COMPOSITE. 991 
cium, which is readily soluble in water.. On addition of 
ydrochloric acid, santoninic acid, C'5H*°O*, separates, but 
bs with OH’, Sautonin being thus immediately reproduced. 
170°, which are inodorous, but have a bitter taste, espe- 
cially when dissolved in chloroform or alcohol. They are co- 
s, but not to the other colours of the spectrum, they assume 
yellow hue, and split into irregular fragments. This change, 
hich takes place even under water, alcohol or either, is not 
accompanied by any chemical alteration. This behaviour of 
nin, when exposed to light, resembles that of erythro- 
arin, ©27H%408. ‘he latter has beon obtained by means 
of ether, from the alcoholic extract of Erythrea Centaurium, 
and of some other plants of the Gentianacew. Mehu has shown 
t the colourless crystals of that substance, when exposed to. 
ight, assume a brilliant red colour, without undergoing any 
mical alteration. The colourless solutions of this body in, 
‘tonin, Sestini and Cannizzaro (1876) have shown that.its 
ute alcoholic solution, on long exposure to sun 
bed, resin, sugar, waxy fat, salts of caleium and potassium, 
ad malic acid; when carefully selected and dried, it yielded 
3 6°5 per cent. of ash, rich in silica. (Pharmacographia, 2nd 
Hell, Sturcke and Ritter, and Messrs. Wallach and 
bi The latter puthors confirm the statements of previous 
‘Santonin forms crystals of the orthorhombic system melting 
less, but when exposed to daylight, or to the blue or violet 
roform or alcohol yield the original substance. Yetas to 
affords 
compound ether of photo-santonic acid, es gio ONE O# : 
H " 
