Mr. F. C. Calvert on the Adulteration of Oils. 107 



The colorations here described are very marked, and can be • 

 employed with advantage to discover several well-known cases of 

 adulteration ; for instance, if 10 per cent, of sesame, or French 

 nut, exists in olive ; as for poppy with the same oil, the tinge 

 produced not being so intense as the preceding ones, so small 

 an adulteration cannot be detected with certainty ; and admitting 

 any doubt remained in the mind of the operator as to whether 

 the adulterating oil was sesame, French nut, or poppy, he would 

 be able to decide by applying the test described in the next table, 

 where he will find that French nut oil gives a fibrous semi- 

 saponified mass ; sesame a fluid one, with a red liquor beneath ; 

 and poppy also a fluid mass, but floating in a colourless liquor. 



The successive applications of nitric acid of spec. grav. 1*330, 

 and of caustic soda of spec. grav. 1'340, can also be successfully 

 applied to detect the following very frequent cases of adultera- 

 tion : — 



1st. That of gallipoli with fish oils, as gallipoli assumes no 

 distinct colour with the acid, and gives with soda a mass of 

 fibrous consistency, whilst fish oils are coloured red and become 

 mucilaginous with the alkali. 



2nd. That of castor with poppy oil, as the former acquires a 

 reddish tinge, and the mass with the alkali loses much of its 

 fibrous appearance. 



3i-d. That of rapeseed with French nut, as nitric acid im- 

 parts to the former a more or less red tinge, which on addition 

 of the alkali not only increases, but also renders moi'e fibrous 

 the semi-saponified mass. 



The colorations which divers oils assume under the influence 

 of the three above nitric acids clearly illustrate the remarks 

 made at the commencement of this paper, that the reason why 

 the chemists who preceded me in these tedious researches had 

 not arrived at satisfactory results in distinguishing oils and their 

 various adulterations, was owing to the acids they employed 

 being so concentrated that all the distinctive colorations were 

 lost, the oils becoming yellow or orange. But there is no doubt 

 tliat the above reagents will enhance the value of M. F. Boudet^s 

 process, as they afford very useful data to specify the special oils 

 mixed with olive. 



(Jauatic Soda of spec. (jruv. 1"340. — The following reactions 

 were obtained on adding ten vols, of this test-liquor to the five 

 vols, of oil which had just been acted up(m by one vol. of nitric 

 acid : — 



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