— 70 — 



which is the cause of contradictory analytical results. But the separate 

 determination of the acid-value has the additional advantage that it makes 

 it possible to detect the addition of a deliberately added acid, as has 

 occurred for instance, in the case of lavender oil. It is urgently to be 

 desired that it may become the general practice in analyses to indicate 

 separately the acid- and the ester-value so that it may be clear at a glance 

 on what basis the ester-content has been calculated and to what possible 

 discrepancies may be due. 



On the detection of foreign esters in bergamot oil, see p. 149. 



Lemon Oil. Parry again combats Chace's 1 ) opinion that every lemon 

 oil is adulterated with oil of turpentine if pinene can be detected in it under 

 certain definite experimental conditions. Parry 2 ) took 10 samples of lemon 

 oil, which had been found pure when examined by other tests, and tested 

 them for pinene by Chace's method, with the result that only four of them 

 were found to be free from pinene, while in two cases the result was 

 doubtful and in the other four positive. Arguing from these results, Parry 

 regards Chace's test as quite useless, because the presence of small pro- 

 portions of pinene in oil of lemon is no proof that turpentine oil has been 

 added, and because, when turpentine oil is really present, it can be de- 

 tected much more easily by the usual methods of examination. Parry 

 again lays stress upon the fact that limonene nitrosochloride occurs in 

 various crystallising forms and that this may give rise to confusion with 

 pinene nitrosochloride. He also points out once more that a whole series 

 of lemon oils which at the time were pronounced as adulterated by Chace, 

 merely on account of their pinene-content, really gave constants approxi- 

 mating more closely to the normal than did many authentic oils collected 

 by Chace which had given no pinene-reaction. All this, in Parry's opinion, 

 is sufficient reason for doubting the reliability of Chace's method. 



Orange Oil. A. H. Bennett 3 ), of Catania, Sicily, in an article on the citrus 

 oils states that according to his experience of many years the rotation of sweet 

 orange oil (at 15,5°) lies between 97 and 99° (= + 95°55' to 97°55' at 20°), 

 and mostly, in fact, between 98 and 99°. It is doubtful if genuine oil is 

 ever quite so low as 97° and a lower rotation indicates positively that 

 the oil has been adulterated with bitter orange oil. According to Bennett 

 the sp. gr. lies between 0,848 and 0,850. 



For bitter orange oil, Bennett states the limits of value as follows: 

 d 16l5 o 0,852 to 0,854; « Di5( 5o + 91 to +94° (=89°55' to 92°55' at 20°). 



Parry 4 ) in a note commenting upon Bennett's statements, goes so far 

 as to assert that in the case of bitter orange oil a rotation of less than 

 92° indicates the presence of lemon oil terpenes. 



*) Comp. Report November 1908, 63; April 1910, 64. 

 2 ) Chemist and Druggist 78 (1911), 159. 

 8 ) Perfum. and Essent. Oil Record 1 (1910), 230. 

 4 ) Ibidem 251. 



