16 BULLETIN 655, U. S. DEPARTMENT OE AGRICULTURE. 
be assumed that the climatic and soil conditions existing at the 
respective localities acted in conjunction in a similar manner from 
year to year in affecting the growth and development of the plant. 
The yields of oil were found to vary with the variety of flax as well 
as with the locality in which it was grown. Thus, certain Cereal In- 
vestigations numbers gave constantly high or low yields of oils during 
the two years, and certain stations yielded flax samples with con- 
stantly high or low content of oil. 
The physical properties, specific gravity, index of refraction, and 
color are apparently quite variable in many instances and are not 
so easily correlated with variety or locality. 
A direct relationship appears to exist between the drying property 
of the oils and the specific gravity, acid value, and iodin value. Oils 
combining high acidity with high specific gravity and possessing a 
relatively high iodin value invariably dried to a firm film most rap- 
idly. The relationship between the drying property and the color 
of the oils was also very marked. The lightest colored oils invari- 
ably possessed the most rapid drying properties. 
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