212 CHEMICAL INVESTIGATION OF THE RED POPPY. 
calcium, chloride of potassium, sulphate of potash, sulphate of 
lime, phosphate of magnesia, phosphate of lime, carbonate of 
lime and magnesia. Betz and Ludwig mention the occurrence 
of malic and gallic acid, but this the author is inclined to doubt. 
The colouring principle of the flowers consists, according to 
the author, of two acids, one of which he calls rhceadic acid, 
the other papaveric acid. 
To obtain the rhceadic acid pure and unaltered, a solution 
of acetate of lead is poured into a hot concentrated aqueous ex- 
tract of the flowers ; the precipitate which forms is carefully 
washed, alcohol of 0.889 sp. gr. added to it, and as much sul- 
phuric acid as to leave a portion of the precipitate unde- 
composed, and the whole heated to boiling. The filtered solu- 
tion leaves on evaporation a brilliant red amorphous mass, 
which is dissolved in water, and again precipitated with a so- 
lution of acetate of lead. The precipitate is washed with hot 
w r ater, in which the papaverate of lead dissolves, and the resi- 
due is then again decomposed with sulphuric acid. This ope- 
ration is repeated until the liquid above the lead precipitate no 
longer exhibits any colour. This is more quickly effected by 
boiling the aqueous extract of the poppies with carbonate of 
lead, and decomposing the rhceadate of lead with sulphuric 
acid. On attempting to separate the acid from the lead by sul- 
phuretted hydrogen, it is altered. 
Pure rhceadic acid is a shining dark red amorphous mass, 
void of odour, and of a pure acid taste : on exposure to the air, 
it slowly absorbs moisture without deliquescing. It has a 
strong acid reaction, is insoluble in ether, soluble in cold abso- 
lute alcohol and cold water. A grain of the acid imparts a 
red colour to an ounce of water. If the acid is not free from 
papaveric acid, a reddish-brown residue is each time left on 
evaporation and re-solution. The acid yields, with a solution 
of sugar of lead, a bluish-gray precipitate ; the same with 
acetate of copper ; a dark turbidness with perchloride of iron ; 
a dark colour with caustic and carbonated alkalies, and a yel- 
low colour with dilute nitric acid. Nitrate of silver, tincture 
