FERMENT OILS. 349 



biting taste. It is not very volatile. AVith iodine it forms a 

 violet solution. It dissolves sparingly in water, readily in alcohol, 

 ether, and oils fixed and volatile.* 



Ferment oil of Conium maculatum. Obtained from fresh 

 hemlock in the same manner as the above. Colourless, has a 

 peculiar odour not like that of hemlock, and a sharp, burning taste. 

 It is not poisonous. Dissolves freely in alcohol, ether, and oils 

 both fixed and volatile.f 



Ferment oil of Centaurium minus (Erythrcea Centaurium, 

 " Petite centauree "). This is perhaps the most remarkable example 

 of the generation of a true ethereal oil from a plant destitute of 

 odour. The plant is macerated in water at a slightly elevated 

 temperature; after 12 hours it ferments and gives oft' a perceptible 

 odour which is agreeable and penetrating. This increases up to 60 

 hours, and then ceases. If the fermenting vessel be connected 

 with a condenser, the whole of the oil, which is very volatile, may 

 be collected, but following the instructions given by the original 

 observer for its preparation, .«ome of the oil would be lost. They 

 are : " Macerate the fresh herb in water for 48 hours, then distil 

 as long as drops of oil pass over into the receiver, and rectify the 

 distillate." The maceration and fermentation might be allowed to 

 continue for 60 hours if connected with a condenser so that no 

 vapours escape, and after that time heat might be applied. The 

 aqueous distillate is pale-yellow with white turbidity ; it has a 

 persistent, enlivening, aromatic odour, which is not pleasant when 

 close, and irritates the eyes and nose ; its taste is extremely 

 burning, like that of creosote, but not persistent. It reddens 

 litmus, but not permanently. ;|: The oil is thin and greenish, 

 having a peculiar and agreeable odour. It is not poisonous. 

 When heated with ammonia and nitrate of silver it reduces the 

 silver to the metallic state. 



Ferment oil of Echium vulgare (the common "Viper's 

 Bugloss," a species of Boraginacccc common throughout Britain). 

 The plant in the flowering state is first macerated and fermented, 

 then distilled. The distillate is shaken up with etlier, the ether 



* Bley, Ibid., xlviii., p. 156. 



t Landerer, Repert. Pharm., xliv., p. 237. 



X Buchner, Kepert. Pharm., liii., p. 303. 



