GENTIANINE. 149 
Upon evaporating this liquor to dryness, washing the residue in water, 
adding a little well-washed calcined magnesia, boiling and evaporating in a 
water-bath, the greater part of the odorous matter of the gentian is driven 
off ; the bitter acid is also taken up by the magnesia, and the yellow bitter 
principle remains partly free, and partly combined with the magnesia, to 
which it gives a fine yellow colour. The greater part of the bitter principle 
may then be obtained pure and isolated, by boiling the magnesia in ether, 
_and evaporating the solution. If it be wished to separate the greater part 
of the bitter principle which remains in the magnesia in a fixed state, and 
which could not be taken up by the ether, we may treat it with oxalic acid, 
in a quantity sufficient to produce slight acidity. The acid unites with the 
magnesia; and the bitter principle, which is left free, may be obtained by the 
means pointed out above. 5 
Properties of Gentianine. This substance is yellow, inodorous, possessing 
very strongly the aromatic bitter taste of the gentian, which is much increased 
by solution in an acid. It is very soluble in ether and in alcohol, and may 
be separated from them by spont 1s evaporation, in the form of very small, 
yellow, needle-like crystals. It is much less soluble in cold water, which, 
nevertheless, it renders extremely bitter; in boiling water it is more readily 
dissolved. Diluted alkalies deepen its colour very much, and dissolve rather 
more of it than water will alone. 
Acids weaken its yellow colour very sensibly ; its solutions in the phos- 
phorie and sulphuric acids, are even almost colourless. Those with the 
weaker acids, as the acetic, are yellowish. Concentrated sulphuric acid car- 
bonizes it, and destroys its bitterness. Exposed in a glass tube to the heat of 
boiling mercury, Gentianine sublimes in the form of small, yellow, crystalline 
needles, and is partially decomposed. It has no sensible effect on turnsol, 
either when blue, or reddened by acids. It appears to be neutral. 
Action of Gentianine on the Animal System. M. Magendie has ascertained 
by experiments that this substance has no poisonous quality: Several grains 
injected into the veins produced no sensible effect. M.Magendie himself 
swallowed twograins dissolved in alcohol, and was merely sensible of the ex- 
treme bitter taste, and a slight sensation of heat in the stomach. 
Medical Employment. M. Magendie prefers the tincture for general pur- 
poses, prepared according to the following formula :— : 
