Action of Tannin on Organic Salifiable Bases, fyc. 235 
cohol, precipitated by water; bitter, acrid, and afforded an 
abundant precipitate with tannin. 
A watery extract of the fresh leaves of the aconite, treated 
with tannin, gave me, after the evaporation of the alcohol, 
a brown residue, which, redissolved by means of an acid, 
then filtered and decomposed by potash, afforded a very bit- 
ter, acrid, flocculent, whitish precipitate, soluble in alcohol, 
and fusible by a gentle heat into a sort of resin. This pro- 
duct had a great resemblance to what has been described 
under the name of aconitine. 
Caffeine. — M. Boutron has successfully made use of this 
process to extract caffeine. 
Application of Tannin in the detection of very minute quan- 
tities of the Alkaloids. — It often becomes necessary to ascer- 
tain the presence of very small quantities of certain of the 
poisonous vegetable alkalies, which have been added to w r ine, 
soup, coffee, &c, with a criminal intention. By means of 
tannin I have obtained results, which I am of opinion are of 
no little importance in their applications. 
Some years since M. Dublanc, Jr. proposed a similar me- 
thod to detect morphine in cases of poisoning, and M. Orfila 
observes, " this plan consists in evaporating the suspected 
mass to dryness, treating it several times with boiling alcohol; 
adding a tincture of galls to the alcoholic solution, which pre- 
cipitates the animal matter, leaving a compound»of morphine 
and tannin in solution. The fluid is then to be diluted with 
water, and gelatine added, and the alkaloid isolated by means 
of alcohol." M. Orfila, however, adds that after several trials 
he was not satisfied of the advantages of this method. 
Whether the gelatine only effects a partial decomposition 
of the vegetable salt, or from some other cause, this plan has 
never been attended with the desired success.* From the 
good effects I had obtained with tannin, in the extraction of 
the vegetable alkalies, I was of opinion that it would prove 
* Since the above was written, M. Pelouze has stated that the cause of the 
failure of M. Orfila, was probably owing to his having used tincture of galls that 
had been too long prepared, in which gallic acid had replaced the tannin. 
