62 ORD. XXXII. Gruinales. QUASSIA EXCELSA. 
druggists. Quassia-wood is inodorous, its taste intensely bitter: both water 
and alcohol take up its bitterness. The watery infusion, evaporated by a 
low heat to dryness, leaves a brownish yellow, somewhat transparent, . 
intensely bitter substance, which continues ductile for some time, but by 
degrees becomes brittle. This substance has been regarded as a vege- 
table constituent sui generis, by its discoverer, Professor Thomson, of 
Glasgow, who has named it Quassine.* Quassine possesses the following 
properties :—When heated it softens, swells, and blackens ; then burns away 
with but little flame, and leaves a small quantity of ashes: it is very soluble 
in alcohol and water: it does not change the colour of the infusion of litmus. 
The alkalies produce no alteration in the diluted solution of the bitter 
principle. Lime-water, barytes-water, and strontian-water, occasion no 
precipitate ; neither is any precipitate thrown down by silicated potass, alu- 
minated potass, or sulphate of magnesia. Oxalate of ammonia occasions 
no precipitate, neither does “corrosive sublimate, nor nitrate of mercury : 
nitrate of copper and the ammoniacal solution of copper leave it unaltered; 
but muriate of copper gives a white precipitate, which falls when this liquid 
salt is dropped into water. Nitrate of silver renders the solution muddy, 
and avery soft, flaky, yellow precipitate falls slowly to the bottom. Sul- 
phate and permuriate of iron occasion no change. Muriate of tin turns the 
solution muddy, but occasions no precipitate unless the solution is concen- 
trated ; in that case a copious precipitate falls. Acetate of lead occasions a 
very copious white precipitate, but the nitrate of lead effects no alteration. 
Nitrate of bismuth produces no change ; though, when the salt is dropped 
into pure water, a copious white precipitate appears. Tartar emetic leaves 
it unaltered; but when the muriate of antimony is used, the white precipi- 
tate appears, which always falls when this salt is dropped into pure water. 
Muriate and arseniate of cobalt, arseniate of potass, tincture of nut-galls, and 
gallic acid, produce no effect. The little action of the different re-agents is 
remarkable ; nitrate of silver and acetate of lead being the only substances 
which throw it down.t These properties Dr. Thomson remarks, are suffi- 
cient to convince us that the bitter principle differs considerably from all 
other vegetable principles. 
* Vide Thomson’s Chemistry, 4th edit. v. 32. 
+ Hence nitrate of silver and acetate of lead are incompatible in formulz with it. 
