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finds expression in the fractional distillation. If the English investigators 

 had been content to take account of the boiling points alone, and to 

 subject to comparative examination the amounts and constants of the 

 fractions which passed over between the same intervals of temperature, 

 they would have been able from those data to draw much more accurate 

 conclusions as to an eventual adulteration than is possible with the 

 distilling-method actually followed by them, for they merely fractionated 

 the oils in such a manner as to obtain corresponding fractions of equal 

 amount, independent of the boiling-temperature. That this was the case 

 is directly evident from Jensen's statements. 



Although we were clear from the first that the conclusions which 

 Parry, Umney and Jensen have drawn from their investigations were 

 untenable, we felt nevertheless that it was desirable to give experimental 

 proof in support of our contention, for which reason we have carried 

 out the examination detailed, below modelled upon that of the 

 English chemists. A normal star anise oil (d 2 oo 0,9811; « D — 0°19'; sol. 

 p. + 16,5°) was split up into 5 separate fractions, at ordinary pressure, 

 with the use of a fractionating head. As in the case of Parry's tests, 

 the first fraction was 10°/o, the three following fraction 25% each, and 

 the residue 15°/<> of the sample. We next fractionated in the same manner 

 an oil deficient in anethol prepared by removing a portion of the anethol 

 from the sample of the normal oil under examination, the constants, 

 after removing anethol being: sp.gr. 0,9696 (20°), opt. rot. — 0;° 41', sol. 

 p. 10,1°. We then ascertained the constants of the separate fractions, 

 of which we tabulate the solidifying points and refractive indices below, 

 side by side with the corresponding values given by Parry. 



The agreement in behaviour of the fractions of the two normal star 

 anise oils on the one hand, and of the oil deficient in anethol and the 

 suspected oil on the other, shows plainly how impossible it is, from an 

 examination of this nature, to draw conclusions as to adulteration, and 

 how rash has been the judgment of the English chemists. If further evidence 

 were wanted we might point to the fact that the differences in the behaviour 

 on boiling between the normal oil and the oil deficient in anethol correspond 

 exactly with those observed by Jensen in his two oils. It goes without 

 saying that in our two oils also the odour of the corresponding fractions 

 differed somewhat. The fact that the suspected oil was slightly dextro- 

 rotatory also goes for nothing, for our experience shows that unquestionably 

 pure star anise oils are sometimes slightly dextrorotatory. 



However valuable may be the services fractional distillation is able, 

 under certain conditions, to render in the examination of essential oils, 

 there is no justification for attaching too great an importance to it without 

 collateral evidence, for if this were done it would be easy, as the in- 

 vestigations of Parry, Umney and Jensen show, to draw conclusions of an 

 extremely questionable character. 



