FROM THE POLYGONUM FAGOPYRUM. 125 
decomposed. When the substance is dissolved in boiling 
water to which a little sulphuric acid has been added, and 
the solution is boiled for some time, no decomposition 
apparently takes place, proving that this colouring matter 
is not, like some others, a copulated compound. Nitric 
acid of ordinary strength dissolves it even in the cold, 
forming a dark orange-coloured liquid, which, on being 
boiled, evolves nitrous acid, and becomes pale yellow; the 
liquid on evaporation yielding a large quantity of oxalic 
acid. When suspended in water, and exposed to the 
action of chlorine gas, it gradually dissolves, forming a 
brownish-yellow solution, which on evaporation leaves a 
brownish-yellow glutinous residue. This residue has an 
astringent taste, which is, however, partly disguised by 
the muriatic acid formed during the decomposition; its 
watery solution gives with gelatine a curdy precipitate, 
similar to that produced with the latter by tannin. The 
colouring matter dissolves easily in caustic potash and 
soda, liquid ammonia, baryta water and lime water, form- 
ing deep yellow solutions, which, on the addition of an 
excess of acid, become pale yellow, and on standing again 
deposit the colouring matter in pale yellow needles. If, 
however, these solutions be left to stand for some time 
exposed to the air, a decomposition of the colouring 
matter seems to take place, for on now adding an excess 
of acid, the solutions remain yellow, and deposit no 
crystals. If the ammoniacal solution be left exposed to 
the atmosphere for some time and then evaporated, it 
leaves a residue consisting of crystals of colouring matter 
mixed with an amorphous substance. On adding water to 
the residue the latter dissolves, and the solution, after being 
filtered from the crystals and evaporated, leaves a trans- 
parent, yellow, brittle mass resembling gum, which 
contains only a trace of ammonia, and is probably a 
