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[ 523 ] .^ ^:,,, , i>2c 



LiAXVlU. Intelligence and Misceuaneous Articles. ^^^^^ 



ON CAROTIN. ;3r! 



ZEISE observes that the peculiar matter of the Daucus carota 

 • has not hitherto been known in a pure state ; for by the pro- 

 cess usually employed for its extraction, which consists in treating; the 

 juice coagulated by a;ther, its evaj)oration, and treating the residue 

 with alcohol or with ammonia, the carotin is obtained always com- 

 bined with a large quantity of fat oil, and the product is merely a 

 soft mass, containing crystals of carotin. M. Zeise has tried several 

 processes to obtain it in a pure state, and has succeeded by the 

 following : — • 



The expressed juice of the roots is to be diluted with four or five 

 volumes of water, and to the mixture is to be added sulphuric acid 

 diluted with ten volumes of water. A very slight addition of this 

 acid occasions the precipitation of the whole of the colouring matter 

 of the juice. The clear liquor is to be poured off, and the mass thus 

 obtained is to be washed with water ; after this it is to be boiled for 

 au hour, or an hour and a half, with a strong solution of hydrate of 

 potash : the potash saponifies the fat oil, and dissolves a residue of 

 albumen without acting upon the carotin. The carotin is to be se- 

 parated by' filtration and washed with water. 



Thus obtained, the carotin still contains a saline body, which 

 must be decomposed to prevent its admixture with the carotin in the 

 remaining operation. For this purpose, the mass diffused through 

 water and heated is to be treated with excess of dilute sulphuric 

 acid. After having again collected the carotin on a filter and well- 

 washed it, the fatty acid is to be separated by alcohol, at first diluted, 

 but eventually nearly anhydrous. By this process very little carotin 

 is dissolved. The mass is then to be dried by the water-bath. 



When perfectly free from oil, carotin is difficultly soluble in aether ; 

 but in order to complete its purification, M. Zeise has taken advan- 

 tage of a property of carotin, discovered on this occasion, which is, 

 that it is extremely soluble in sulphuret of carbon. When the well- 

 dried mass is treated with this liquid, a solution of a deep red colour 

 is obtained, which is to be separated from a grayish substance which 

 remains undissolved. After having separated nearly three-fourths 

 of the solvent by distillation, anhydrous alcohol is to be added to 

 the residue. When the mixture is left in an open capsule, the 

 carotin soon separates in the form of small, deep red-coloured cry- 

 stals. The mother-water is to be decanted, and the crystals are 

 to be washed with anhydrous alcohol on a filter, till it comes away 

 nearly colourless. The carotin is then j)crfcctly pure; and its ap- 

 pearance is somewhat similar to that of coarsely powdered cinnabar, 

 or to that of copper, reduced from the oxide by hydrogen. The cry- 

 stals are very small, and have a strongly metallic lustre. Carotin has 

 a very slight but somewhat agreeable odour ; it is heavier than water, 

 and perfectly insoluble in it ; nearly in.soluble in alcohol, and also in 

 pyroxylic spirit, when it is well-freed from oil; it i.s very shghtly 



