CHLOKOPHYL. 457 



blisters on the skin. Dissolves when heated for a 

 length of time with aqueous alkalies, assimilating 

 water and forming salts of cantharidic acid, C 5 H 8 3 . 

 These crystallize well, but on the addition of acids to 

 the solutions, cantharidin separates, but no cantharidic 

 acid. 



Carotin, C 18 H 24 0, together with hydrocarotin, 

 C 18 H 30 0, in carrots (Daucus carota), deposited in the 

 cells in microscopical crystals, the cause of the color of 

 the carrots. Small, reddish-brown, cubical crystals; 

 fusible at 168 ; insoluble in water, difficultly soluble 

 in alcohol. 



Carthamin, C 14 H 16 7 , the red coloring principle of 

 safflower, the dried flowers of Carthamus tinctorius. 

 After exhausting the yellow coloring principle from 

 pure safflower by means of cold water, the carthamin is 

 extracted by treating with a dilute solution of sodium 

 carbonate. The red liquid is then neutralized with 

 acetic acid, and pure cotton immersed in it, on which all 

 the carthamin is deposited. After washing with water 

 the carthamin is again extracted with a dilute solu- 

 tion of sodium carbonate, precipitated with citric acid, 

 and the beautifully crimson-colored precipitate washed 

 by decantation. Amorphous, deep-red powder, with 

 greenish iridescence; in thin layers it has a beautiful 

 green metallic lustre. Sparingly soluble in water, more 

 soluble in alcohol. Soluble in alkalies, yielding a deep 

 yellowish-red solution. Very unstable in these solu- 

 tions. Melted with potassa it yields paraoxybenzoic 

 acid and oxalic acid. 



Chlorophyl. The green color of plants is occa- 

 sioned by the presence of microscopical, green globules, 

 which float in the cells. These so-called chlorophyl- 

 globules consist of several substances, which inclose a 

 green coloring principle. The composition, as well 

 as the nature of this coloring principle, is as yet 

 unknown ; it appears to contain no nitrogen, but iron, 

 as an essential ingredient. It dissolves in hydrochloric 

 39 



