TANNIC ACIDS. 427 



tassa, phloroglucin and protocatechuic acid. Treated 

 with zinc and sulphuric acid, it is resolved into phloro- 

 glucin and a white, crystalline substance, machromin, 

 C 14 H 10 5 , which is converted into an indigo-hlue body 

 by the action of light, heat, or oxidizing agents. 



Morin (Moric acid), C 12 H 8 5 . Is contained in old 

 fustic, together with morintannic acid, and, being 

 much less soluble in water than the latter, it can be 

 easily separated from it. Crystallizes from alcohol in 

 almost colorless, shiny needles; almost insoluble in 

 cold water, but sparingly soluble in boiling water. 

 Treated with sodium-amalgam in an alkaline solution, 

 and fused with potassa, it is converted into phloro- 

 glucin. 



ftuino-tannic acid. In the bark of the various 

 species of cinchona, partially combined with bases also 

 contained in the bark. Very similar to gallotannic 

 acid ; precipitates ferrous salts, however, green or gray- 

 ish-green. By boiling with acids it is resolved into 

 sugar and quino-red, C 28 H 22 O 14 , a reddish-brown, amor- 

 phous substance, with weak acid properties, which 

 is itself contained ready formed in cinchona-bark, and 

 can be extracted from it by means of ammonia. With 

 fusing potassa it yields protocatechuic and acetic acids. 



Oak-bark-tannic acid. In oak bark, together with 

 a small quantity of gallotannic acid. The bark ex- 

 tract is subjected to partial precipitation with lead 

 acetate ; the dirty-brown precipitate, which is first 

 formed, and that formed later, of a lighter color, are 

 decomposed with sulphuretted hydrogen. On evapo- 

 rating the filtrate, the tannic acid remains behind as 

 an easily soluble, yellowish-brown, amorphous mass. 

 Its solution is colored a deep blue by iron chloride. 

 By boiling with dilute sulphuric acid, it is resolved 

 into sugar and oak-red, a body very similar to quino- 

 red, which, it appears, is also contained in oak bark. 

 It yields, when fused with potassa, phloroglucin and 

 protocatechuic acid. 



