77- 



THE CHEMISTRY OF SOME COMMON PLANTS. 



P. Q. KEEGAN^ LL.D., 

 Patterdale, Westmorland. 



Dog's Mercury [Mercuricilis fercnnis). — It is delightful in early 

 spring to see the mother earth of coppice woods and shad}^ 

 hedgerows studded wdth the brilliant greenery of this highly 

 social and uniform plant. Tt affects a lime soil rather, and is 

 more abundant there, but it is very common on clays. It 

 belongs to a large order which is distinguished by the presence 

 of a very poisonous latex indicative of extensive decompo- 

 sition setting in among the products of deassimilation. On 

 May 28th the leaves contained 1.4 per cent, of matters extract- 

 able b}^ boiling benzine including much carotin, with a little 

 wax and resin. The aqueous solution of the alcoholic extract 

 was deep blue and cloudy, and had no tannin ; on adding HCJ 

 it turned red, and a resinous precipitate was deposited which, 

 with sulphuric acid, gave a brown or 3'ellow colour. There 

 was also another resin which dissolved in the same acid with a 

 brown-violet colour. The aqueous extract of the leaves was 

 green, but on evaporation it becomes deep red, and gives a 

 dirty green precipitate with acetate of lead. There was very 

 little sugar, mucilage or starch, but much whitish flocculent 

 matter (pararabin), and small crystals of oxalate of calcium. 

 The ash of the overground parts of the plant amounted to 11.5 

 per cent, in dry, and contained 44.5 per cent, soluble salts, 

 4 silica, 21.4 lime, 4.8 magnesia, ^V^O^ , 6.9 chlorine, and 

 5.6 SO^. The plant contains choline, and hence on distilling 

 wdth water, the fishy-smelling gas trimethylamine passes over 

 with the vapour. The peculiar blue pigment which is developed 

 during drying is called bizetta, and was shown by Lehmann and 

 Molisch to be not related to indigo. It is reddened by acids, but 

 the blue colour is not restored by alkalis, and is colourless in the 

 juice, and only turns blue by the action of a ferment on ex- 

 posure to the air during the general drying up and dying of the 

 protoplasm. The poisonous principle, which is fatal to sheep, 

 is an oil which seems nearly allied to the well-known irritant 

 and acrid croton oil. 



Ribwort [Plantago lanceolaia). — This extremeh^ common^ 

 perennial plant is famihar by reason of the anatomical structure 

 of its flower stock (scape), which is surrounded by a ring of 



1908 March i. 



