TANNIC ACIDS. 427 



tassa, phloroe;lucm and protocatechuic acid. Treated 

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

 glucin and a white, crystalline substance, machromin, 

 G&quot;H 10 5 , which is converted into an indigo-blue 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 m 

 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 gallotanmc 

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

 ish-o-reen. By boiling with acids it is resolved into 

 sugar and quino-red, C 28 H 22 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. 



