KEEGAN : THE CHEMISTRY OF SOME COMMON PLANTS. 45 
treated. The berries contain about 6 per cent. fruit-sugar, and 
1°3 per cent. citric and malic acids in nearly equal quantities ; their 
colouring matter is turned blue by oxide of lead, and not green as in 
most other cases, a fact which points to the complete conversion of 
tannin into pigment, 
Primrose (Primu/a veris). ‘Two colouring matters are engaged 
in the decoration of the very conspicuous though not particularly 
vivid corolla of this species. At the base, where the tint is more 
deeply orange, a number of chromoleucites tinctured by carotin are 
assembled, while the rest of the petals are filled by a pale yellow 
soluble pigment. Although the tints are comparatively feeble, 
nevertheless a chemical investigation clearly reveals the fact that the 
plant is capable of exhibiting an infinitely richer wealth of coloration 
than what it actually does show in our climate at all events. I 
seems almost impossible to exhaust the flower heads of substances 
which yield vivid and powerful orange and yellow dyes. The odour 
of the flowers is due to a butyraceous volatile oil; they also contain 
a neutral wax or fat, resin, and a body which gives all the reactions 
of luteolin or quercetin, and is the source of their soluble colouring 
matter. 
ef 
curarine ; it is white, crystalline, froths when its aqueous solution is 
shaken, and dissolves in sulphuric acid with the gradual production 
‘of a reddish-violet coloration ; its chemical relationship has not been 
determined, but it is probably a constructive element aiding nutrition. 
Bogbean (Menyanthes trifoliata). Although this extremely 
beautiful plant grows root and stem right in the pools and shallow 
waters, it must not be considered that its chemical constituents are 
considerably dissolved away by the aqueous element. Far from it ; 
in fact, even the infusion of the plant sweetened with sugar gelavinmes 
in a few days, owing to the presence of a pectin compound or a kind 
of starch called inulin. Stems and leaves have much wax, also a 
tannin which is iron-greening, and when oxidised yields protocatechuic 
acid, but no phloroglucin. The most palpable ingredient of the plant 
is a bitter principle menyanthin C*H®O%, which is only slightly soluble 
in cold water, is yellow and amorphous, and when warmed with a dilute. 
acid yields sugar and a volatile decomposition product of a penetrating 
odour like oil of bitter almonds. There is much resin, and a pentosan, 
oxalate of calcium, and probably also mannite or gentianose. 
ettle ( Urtica urens). It may be wondered how many people 
who have experienced the ‘tropical ferocity’ of this plant inquire or 
care about finding out the particular principle to which they owe 
their tem their temporary irritation. Even the most vandalistic plant-grubber 
February 1897. 
