ON THE CONSTITUENTS OF LACTUCARIUM. 63 
of caustic soda and boiling, the oxide is reduced to pro- 
toxide, and the liquid acquires a dark brown colour; on 
adding now a little muriatic acid, brown humus-like flakes 
subside. There was no sugar contained in the acid, a point 
which was ascertained with certainty. A solution of ace- 
tate of lead gives a white precipitate ; nitrate of silver is not 
precipitated, but on the addition of caustic ammonia and 
boiling, it is reduced to metal. The peracetate of iron 
yields with it after some time a white precipitate ; concen- 
trated sulphuric acid is coloured yellow in the cold; on the 
application of heat it becomes reddish brown and black, 
with evolution of sulphurous acid. Concentrated nitric 
acid is coloured faintly yellow by it. Heated in a platinum 
dish, the acid melts, becomes brown, gives off acid vapours, 
and leaves a voluminous cinder, which is entirely consumed. 
Lactucine which has been decolorized with animal char- 
coal and purified by recrystallization, forms white pearly 
scales, the solution of which exhibits no reactions with basic 
acetate of lead, peracetate of iron and iodine water. Con- 
centrated sulphuric acid affords a colourless solution with 
it in the cold; when heated, the liquid becomes yellow, 
brown, and finally black. Hydrated oxide of copper is re 
duced to protoxide by it and the addition of potash. Lac- 
tucine melts when heated, without being coloured ; at a 
higher temperature it becomes brown, and leaves a porous 
cinder, which is easily burnt. 
The aqueous solution of the alcoholic extract of lactuca- 
rium, after separation of the brown mass containing the 
lactucic acid, left on slow evaporation a yellowish-white 
somewhat crystalline mass, which, extracted with hot alco- 
hol of 0.851, left on evaporation a neutral, insipid, sweetish 
body, crystallizable from water, but incapable of fermenta- 
tion. The spirituous solution yielded on evaporation long 
silky prisms, which had all the characters of mannite. 
The precipitate above obtained by agitation with hydrate 
