232 Keegan : The Chemistry of Some Com.mon Plants. 



cephalas of the great order Compositae, which is specially 

 eminent for a peculiarly repulsive bitterness of taste. The con- 

 stituent to which this is due is called cnicin, and is of silky 

 needles very soluble in, alcohol, and may be regarded as a 

 compound of resin with some impure or decomposed carbo- 

 hydrate residue ; it dissolves red in sulphuric acid, green in 

 HCl. The leaves contain much carotin, also wax, resin, and 

 fat-oil. It is rather peculiar that even as late as mid-October 

 they contain a large quantity of rutin which precipitates bromine 

 water, but not quinine, whereas the fully evolved tannin reacts 

 precisely the reverse. There is no levulose, and very little 

 detectable proteid or starch, but there is much oxalate of calcium 

 in fine crystals, also 10 per cent, of ash in dry containing 37 per 

 cent, soluble salts, 29*4 lime, y6 P'-O®, 4*9 SO^, and 5*8 CL. 

 The flowers contain also much bitter principle, and their pig- 

 ment although pure and beautiful is not well developed ; the 

 ash is rather small in quantity and contains 37*7 per cent, 

 soluble salts, 15 lime, 1 1 "4 P"0', and 4'5 SO^. It is clear, 

 judging- from the above analysis, that the division of Compositae 

 which this plant represents is even more backward, so to speak, 

 in chemical development than the Corymbiferae. 



Cranesbili. Geranium pratense. This plant, on the 

 contrary, is extremely powerfully developed in a chemical sense. 

 It is very local in distribution, doubtless for this very reason, its 

 marvellous root appanage being very fastidious as respects 

 quarters wherein to find a fully suitable lodgement. The 

 chemistry of the rhizome vies with that of any of our native 

 products of a similar character. Starch and mucilage are 

 prominent constituents, and there is over 10 per cent, of tannin 

 which is iron-blueing, and yields under the action of dilute acids 

 a brilliant vermilion-red phlobaphene. It is a very distinctive 

 catechol tannin with powerful chromogenic groups oxidised by 

 alkalies to protocatechuic acid almost entirely (distinguished 

 from Rosaceae). The leaves exhibit a pretty commanding 

 faculty for starch formation. They also contain tannin, con- 

 siderable sug^ar, some malic and oxalic acid, but no free phloro- 

 g^lucin, and (blades only) 7*5 per cent, of ash in dry having 38*8 

 per cent, soluble salts, 25 lime, 9*5 P'^0\ etc. The pigment of 

 the blossoms is highly developed and approaches a true blue as 

 closely as any flax or balsam flower can possibly do. None of 

 these, however, it may be averred, are genuine blues, they being 

 invariably and, as it were, inevitably dashed with red, the 

 approach to the coerulean tint being probably dependent on the 

 comparative ' purity ' of the chromogen, or perhaps it does not 

 possess sufficient 'acidic functions.' 



Naturalist,. 



