246 Royal Society. 



colourless. It is very soluble in water, and still more so in weak 

 and strong spirits of wine. By digestion with strong nitric acid, 

 it is rapidly converted into nitropicric acid. In several of its cha- 

 racters nitropopulic acid bears a considerable resemblance to indi- 

 gotic acid. When subjected to analysis, the formula of nitropopulic 

 acid dried in the air, was found to be C,4 H3 No 0|3 + HO + 2Aqu ; 

 that of the acid dried at 212° F., C^ H3 N. 0,3 + HO. 



The potash, silver, soda and baryta salts were also analysed. 



The Popjihis nigra, when treated with nitric acid, was also found 

 to yield nitropopulic acid, which appears therefore to be character- 

 istic of the poplar tribe. 



An extract was also prepared from Salix russelliana, or the Bed- 

 ford-willow, which, when it was digested with dilute nitric acid, 

 yielded a great deal of oxalic and nitropicric, but no nitropo ulic 

 acid. Extracts of the Ci/tisus labitrnum, or the laburnum-tree ; of 

 the Swetenia mahogani, or the mahogany-tree ; of the Pyriis mains, 

 or the apple-tree ,• of the Cratcegus oxyacantlia, or the hawthorn ; 

 of the mhes nigrum, or the black currant bush ; of the Betula alnus, 

 or the alder ; of the Vlex europmus, or the furze ; of the Calluna 

 vulgaris, or common heather ; of the root of the Curcuma longa, or 

 turmeric ; of the seeds of the Bixa orellana, or annotto ; of the 

 Sambucus nigra, or the elder ; of the Cytisus scoparius, the Spar- 

 tium scoparium of Linn., or common broom, when treated with 

 dilute nitric acid, also yielded oxalic and nitropicric acids. The ex- 

 tracts of Qitercus robur, or common oak, and of Betula alba, the 

 birch-tree, when digested with nitric acid, only yielded oxalic acid, 

 but no nitropicric or any analogous nitrogenated acid. 



The results of these experiments seem to indicate therefore that 

 a far greater number of plants are capable of yielding nitropicric 

 acid than has generally been supposed, those which fail to do so 

 constituting a very small minority. 



As the extract of broom, Spartium scoparium, besides yielding 

 nitropicric acid, exhibited some interesting peculiarities, it Avas sub- 

 jected to a more minute examination. When an aqueous decoc- 

 tion of broom was concentrated to about a tenth of its bulk, and 

 set aside in a cool situation for twelve hours, it gelatinized into a 

 greenish-brown coherent mass, which was thrown upon a filter 

 and washed with a little cold water. It consisted chiefly of 

 a yellow crystallizable colouring matter (scoparine, the diuretic 

 principle of broom), which was at first contaminated with a con- 

 siderable amount of chlorophyl. It also contained a small quan- 

 tity of a volatile organic base (sparteine, the narcotic principle of 

 broom), the greater portion of which however remained in the 

 mother-liquors. 



The scoparine, when purified by repeated crystallizations out of 

 hot water and spirits of wine, formed pale yellow prisms of a feeble 

 acid character. Its formula was found to be C^j Hj, O^q. Sco- 

 parine acts as a powerful diuretic. 



The mother-liquor from the crude scoparine, after having been 



