76 BACON. 



quality and the latter are insoluble in 90 per cent alcohol. The dif- 

 ference becomes more marked on using 75 per cent alcohol, as the first 

 quality of ylaDg-3dang oil dissolves in this strength with only a faint 

 opalescence, while second quality separates in large globules; so that this 

 distinction offers an easy method of roughly judging the quality of the oil. 



Another method of value is to prej)are a 1 per cent solution of the 

 oil in alcohol and compare the odor with a similar one of an oil of known 

 qualit}^, as judgment is much more certain as to the perfuming power 

 when dilute solutions instead of the pure oils are used. One cubic 

 centimeter of each solution can then be poured on separate pieces of 

 bibulous paper, the odor being compared at the end of twelve, twenty- 

 four, or even a longer number of hours; this test gives some idea in 

 regard to the permanence of the odor. 



Pure ylang-ylang oil oJitained by distillation in vacuo leaves a residue 



of about 5 per cent and of course if fixed oils are present, this will be 



larger. Moreover, the residue from pure ylang-ylang oil has a refractive 



30° 

 index l^^j=r- of about 1.5400, whereas a product containing 5 per cent of 



30° 

 added coconut oil had an index of N-pr-=1.5000. Fatty acids can be 



detected in this residue left on distillation by heating it with fused potas- 

 sium bisulphate, for if fatty oils are present the odor of fatty acids as 

 well as a marked one of akrolein is observed. The odor of the fatty acids 

 gives the best sign of their presence in the residue, because pure ylang- 

 ylang oil upon being treated in this way gives a rather sharp odor, which, 

 however, might be mistaken for that of akrolein. If coconut oil has been 

 added to a first-grade ylang-ylang oil to the amount of 5 per cent it can 

 be detected by the odor alone, if the person making the test is familiar 

 with the oil. Petroleimi or mineral oil can be detected in ylang-ylang by 

 destroying everything but these adulterants with concentrated sulphuric 

 acid and then distilling the remainder. 



The use of any adulteration is more emphatically the height of com- 

 mercial folly for 5-lang-ylang than it is for any other essential oil, for 

 only the product of the highest quality brings a remunerative price. A 

 10 per cent increase in quantity Ijy means of adulteration may cut the 

 jDrice in two, or may resiilt in an oil which can not be sold at any price. 

 The greatest advance in the ylang-ylang oil industry will take place when 

 the distillers o-mi tlieir groves of trees and can select only ripe, yellow 

 flowers for distillation. This fact is emphasized quite strikingly by the 

 following experiment : 



Fifty-four and five-tenths kilos (120 pounds) of extra fine flowers, one-lialf 

 of whicli were perfectly j'ellow and ripe, were distilled A\ith steam in the usual 

 manner and the followinar fractions were obtained: 



