ABSENCE OF GUM AND PRESENCE OF A NEW DIGLUCOSIDE. 27 



and of the "Peppermints," as E. dives etc., as well as in a 

 few others, appear to be identical substances, and have 

 probably the same structural formulae. The "kino red" 

 formed from all these had identical dyeing properties with 

 mordanted cloth, and when fused with potash all gave pro- 

 tocatechuic acid and catechol ; phloroglucinol was not 

 formed by this method. The tinctures of the kinos of all 

 these groups gelatinized with equal rapidity, and all gave 

 very similar reactions with reagents which act on the 

 tannin alone, except with ferric chloride. 



It may thus be supposed that one of the hydrogen atoms 

 in one of the hydroxyl groups belonging to a catechol 

 nucleus, is replaced in the kinos of the " Ironbarks " par- 

 ticularly, by one Eucalyptus sugar residue, thus forming the 

 tannin diglucoside. In the " Stringybarks " and the 

 "Peppermint" kinos this sugar appears to be absent, and 

 my discovery in one of the " Stringybarks " (E, macror- 

 rliynclia) of the glucoside myrticolorin, the sugar of which 

 is glucose, also points to this conclusion. 



The sugar in the tannin diglucoside appears to protect 

 the tannin molecule from that- alteration common with the 

 " Stringybark " and "Peppermint" kinos, because no 

 matter how long the kinos of the " Ironbarks " are kept, 

 they retain their ready solubility in water almost unim- 

 paired, but when the same tannin is free from the sugar, 

 change commences at once after exudation, and although 

 but little coloured when freshly exuded, yet, as the phlo- 

 bophenes form the kinos become darker and less soluble in 

 water and alcohol, and after many years they are almost 

 black and insoluble. By investigating, therefore, a freshly 

 exuded non-glucosidal kino containing this particular tannin, 

 and also free from the other tannins of these kinos, it may 

 be possible to work out the structural formula for the 

 tannin of the whole class of these kinos, glucosidal and 



