumetric! analysis, instead of the final weighing of a definite
body, a well-defined reaction is caused to take place, wherein the
reagent is added from an apparatus so designed that the volume of the
solution employed to complete the reaction can be accurately measured.
The strength of this solution (and hence its value for the reaction
in question) is accurately known, and the volume employed serves,
therefore, as a measure of the substance acted upon. An example will
make clear the distinction between these two types of analysis.
The percentage of chlorine in a sample of sodium chloride may be
determined by dissolving a weighed amount of the chloride in water
and precipitating the chloride ions as silver chloride, which is
then separated by filtration, ignited, and weighed (a !gravimetric!
process); or the sodium chlorid