94 VEGETABLE SUBSTANCES. 



soluble in cold alcohol, and in the substances 

 already mentioned as solvents of fatty oils ; but 

 they are insoluble in water. 



RESIN. 



The best marked reaction is the red color im- 

 parted by Miiller's tincture of alcannin (p.-4i). 

 Hanstein's aniline violet colors it blue (p. 60). 

 The different varieties of resin are soluble in 

 alcohol and ether, but insoluble in water. The 

 Unverdorben-Franchimont reagent, an aqueous 

 solution of acetate of copper (p. 42), colors the 

 resin a beautiful emerald green in masses of tissue 

 which are allowed to lie in the fluid for several 

 days. 



WAX 



Forms solid crusts, or characteristically -shaped 

 secretions, on the surface of cells. It is insoluble 

 in water, whether cold or hot, but melts in the 

 latter case. It is insoluble, or hardly soluble, in 

 boiling alcohol, but soluble in ether, benzole, chlo- 

 roform and carbon bisulphide. 



SILICIC ACID (Silica). 



Silica frequently incrusts the cell-wall (grasses) 

 or the pedicel of cystoliths, and it is sometimes 

 found in the interior of cells in amorphous masses 



