ON QUINOIDINE. 
35 
colour, yields upon the addition of carbonate of soda, the 
quinoidine, which is likewise to be washed with hot water, 
and dried in the water bath, together with that obtained 
before. The quinoidine thus obtained forms a yellowish 
white powder, which becomes electrical by friction, and 
dissolves perfectly in acid, spirit of wine, and also in ether, 
in which latter, a brown, resinous, bitter substance is pre- 
cipitated. Four ounces of the best quinoidine furnished 
thirty drachms of purified quinoidine, whilst very inferior 
sorts only contained a very small quantity of the same. If 
quinoidine, as it is obtained in commerce, be dissolved in 
diluted sulphuric acid (1 part to 3 — 5 parts of water) 
purified quinoidine is also obtained by the foregoing method, 
but the separation of the brown, resinous combination takes 
place imperfectly, consequently the product is less pure. 
Still the diluted acid is well adapted for purifying inferior 
sorts of quinoidine from foreign admixtures, which cannot 
be dissolved by acids. 
Experiments were now made to purify quinoidine, by 
ether. Eight ounces of a very excellent sort of quinoidine ob- 
tained from yellow cinchona {cinchonia regi(i) were mixed 
with twenty-four ounces of pure ether. The powder im- 
mediately conglomerated into a resinous mass, whilst the 
ether assumed a yellow colour, like gold. The ethereal 
solution having been poured off after a few days' digestion, 
was treated with animal charcoal and evaporated: four 
ounces of a pale-yellow, resinous, very bitter residue was 
obtained. This was converted by the necessary quantity 
of very diluted pure sulphuric acid into a neutral salt, and 
the solution evaporated by a gentle heat. Very soon a 
rather large quantity of pure sulphate of quinia crystallized 
out of it. This having been removed, no more crystals 
formed, even by further concentration. The solution was, 
therefore, again diluted, treated with purified animal char- 
coal, and the filtrate mixed with the necessary quantity of 
ammonia for precipitating the amorphous quinia contained 
