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146 QUANTITATIVE AGRICULTURAL ANALYSIS

Crude Fat or Ether Extract.—The nature of the material
obtained by extracting feeds with ether varies according to the
nature of the feed. Grains and otheit seeds yield nearly pure
fat, while in fibrous materials many compounds, such as waxes,
resins and chlorophyl, also are extracted by the ether.

FIG. 41.—Apparatus for extraction by volatile solvents.
When there is present in the feed a considerable amount of
soluble carbohydrates, such as starch or sugars, and a relatively
small amount of fat, as in wheat and rye, it is best to dissolve
out these substances with water before attempting to extract
the fat. It is quite essential that samples to be extracted be
thoroughly dried and that the ether be free from alcohol and