114

QUANTITATIVE AGRICULTURAL ANALYSIS

Applications.—In a number of instances the measurement of
index of refraction furnishes a means for identifying certain
materials and in some cases a quantitative estimation is made
possible, where the identity of all components in a given mixture
is known. As an example of qualitative testing may be men-

FIG. 81.—The Abb6 refractomotor.
tioned the measurement of this property in oils and fats. This
is discussed in Chap. X. The quantitative determination of
alcohols and sugars in aqueous solutions and of milk fat in milk
and the detection of added water in milk by the examination of
milk serum are familiar examples of quantitative application of
refractivity measurements. Some of these are given attention in
Chap. XL