Keegan : The Chemistry of Some Common Phints. 231 



shoots up with eminent vig"our and obtrusiveness. The 

 chemistry is very noteworthy, indeed very remarkable in some 

 respects. For instance, it contains free cinnamic acid, a body 

 that is not found, I beUeve, in any other British plant. The 

 leaves contain much carotin, some free palmitic and butyric 

 acids, and a good deal of resin. The tannin is identical with 

 that of coffee beans (caflfeetannin). Choline also occurs and 

 some mucilagfe, but the amount of proteids, starch, sugars, etc., 

 is evidently below the average. The ash of the dried leaves 

 amounts to 8*9 per cent., and is rich in phosphorus and sulphur, 

 moderately rich in lime, but rather below the average in potass. 

 On the whole the plant is decidedly more odoriferous than would 

 be supposed; in the course of the analysis the effluvia emanating 

 from the various cinnamene derivates, the choline, and the 

 butyric acid suggest and recall that even in darkest Britain 

 there is a pseudo-imitation and aping after the ' perfumes of 

 Arabia.' At all events, although the 'tropical' suggestiveness 

 is not so strong as in the Dock tribe, the hydrocarbon derivatives 

 being on a lower footing, we have here a plant whose chemical 

 features are worthy of careful and profound study and contem- 

 plation. 



Hawk-bit. Hieracium hirtus and autumnalis. The 

 ' splitting ' systematist revels in the Hawkweeds, but after all 

 their physiology as revealed by chemistry does not seem to be 

 quite so contentious or diverse. In fact, the entirety of one of 

 the largest, best characterised, and most natural orders in the 

 vegetable kingdom, i.e., the Compositae, is distinguished by a 

 special peculiarity in the process of deassimilation, whereby 

 while an abundance of tannin is produced it is nevertheless in- 

 complete, and hence there is likewise a very appreciable evidence 

 of volatile oils, resins, bitter principles, etc. The plants under 

 review do not present any very special feature. There is very 

 little carotin in the leaves, but resin is present in considerable 

 quantity. The alcoholic extract is bitter and contains rutin 

 which precipitates bromine water, and a tannin which does not. 

 The latter is allied to caffeetannin and is a derivative of styrol. 

 Some mucilage, a small quantity of inulin, but very little protein 

 or starch are observable. The ash is very high, viz., 12-6 per 

 cent., and is rich in lime, but rather poor in potass and phos- 

 phorus. The flower heads are tinctured by carotin, and contain 

 much rutin, some inulin, and (air-dried) 7 per cent, of ash 

 having 44-3 per cent, soluble salts, 16-4 lime, 9*28 P-O', and 

 5-8 SO''. 



Knapweed. Centaurea nigra. This is also a very common 

 composit e plant belonging to the division or sub-order Cynaro- 



1903 July I. 



