November, 1910.] 



397 



Oils and Fats. 



mercial oils may also turn turbid. The 

 test for total geraniol is of great import- 

 ance in judging of the purity of the. 

 oil. The joint geraniol and citronellal 

 content of the oil is determined by 

 acetylation. But this determination 

 also may be affected by certain addi- 

 tions, such as fusel oil. It is, therefore, 

 desirable to note the odour of the acetic 

 esters which are formed in the course 

 of this manipulation. Samples examin- 

 ed in this Bureau which were adultered 

 with fusel oil when acetylated, had a 

 clearly perceptible odour of amyl acetate. 

 This odour differs unmistakably from 

 those of the geraniol acetate and of 

 the isopulegol acetate formed from 

 citronejlal. 



The optical rotation, which ranges 

 from 20 to 3°, also affords a hint to the 

 purity of the oil, but this constant, of 

 course, is also liable to be influenced 

 by adulterants. 



The fractional distillation 30 cc. of oil 

 in a Ladenburg flask (comp. Gildemeister 

 and Hoffmann, The Volatile Oils, p'. 

 190), also gives valuable clues. Pure 

 Caylon Citronella oil under this treat- 

 ment, behaved as follows : — 



190 



.218 

 231 

 239 

 249 



to 218° 

 „ 231° 

 „ 239° 

 „ 249° 

 „ 264° 



5 cc. 

 5 „ 

 5 „ 

 5 „ 

 5 



decomposition 

 commences. 



In two cases where citronella oil had 

 been adulterated with camphor oil and 

 fusel oil, the first indication thereof in 

 the testing process was that consider- 

 able proportions passed over below 

 190°. In the fractional distillation of 

 100 g. of oil part of the fraction was 

 separated. It had the unmistakable 

 odour and approximately the b. p., of 

 amyl alcohol. Prom the factions with 

 the higher b. p. a sufficient quantity of 

 camphor was separated to make it posi- 

 tively identifiable by its m.p. and that of 

 its semicarbazide. 



For the rest, it must be left to the 

 chemist concerned to test to the special 

 requirements of the case. 



The Pejumery and Essential Oil Re- 

 cord, a periodical which has recently 

 been started by J. O. Umney, contains a 

 short criticism of the solubility test for 

 citronella oil which was introduced by 

 us (Schimmel's Test). The criticism chief- 

 ly amounts to a suggestion for the im- 

 provement of our test by adding 'to it 

 the requirement of a minimum content 

 of geraniol (00%), 



The point of view expressed in this 

 criticism is quite in accord with our 

 opinion that the content of total geraniol 

 is the first factor in determining the 

 value of citronella oil. Besides Umney 

 and Parry and Bennet made similar 

 proposals years ago, their demand, at 

 the time, being for a minimum of 58% of 

 total geraniol. There would therefore 

 scarcely appear to be differences of 

 opinion with regard to the justification 

 for such a demand ; on the contrary, the 

 desire to combat more energetically than 

 heretofore the malpractices of sophisti- 

 cators, by setting up more stringent 

 tests, will express itself with increasing 

 keeness as time goes on. 



For this reason we proposed, now seve- 

 ral years ago, a more stringent form of 

 " Schimmel's Test," "Raised Schimmel's 

 Test," as follows :— 



"Citronella oil, to which has been 

 added 5% of Russian petroleum, should 

 give a clear solution at 20°C. with 1 to 2 

 volumes of 80% alcohol. This solution, 

 even after the addition of ten volumes 

 of the solvent, should remain clear or at 

 most show a feeble opalescence. In any 

 case, even after a considerable time has 

 elapsed, no drops of oil should separate 

 out." 



We are certain that if this more strin- 

 gent or "raised" form of our test had 

 been generally applied in commerce, it 

 would soon have been followed by a 

 considerable general improvement in the 

 quality of the oil. Unfortunately the 

 test has not been so applied, possibly 

 because it was feared that, if it were, 

 many pure oils would be excluded, seeing 

 that it was occasionally asserted that 

 pure oils sometimes failed to stand even 

 the ordinary Schimmel's Test. This 

 assertion is undoubtedly without foun- 

 dation, nor is it to be feared that pure 

 oils of normal condition would be unable 

 to stand the severer test ; in fact, not a 

 single valid reason can be adduced for 

 such a contention. In our own investi- 

 gations we have always found that oils 

 of really good quality do stand the more 

 stringent form of examination, and we, 

 therefore, now once more urge the intro- 

 duction of this " raised" test. 



It is true, of course, that a solubility 

 test of this kind has only a restricted 

 value, and can only afford general data 

 as to the quality of an oil, but it has 

 this advantage, that it can be applied 

 easily by any person without special 

 technical knowledge. 



Altogether different conditions would 

 arise if the geraniol determination, 

 which is of incomparably greater impor- 

 tance in the estimation of citronella oil, 



