ON QUINOIDINE. 
37 
cooling, a large quantity of cinchonia separated in crystals, 
and also on further evaporation. At last, a small quantity 
of alkaloid crystallized in the form of fine white prisms. Its 
nature was the same as the alkaloid before mentioned by 
the author under the name of Quinidin. The cinchonia 
thus obtained amounted to three drachms, the quinidin to 
forty grains. Out of the last proportions of the mother 
Uquor there was also obtained by evaporation, a light-brown 
amorphous mass, from which a small quantity of amor- 
phous quinia could be extracted by concentrated sulphuric 
acid. 
Although it cannot be denied that good quinoidine con- 
tains very much alkaloid, there is still even in the best 
qualities, no part of the quinia free. It is always combined 
with a resinous substance. The amorphous quinia is fur- 
ther accompanied by a light-yellow compound, which 
adheres obstinately to it, and renders the purification very 
difficult. The brown compound appears to be some red 
cinchonic, changed by the action of the lime ; the yellow 
compound, however, seems to be a peculiar constituent of 
the bark. Of ten sorts of saleable quinoidine examined by 
the author, only three contained a comparatively large pro- 
portion of amorphous quinia, five contained but little alka- 
loid, and two only traces of it ; and it is in consequence of 
this varying composition of the crude quinoidine, that it 
cannot be recommended for medicinal use. It will, how- 
ever, be advantageous to free crude quinoidine by diluted 
sulphuric acid (one part acid of 1.3S specific weight, and 
two parts water) and by pure ether from the foreign admix- 
ture, so that it might represent a preparation of equal 
chemical composition. If ether containing water and alco- 
hol be employed, a quinoidine of a very different composi- 
tion is obtained, and even if pure ether be used, it will 
depend on the chemical composition of the crude quinoidine 
whether the result will be a pure amorphous quinia, almost 
4 
