(^158) THE CHEMISTKY OF ESSENTIAL OILS
have been removed from it, and the degree of fractionation which it
has undergone, it is obvious that scientific standards for it cannot be
set up. It is frequently sold on the basis of a guaranteed specific
gravity, which gives a good indication of its general quality. The fol-
lowing may be regarded as the general types of oil to be found in com-
merce —
tuis.
(Tuis.)
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