6 BULLETIN (ioo, U. S. DEPARTMENT OF AGRICULTURE. 



chemical constants. Ether extractions were made by means of the 

 customary Soxhlet extractors, while a small laboratory hydraulic 

 press served for the cold expression of the oil. The yields of oil 

 given in all cases represent ether-extracted oils, whereas all physical 

 and chemical properties were determined upon cold-pressed oils. 



It must be borne in mind that these cold-pressed samples differ 

 from ordinary commercial raw linseed oils, being obtained under 

 entirely different conditions. The results obtained are therefore 

 comparable with each other, but not with commercial linseed oils. 



The color was carefully noted in each case. Considerable diversity 

 appeared and the colors are described as well as possible in order 

 to bring out the existing differences. 



The specific gravity and the refractive index, being affected by 

 the composition of the oils, were carefully determined. Both of 

 these constants bear a certain relationship to the composition of 

 the oil. 



Table II was prepared to show the similarities and differences 

 in yield and physical properties of the various oils examined. The 

 yield of oil and physical properties are arranged according to the 

 stations at which the several varieties of flax were grown. Each 

 Cereal Investigations number of flax grown at any station is given, 

 together with the yield of oil during the two years. This arrange- 

 ment permits a comparison of the varieties grown at each station 

 during the two successive seasons. 



By a careful study of Table II it will be seen that the samples of 

 flax bearing Cereal Investigations numbers grown at each station 

 during either of the tv o years vary considerably in yield of oil. This 

 variation is apparent at each of the stations. Since each of the 

 numbers represents a different variety, the differences in the yield of 

 oil may be attributed to the varieties. When the same variety as 

 grown at widely separated stations shows differences in yield of oil 

 it is probable that climatic and soil conditions play an important 

 part. 



In comparing the Cereal Investigations numbers of any one station 

 dining the two years, the yields of oil in many cases are distinctly 

 comparable. While not constant, a certain degree of constancy is 

 noticeable among them. 



In order to make a better comparison of the Cereal Investigations 

 numbers, not only at each station but at all the stations, the average 

 oil yields were calculated and are included in Table II. A glance 

 at the average yield of oil from the various Cereal Investigations 

 numbers discloses those producing the highest and lowest yields at 

 each station. It is noticed that Nos. 3 and 19 occupy a high position 

 with regard to oil content, while Nos. 12 and 13 are usually low. 

 The stations producing the highest and lowest oil yields are also 

 clearly indicated in Table II. 



