IT is well known that numerous tannin matters such as sumach, catechu, divi-divi, &c., dye fabrics mordanted with aluminium pale yellow shades, and this, taken in conjunction with the dark bluishblack that they yield with iron mordant, has frequently been considered a s a property of the tannin substance they contain. As numerous members of the tannin class have been but superficially examined, and many of their principles have probably not yeti been obtained in a pure condition, some of these,

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... i t is possible, may behave as mordant yellow dye-stuffs : on the other hand, however, Lowe has stated that both catechu and sumach contain quercitrin and quercetin (Zeit. anal. Chem., 1874, 12, 127) , and i t is thus evident that, in some cases at least, this dyeing property is due to the presence of a distinct colouring matter rather than to the tannin itself. Wit8h the object of determining how far this is t.he case, and with the desire of ascertaining the class of colouring matters they contain, such as are available are undergoing investigation. Sumach consists of the dried and powdered leaves of the genus Rhus (order Terebinthacae), especially R. corkria and R. cotinus. The former constitutes Sicilian sumach, the best known and most fiequently used variety, the latter Venetian sumach, and it is interesting to notice that it is the wood of this tree (B. cotinzu) whichconstitutes young fustic, the tinctorial properties being due to fisetin. Sumach is useful for tanning the finer kinds of leather, and also in dyeing and VOL. LXIX. s