32 PEDALINEJE. 



of the oil with one of glacial acetic acid. If a cold mixture 

 of equal weights of sulphuric and nitric acids is added in like 

 volume, the acetic solution acquires a greenish yellow hue. 

 The same experiment being made with spirit of wine substi- 

 tuted for acetic acid, the mixture assumes a blue colour, quickly 

 changing to greenish yellow* The oil itself being gently 

 shaken with sulphuric and nitric acids takes a fine green hue, 

 as shown in 1852 by Behrens, who at the same time pointed 

 out that no other oil exhibits this reaction. It takes place 

 even with the bleached and perfectly colourless oil. Sesame oil 

 added to other oils, if to a larger extent than 10 per cent., may 

 be recognised by this test. The reaction ought to be observed 

 with small quantities, say 1 gram, of the oil and 1 gram, of 

 the acid mixture previously cooled.'* 



J, F. Tocher recommends the use of hydrochloric acid with a 

 little pyrogallol for detecting the presence of Sesame oil; 

 14 parts of the acid and 1 part of pyrogallol are to be placed 

 with an equal proportion of the oil to be tested in a test tube, 

 which is corked and well shaken. The tube is then to be allowed 

 to stand for five minutes, when, the upper layer of oil having 

 been removed by a pipette, the acid solution is boiled for five 

 minutes. If Sesame oil is present, it will show a purple colour 

 when viewed by transmitted Kght, and a blue colour by reflect- 

 ed light ; the latter colour is best observed when the fluid is 

 poured into a porcelain capsule. After a time a slight blue 

 precij)itate is thrown down. Olive oil tested with this re-agent 

 afforded a faint yellowish colour, almond, groundnut and rape 

 oils no colour, and cotton-seed oil a very pale red. An admix- 

 ture of 1 to 2 per cent, of Sesame oil with olive oil may thus be 

 detected. 



The substance obtained bv FliinkiVpr mi rTimV^io- Spsame oil 



a€i 



to be 



volumes of oil. Aft^r removal 



gelatinous r^^idue was left, which, upon agitation with weak 



►task sol 



which, after being well washed with distilled 



twelve hours, afforded a deposit, 



