110 Mr. F. C. Calvert on the Adulteration of Oils. 



discover with facility 10 per cent, of a given oil in many cases of 

 adulteration; for example, poppy in rape, olive, gallipoli, and 

 India nut, as all of them assume a pale rose-colour ; but when 

 poppy is mixed with olive or castor oils, there is a decrease in 

 the consistency of the semi-saponified mass. 



By the aid of this reagent we can also ascertain the presence 

 of 10 per cent, of French nut in olive or linseed, as the semi- 

 saponified mass becomes more fluid ; and as to French nut in 

 pale rape, gallipoli and India nut, it is recognized in consequence 

 of their white mass acquiring an orange hue. With respect to 

 linseed in hempseed, it is detected, as it renders the fibrous mass 

 of the latter more mucilaginous. Sesame also gives with this 

 reagent the same characters as those which it afforded with nitric 

 acid and an alkali ; and poppy is distinguished from all other 

 oils by giving in this case a semi-saponified mass of a beautiful 

 rose colour. 



To give an idea how the tables are to be used, I shall suppose 

 a sample of rapeseed oil adulterated with one very difficult to 

 discover. I first apply the caustic alkali test, which in giving a 

 white mass proves the absence of the fish oils together with those 

 of hempseed and linseed ; and as no distinct reactions are pro- 

 duced by the oils under examination when mixed with the three 

 sulphiu'ic and nitric acids above mentioned, poppy and sesame 

 are thrown out, as they are reddened ; neat'sfoot, India nut, 

 castor, olive, and lard resting only in the scale of probability. 

 In order to discover which of these is mixed with the suspected 

 oil, I agitate a portion of it first with nitric acid of spec. grav. 

 1*330, and then with caustic soda; and their mutual actions 

 exclude neat'sfoot, India nut and castor, as the sample does not 

 give a fluid semi-saponified mass. The absence of olive is proved 

 by no green coloration being obtained on the application of 

 syrupy phosphoric acid. As to the presence of lard oil in the 

 rape, it is ascertained on caustic soda being added to the oil 

 which has been previously acted on by aqua regia, as the latter 

 gives a fibrous yellowish semi-saponified mass, whilst the former 

 yields a pink fluid one. 



In conclusion, I trust that the reagents described in this 

 paper, and the new method of applying successively two of them 

 to any pai-ticular oil, will prove useful, not only to detect the 

 numerous admixtures of oils we have noticed, but also to trace 

 and determine in a given oil the presence of any of the others 

 which we have examined ; and I give a general table of the pre- 

 ceding reactions in order to facilitate the research for any adul- 

 teration. 



Royal Institution, Manchester, 

 January 11, 1854. 



