104 



FIXED OIL, ETC. 



Stannic chloride produces the following changes in colour: 

 linseed, dirty yellow, passing to green ; sunflower, white, turning 

 brown ; poppy, greenish ; hemp, yellowish-green ; olive, bright 

 yellow ; almond, scarcely yellowish. On warming with chloride of 

 zinc linseed oil becomes green, and hemp oil assumes a fine green 

 colour, while the remainder undergo no change. Syrupy phosphoric 

 acid forms a sort of emulsion with linseed and poppy oil, but not 

 with the others. 



Warming with mercuric nitrate colours linseed oil from dark 

 green to brownish-red ; sunflower, bright yellow ; poppy and hemp 

 oil, green, turning brown ; olive, dark yellow, passing to orange 

 red ; almond, deep chrome. 



Bieber 1 used nitric acid of sp. gr. 1*4, and also a cooled mixture 

 of equal parts of cone, sulphuric and fuming nitric acid in the pro- 

 portion of 1 volume of reagent to 5 of oil. 



Hauchecorne 2 has published reactions of oils with peroxide of 

 hydrogen, but without specifying the strength of the reagent. He 

 states that on shaking 1 volume of solution of peroxide of 

 hydrogen with 4 of oil, olive assumes an apple-green ; poppy, a 

 flesh colour ; sesame", bright red ; ground-nut, greyish-yellow ; and 

 beech-nut oil, an ochre red. According to Cohne, drying oils may 

 be distinguished from non-drying by their behaviour to peroxide 

 of hydrogen. The former are said to be quickly decomposed 

 with separation of fatty acids, whilst the latter resist such 

 treatment. 



Basoletto 3 observed that sesame" oil, when shaken with an equal 

 volume of hydrochloric acid (23 to 24 per cent) containing 2 per 

 cent, of cane-sugar, assumed a reddish tinge, passing to cherry-red, 

 whilst olive oil was not coloured. On agitating with nitric acid 

 containing sugar, sesame oil was coloured cinnamon, whilst the 

 acid became yellowish-green. Cotton-seed oil turns yellow with 

 the same reagent (the acid becoming pale rose coloured), but 



1 Apotheker Zeitung, xii. 161, 1877 (Journ. Chem. Soc. xxxiv. 343). For 

 the action of nitric acid on fatty oils, see also Hauchecorne, Zeitschr. f. anal. 

 Chemie, iii. 512, 1864, where, however, the strength of the acids employed is 

 not mentioned. Langlies (ibid. ix. 534, 1870) recommends mixing nitric acid 

 specific gravity 1'4 with of its volume of water, and warming 1 part of this 

 reagent with 3 of oil in the water-bath. Sesame oil is said to yield a red mass 

 by this treatment. 



2 Zeitschr. f. anal. Chemie, ii. 442, 1863. 



3 Bulletin delia Soc. Adriatic, i. 178, 1875. 



