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



whilst linseed assumes a much brighter yellow coloui', and re- 

 mains fluid. India nut oil is characterized by giving a white 

 mass, becoming solid in five minutes after the addition of the 

 alkali^ which is also the case with gallipoli and pale rape, to the 

 exclusion of the other oils which I'emain fluid. 



Although it is probable that the reason why some of the oils, 

 on the application of this reagent, acquire a mucilaginous appear- 

 ance whilst others become stringy or fibrous, is due to the greater 

 or less facility with which they are saponified, still I regret that 

 I have not had the time to examine this point carefully. 



Action of diluted Sulphuric Acid on Oils. 



As different strengths of this acid have distinct reactions on 

 the oils I had at my disposal, and as they may be employed to 

 discover some known commercial adulterations, I shall discuss 

 separately each series of reactions. 



Sulphuric Acid of spec. grav. 1'475. — The mode of applying 

 this acid consists in agitating one vol. with five vols, of oil until 

 complete admixture, and then allowing the whole to stand for fif- 

 teen minutes, when the appearance is taken as the test reaction. 



Vegetable. Fish. Animal. Vegetable. 



Lard. . dirty.; India nut. Sperm \ light Neat's- / yellow Olive 1 „rppn 



Pale rapeseed. Seal /red. foot I 'tinge. Gallipoli .. ^ ^fj'^" 



Poppy. Cod liver. . purple. Sesame . . J ° ' 



Castor. Ijnseed . . green. 



„ J 1 intense 



Hempseed | ^^^^_ 



French nut. . brownish. 



The most striking reactions in this table are those presented 

 by hempseed and linseed ; for the green coloration which they 

 acquire is such, that if they were used to adulterate any of the 

 other oils to the amount of 10 per cent., their presence would 

 be indicated by the distinct green tinge they would communicate 

 to the others. The red colour assumed by the fish oils with this 

 test are also sufficiently marked to enable us to detect them in 

 the proportion of one part in one hundred of any other oil ; and 

 it is at the point of contact of the oil with the acid, on their 

 being allowed to separate by standing, that the colour is princi- 

 pally to be noticed. 



Sulphuric Acid of spec. grav. 1'530. — Having obtained by the 

 application of the preceding acid a certain number of charac- 

 teristic reactions, I was induced to try the influence of a stronger 

 one, and I therefore agitated one vol. of it with five vols, of oil, 

 and allowed the mixture to stand five minutes. 



