20 
EXAMINATION OF JALAP RESIN. 
times with washed animal charcoal until it acquired a 
bright, faint, wine-yellow color ; the filtered alcoholic so- 
lution was then diluted with water and the alcohol distilled 
off. The resin obtained had a slight yellowish tint, and 
was of the consistence of Venetian turpentine, was boiled 
with distilled water, and treated several times with water, 
which takes up a considerable quantity of resin. Thus 
purified and evaporated to dryness in a water-bath, the 
resin formed a yellowish- white brittle mass, which possess- 
ed the well-known smell of jalap. The dry resin was 
boiled in a retort with aether as long as anything was re- 
moved. Finally, the resin was re-dissolved in a little alco- 
hol, and then precipitated with aether. In this manner a 
colorless, perfectly transparent resin was obtained, a thin 
dry layer of which on a glass plate could scarcely be dis- 
tinguished by the eye. The resin was then evaporated in 
a water-bath to dryness. 
When pulverized it forms a nearly white powder, with- 
out smell or taste, insoluble in water and ssther, but very 
readily soluble in alcohol. It is thrown down of a white 
colour from this alcoholic solution by water ; the precipitate 
dissolves entirely in ammonia and acetic acid. The alco- 
holic solution has a faint acid reaction, dissolves but spa- 
ringly in cold potash, soda and the carbonate alkalies, but 
entirely on the application of heat. From these solutions 
acids do not precipitate it any longer ; it dissolves entirely 
in cold concentrated ammonia with a light brownish color ; 
on expelling the excess of ammonia by heat a neutral so- 
lution is obtained, which may be mixed in all proportions 
with alcohol and water. The solution of this neutral salt 
of ammonia is not precipitated by nitrate of silver, neutral 
acetate of lead, chloride of barium or sulphate of copper ; 
a flocculent precipitate is obtained only by means of basic 
acetate of lead. The solutions of the potash and soda 
salt behave towards these reagents just as the ammonia 
salt. Since the above method would not suffice to obtain 
