Mr. F. C. Calvert on the Adulteration of Oils. 105 



Light colorations. 



Dark colorations 



Animal. 



Vegetable. 



Vegetable. 



Lard . 



/dirty 

 \ white, 

 f brownish 

 Neats'foot^ dirty 

 L white. 



Sesame 



Olive /greenish. 



I white, 

 f greenish 

 < dirty 

 L white. 



India nut. ■ . . 1 j- »„ 



Pale rapeseed . . pink. 



Sperm.... I , 



Seal /'^"• 



Cod liver . . pm-jjle. 



Gallipoli . . . 

 French nut . 



Hempseed 

 Linseed . . 



}gray. 



{intense 

 green, 

 f dirty 

 I green. 



As hempseed, linseed, fish, gallipoli, and French nut are the 

 only oils that assume with the above reagent decided colorations, 

 they can be discovered in any of the others. 



Sulphuric Acid of spec. grav. 1'635. — This acid was used in a 

 similar manner to those above, and the coloration noted after 

 two minutes. 



Distinctly coloured. 



Vegetable. 



Sperm 

 Seal.... > 

 Cod liver J 



Neat'sfoot. . brown. 



"bro"^. ^""^ "S''^ ^'■'"■™- 



Olive (light) "1 



Hempseed (intense) ^ green. 



Linseed J 



Gallipoli 



Pale rapeseed I , 



French nut >^"™- 



India nut (light). 



I wish to draw especial attention to this acid, as it gives di- 

 stinct and widely differing reactions from those of the former 

 acids. The colorations produced by sulphuric acid, spec. grav. 

 1'635, are so marked that they may be consulted with great 

 advantage in many cases of adulteration; for example, I have 

 been able to detect, distinctly, 10 per cent, of rapeseed in olive 

 oil, of lard in poppy, of French nut in olive, of fish oil in neat's- 

 foot. 



I was much struck by the gradual increase of coloration 

 assumed by some of the oils when treated by sulphuric acid of 

 different strengths. Thus I found that gallipoli, Avhich was 

 white with No. 1 sulphuric acid, becomes brown with No. 3 ; 

 pale rape, which was white with No. 1 acid, gives a pink colour 

 with No. 2, and a brown with No. 3 ; whilst neat'sfoot is of a 

 light yellow with No. 1, but becomes brown with No. 3. These 

 results therefore clearly show the decomposing action of sulphuric 

 acid on oils, and that an acid of spec. grav. 1*635 is the maximum 

 strength that can be used, for nearly all the oils beginning to 

 carbonize, their distinct colorations are destroyed. 



Action of Nitric Acid of different strengths on Oils. 



Owing to the reasons given in the first part of this memoir, I 

 employed diluted acid and obtained a series of reactions, some 

 of which will, I hope, prove useful in some special cases of adul- 



Phil. Mag. S. 4. Vol. 7. No. 4-3. Feb. 1854. I 



