components (A) and (R), having boiling points T and 

 TI, respectively. (A) and (B) are each present to the 

 extent of 50 per cent. If (A) had no effect on (B) then 

 all of (A) would distil over before any of (B) began to 

 come over, and plotting the percentage distillate 

 against boiling points the two vertical lines AX and BY 

 would result. The break in the curve would indicate 

 a change of composition. In an actual distillation this 

 complete separation is never obtained, one component 

 affecting the boiling point of the other. The curve ob- 

 tained when an ordinary mixture is distilled is repre- 

 sented by Curve I where there is a gradual gradation 

 of the two components. A better separation is ob- 

 tained by the use of a fractionating column and such 

 separation would be represented by Curve II. In 

 general, approaching the vertical indicates a fairly 

 constant composition, a change towards the horizontal 

 indicates a rapid change of composition. Placing this 

 interpretation upon it, Curve II would represent -45 

 per cent pure (A), 10 per cent rapidly changing, mix- 

 ture, and the rest pure (B). In a like manner, the 

 curves obtained from the specific gravity and index of 

 refraction (two of the most constant properties of 

 any oil) should be considered. A rapid change of the 

 specific gravity or index of refraction indicates a rapid 

 change of composition. 



TABLE I FRACTIONATION OK SAGE OIL SHOWING PHYSICAL PROPERTIES OF 

 EACH FRACTION 



10 Over 205 



12.4 



(a) Optical constants not taken, due to formation of solid particles. 



Table I shows the fractions we obtained from oil of 

 black sage with the constants for each fraction. 



Fraction i had a pinene-like odor, Fractions 2-7 

 had a cineol odor, and the rest of the fractions a cam- 

 phoraceous odor. A small amount of solid matter 

 began to form in the condenser in Fraction 8 as the 

 200 mark was reached; this solid matter collected so 

 rapidly in Fraction 9 that the condenser had to be 

 steam-jacketed to carry on further distillation. The 

 specific gravities were determined with a pycnometer, 

 the index of refraction with a Pulfrich refractometer. 



(3) 



