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



teratioii^ and interesting as showing the influence of gradual 

 oxidation on oils. 



Nitric Acid of spec. grav. 1*180. — One vol. of this acid was 

 agitated with five vols, of oil, and the appearance, after standing 

 five minutes, is described in the follomng table : — 



Not coloured. Coloured. 



( ^ , , ^ , 



Fish. Animal. %'egetable. Fish. Animal. ^'egetable. 



Cod liver. Lard. India nut. ^ /slight Neat's- 1 light Olive |^green- 



Pale rapeseed. 'P '"X vellow. foot J yellow. Gallipoli . . J ish. 



Poppy. Seal. . . . pmk, Hemnseed i'^''^^ 



Castor. Mempseea. . <^_ ^^^^, 



French nut "l 

 Sesame I ]i 



(orange) f-' 

 Linseed . . J 



This test is sufficiently delicate to detect, distinctly, 10 per cent, 

 of heinpseed in linseed, as the latter assumes the greenish hue 

 so characteristic of the former. Although olive acquires also a 

 green colour, still its shade is such that it is easily distinguished 

 from that of hempseed. 



Nitric Acid of spec. grav. 1 'SSO. — I employed this stronger 

 acid with the view of increasing the colorations of certain oils, 

 so as to render them sufficiently marked to ascertain the pre- 

 sence of these oils when mixed with others. The proportions 

 used and the time of contact were the same as above. 



Not coloured. Coloured. 



' * \ < " % 



Fish. Animal. Vegetable. Fish. Animal. Vegetable. 



Cod liver. Lard. India nut. Snerm •[ ''^'^'' Neat's- 1 light Poppy(yellow) "1 



Pale rapeseed. P \ yellow. foot J yellow. French nut .. >recl. 



Castor. o , r light Sesame J 



*''"•• 1 red. Olive .. \ . ■ 



Gallipoli }e'«^""'»' 

 C green- 



HempseedJ '^*>Jy 



I. brown. 

 Linseed yellow. 



The chief characters in the above table are those presented by 

 hempseed, sesame, French nut, poppy, and seal oil ; and they 

 are such that not only may they be employed to distinguish 

 them from each other, but are sufficiently delicate to detect their 

 presence when mixed with other oils in the proportion of 10 per cent. 



Nitric Acid of spec. grav. 1"330. — One vol. of this acid was 

 mixed with five vols, of oil, and remained in contact five minutes. 



Not coloured. Coloured. 



Vegetable. Fish. Animal. Vegetable. 



India nut. Sperm . . "I . . r very slight Poppy T 



Pale rapeseed. Seal ^red. ■■■■^ vellow. French nut (dark) Vred. 



Castor. Cod liver J Neats'foot. . light brown. Kesame (dark) ..J 



Olive "I green- 



Oallipoli J ish. 



Hempaeed {^ZZ":^' 



^-«i {^nTb~r- 



