10 



BULLETIN 655, U. S. DEPARTMENT OF AGRICULTURE. 



mined in order to ascertain the relative rapidity with which the 

 various oils dried to the customary film characteristic of drying oils. 



The drying tests were conducted by spreading a thin film of oil 

 over ground-glass plates 2 inches square and allowing the film to dry 

 by exposure to the air, due precaution being taken to prevent the 

 accumulation of dust on the surface. The experiments were con- 

 ducted indoors at ordinary room temperature during the winter and 

 early spring months. 



Approximately the same weight (about 0.1820 gm.) of oil was 

 used in every case, the oil spreading over an area of about H square 

 inches. The glass plates with the film of oil were weighed at definite 

 intervals until no further increase in weight was observed, the time 

 of complete drying being expressed in days. The average increase 

 in the weight of all the oils varied from 12 to 14 per cent. 



Comparison of the drying tests in Table III shows that certain 

 Cereal Investigations numbers at different stations produce oils which 

 dry more rapidly or more slowly than others. 



Some stations show a close relationship among the Cereal Investi- 

 gations numbers in the time of drying during the two seasons, while 

 others show considerable variation in this respect. The effect of 

 seasonal variation upon the composition of the oils at the stations 

 is again evident. 



A study of this nature admits of two general comparisons, namely, 

 (1) a comparison of the several Cereal Investigations numbers and (2) 

 a comparison of stations with respect to the oils produced during the 

 two seasons. 



In order that the data given in Tables II and III as related to the 

 several Cereal Investigations numbers may be more readily compared, 

 the yearly and general average yield, the specific gravity, the acid 

 value, the iodin value, and the time of drying of the oils were com- 

 puted and the results assembled in Table IV. 



Table IV. — Comparison of yield, specific gravity, acid value, iodin value, and time of 

 drying of oils from the four flax varieties grown in 1914 and 1915. 





Yield of oil (per 

 cent). 



Specific gravity. 



Acid value. 



Iodin value. 



Time of drying 

 (days). 



Seed 

 sample. 



Yearly- 







Yearly 



CD 



> 





Yearly 







Yearly 



> 





Yearly 



a> 





average. 



OS . 





average. 



a . 





average. 



03 . 





average. 



CO . 





average. 



03 . 









































cj to 







C3 to 







a tt 







CO to 







a is. 







-r 



>a 







- 



S 



'O 



a 



c 



■* 



tra 



a 



S 



■* 



•ra 



o * 



a 



q 



■* 



<o 



a a 



a 



q 





» 



en 



o 



- 

 2 



a 



c-. 



a 



2 

 2 



en 



en 



o 



4 



OS 



en 



o 



3 



o 

 16.4 



o 

 16.3 



a 



16.35 



PS 



No. 3 



34. 59 



35. 65 



35.11 



0. 92S1 



0. 9297 



0. 9289 



0.972 



0.713 



0.841 



161. 3 



161.6 



161.1 



4 



No. 12.... 



32.4135.29:33.84 



3 



.'S^l .9294' .9287 3 



.975 



.754 



.861 



2 102.5 



163.4 



162.9 



1 16.1 



15. 15. 57 



3 



No. 13.... 



:>;i. 07 X',. vi X',. si 



4 



.9284 .9300 .9292 



1 



.940 



.765 



.851 



3 



100. 4 



102.0 



161. 5 



2 16. 1 



14. 7 15. 43 



2 



No. 19.... 



35. 98 36. 79 36. 42 



1 1 



1 



.9270 .9295 .9285 



4 



1.10 



.738 



.920 



1 



161.7 



159.8 



160.8 



414.3 



15. 7 15. 00 



1 



1 



The yield of oil of the several Cereal Investigations numbers grown 

 at all the stations during each season is strikingly constant. The rel- 

 ative position of each number with respect to the average yield of oil 



