158 TAXXINS. 



Eaabe found 33 --i per cent, of oxide of lead in the lead-salt, and 

 16-64 of oxide of copper in the copper-salt.^ 



Morintannic acid, which occurs together Avith morin, andmachirin 

 in fustic, also yields phloroglucin and pi^otocatechuic acid by 

 fusion vnth potash. Boiling water extracts morin from the 

 wood in the form of a calcium-compound, which is sparingly 

 soluble in cold water, and is deposited, therefore, from the de- 

 coction on cooling. Alcohol acidified with sulphuric acid decom- 

 poses the compound, dissolving the morin ; the latter crystallizes 

 from alcoholic solution in yellow needles, which are sparingly 

 soluble in cold, but more freely in boiling water. With acetate 

 of lead the boiling alcoholic solution gives an orange-red precipitate 

 containing 58-4 per cent, of oxide of lead. 



According to Loewe, an aqueous solution yields both morm- 

 tannic acid and maclurin to acetic ether. By dissolving the 

 evaporation-residue in cold water and adding chloride of sodium 

 an amorphous precipitate of the former is obtained, whilst the 

 latter crystallizes out on standing. Maclurin is insoluble in a 

 mixture of equal volumes of Avater and saturated solution of salt, 

 whereas morintannic acid is dissolved. Morintannate of lead 

 contains 64 '23 per cent, of oxide of lead. No accurate method 

 of estimation is known. 



The doubt that has recently been thrown upon the giucosidal 

 nature of rhatania-tannic acid renders it very. desirable that kino-, 

 tormentil- and bistort-tannic acids should be examined afresh. - 

 These tannins yield similar products when fused Avith jjotash. 

 Kino-tannic acid is characterized by the disposition its alcoholic 

 solution shows to gelatinize. According to Günther both kino- 

 and tormentil-tannic acids can be estimated by gelatine-solution 

 (see above, and also § 52, xii.), 1 cc. of Avhich indicates O'OISO 

 gram kino, and 0'0168 gram tormentil-tannic acid. 



For ellacjo-tannic acid see below. 



The tannin of the liorse-chestnut,^ Avhicli is likewise non-glucosidal, 



^ Possibly there is another copper-salt containing 22 to 23 per cent. CuO ; 

 that would, at least, appear probable from some experiments of Günther. 



- For the tannin of kino see Eisfeldt, Annal. d. Chem. und Pharm, xcii. 

 101, 1854 ; for its crystalline decomposition-product, kinoin, see Etti, Ber. d. 

 d. chem. Ges, xi. 1879 (Journ. Chem. Soc. xxxvi. \h9). Tormentil-tannic 

 acid is discussed by liembold, Annal. d. Chem. und Pharm, cxlv. 5, 1868 

 (Amer. Journ. Pharm, xl. 311). 



•* Compare Chem. Centralblatt, x. 318 ; xii. 513. 



