e may be dissolved in water, and a
solution of silver nitrate containing an accurately known amount of
the silver salt in each cubic centimeter may be cautiously added from
a measuring device called a burette until precipitation is complete,
when the amount of chlorine may be calculated from the number of cubic
centimeters of the silver nitrate solution involved in the reaction.
This is a !volumetric! process, and is equivalent to weighing without
the use of a balance.

Volumetric methods are generally more rapid, require less apparatus,
and are frequently capable of greater accuracy than gravimetric
methods. They are particularly useful when many determinations of the
same sort are required.

In !colorimetric! analyses the substance to be determined is converted
into some compound which imparts to its solutions a distinct color,
the intensity of which must vary in direct proportion to the amount of
the compound in the solution. Such solutions are compared with respect
to depth of color with standard solutions containing known amounts of
the colored compound, or of other similar color-producing substance
which has been found acceptable as a color standard. Colorimetric
methods are, in general, restricted to the determinations of very
small quantities, since only in dilute solutions are accurate
comparisons of color possible.

GENERAL DIRECTIONS

The following paragraphs should be read carefully and thoughtfully. A
prime essential for success as an analyst is attention to details and
the avoidance of all conditions which could destroy, or even lessen,
confidence in the analyses when completed. The suggestions here given
are the outcome of much experience, and their adoption will tend to
insure permanently work of a high grade, while neglect of them will
often lead to disappointment and loss of time.

ACCURACY AND ECONOMY OF TIME

The fundamental conception of quantitative analysis implies a
necessity for all possible care in guarding against loss of material
or the introduction of foreign matter. The laboratory desk, and all
apparatus, should be scrupulously neat and clean at all times. A
sponge should always be ready at hand, and desk and filter-stands
should be kept dry and in good order. Funnels should never be allowed
to drip upon the base of the stand. Glassware should always be
wiped with a clean, lintless towel just before use. All filters and
solutions should be covered to protect them from dust