CHEMICAL HISTORY OF GENTIAN ROOT. 
335 
ticable, that I obtained it, after several crystallizations, com- 
pletely deprived of its bitter taste. It is this circumstance 
v^^hich induced me to undertake some experiments upon gen- 
tian, in order to discover the nature of the bitter principle; 
the substance which had been regarded as such, not being the 
yellow crystallizable matter, which does not possess any bit- 
terness. 
In the course of my experiments, I have been enabled to 
observe, that when submitting gentian to the action of solvents, 
it is important to take into account the differences of purity, of 
concentration, and of temperature. I shall endeavour to show 
this, by noticing the principle ones — ether, alcohol, and water. 
Ether, deprived of alcohol, and perfectly dry, brought in 
contact with gentian, pulverized, and deprived also of its hy- 
grometric water, affords a liquid, little coloured, which, by 
evaporation, leaves a product possessed of very little bitter- 
ness. If, on the contrary, ordinary ether is employed, which 
is always mixed with a little water and alcohol, and gentian 
charged with the humidity of the atmosphere, the liquid is 
more coloured, and affords as a residue a very bitter substance. 
By operating with dry ether and dry gentian, I have always 
obtained, as the product of evaporation, a soft substance exces- 
sively sticky, without the appearance of crystals, and composed 
of glue, oil, and gentianin. By employing humid materials, I 
have constantly had mixed with the first product, a brown 
substance, excessively bitter, acid, soluble in alcohol, and par- 
tially in water, appearing to be formed of a sort of extracto- 
resinous matter, an acid strongly reddening litmus, and a 
very bitter deliquescent substance. 
By treating gentian with boiling alcohol at 40°, a liquid 
little coloured is obtained, which, upon evaporation, affords an 
excessively bitter extract, composed of a fixed oil, a yellow 
crystallizable substance, resin, sugar, free acid, and bitter 
extract. If the alcohol is employed cold, the extract is 
less coloured, and affords small yellow crystals, formed in the 
glutinous mass. It also contains less resin. 
Alcohol at 35°, whether hot or cold, furnishes an extract 
