Mr. F. C. Calvert on the Adulteration of Oils. 109 



As three oils remain nearly colourless, viz. those of poppy, 

 olive, and India nut, we are enabled to detect in them the pre- 

 sence of any of the others ; and when olive or poppy are adul- 

 terated with sesame, the green colour at first produced is 

 much more persistent than with sesame, consequently it is ne- 

 cessary that the acid and the oil suspected of containing it should 

 remain in contact for about ten minutes in order to obtain the 

 ultimate brownish-red colour of the sesame; in fact it is so 

 intense, that it may be usefully employed to detect this oil when 

 mixed with others. 



Aqua Regia. — In consequence of the results obtained with 

 nitric acid I was induced to try the action of aqua regia ; but I 

 found that when it was composed in the ordinary way of three 

 vols, of hydrochloric and one of nitric acid, the reactions produced 

 nearly coincided with the last-named acid ; I therefore prepared 

 several aqufe regife, in which I gradually increased the propor- 

 tion of hydrochloric acid, and after having tested them, I adopted 

 one composed of twenty-five volumes of hydrochloric acid of spec, 

 grav. 1-155, and one volume of nitric acid of spec. grav. 1-330, 

 and allowed them to stand about five hours, The reactions 

 described in the following table are those which took place when 

 a mixture of five vols, of oil with one vol. of aqua regia was agitated 

 and allowed to stand five minutes : — 



Not coloured. 



Animal. Vegetable. Fish. Animal. Vegetable. 



Lard. Olive. Sperm (slight) "I Neat's- 1 slight French nut .... ^ 



Gallinoli. SeaUslight). . Wellow. foot/ yellow. Sesame Uellow. 



India nut. Cod liver .... J Linseed (green- (' 



Kapeseed. ish) .... J 



Poppy. Hempseed .... green. 



Castor. 



"N^Tien the facts contained in this table are compared with the 

 preceding ones, we are struck with their uniformity, and are led 

 to infer that no marked action had taken place ; but this con- 

 clusion is en-oneous, as most of them assume a vivid and distinct 

 coloration on the addition of an alkali of spec. grav. 1-340, as 

 seen in the following table : — 



If a fibrous mags is formed. If a fluid mass is formed. 



Vegetable. Fish. Animal. Vegetable. 



, poU(yel-i Spenn..! Lard. . pink. Olive., white. 



foot / yeUow. lowishj .... Seal.... ^°"ii°^ Poppy.. -f '"''"''' 



India nut.... white. Cod liver J J""""*' '"Pl'^-l rose, 



Palcrapcseed r orange with 



(yellowish) . . J Sesame < brown liquor 



Castor pale rose. , I. beneath. 



French nut . . orange. Linseed orange. 



Hempseed ■ • { '',^J;'^„ . 



The characters presented in this table arc such that we can 



