Application of Tannin as an Alkaloimeter. 43 
ployed can be readily ascertained. I was therefore led to 
return to the ideas above alluded to, and was endeavouring 
to make them practically useful, when the excellent memoir 
on tannin by M. Pelouze made its appearance. In this essay 
it was stated that tannin formed white precipitates with qui- 
nine, cinchonine, morphine, narcotine, strychnine and brucine, 
and which were almost insoluble in water. 
It had been for a long time known that tincture of galls 
formed a flocculent, white precipitate with different organic 
substances, especially with the vegetable alkalies. M. Du- 
blanc had also stated that very small quantities of morphine 
might be detected by this reagent, and my father, in examin- 
ing the action of red wines on cinchona, had shown that qui- 
nine and cinchonine were precipitated by the colouring matter 
of these wines, which acted on them like tannin ; he also 
very judiciously deduced that in the preparation of cinchona 
wine, the white or sweet wines were preferable to those 
which contained much red colouring matter. Berzelius, in 
the fifth volume of his Treatise on Chemistry, also notices 
the action of tannin on the vegetable alkalies, and he thinks 
that certain organic bases might perhaps be isolated, by form- 
ing salts of double decomposition, with their insoluble tan- 
nates, by means of acetate of lead. 
To these facts, I will add, that by means of tannin we can 
detect very minute proportions of the organic alkalies in a 
solution, as the tannates which result are very voluminous, 
of a white colour, and rapidly precipitate themselves. 
Taking these observations as a basis, I have endeavoured 
to use pure tannin as a test of the richness of certain sub- 
stances in alkaloids, and have more especially applied it to 
the different kinds of cinchona. 
I therefore prepared, with care, a certain quantity of pure 
tannin, according to the simple and easy process described 
by M. Pelouze, which I shall briefly notice. It consists in 
taking a glass adapter, the smaller end of which is to be 
partly closed by a dossil of cotton, and the larger provided 
with a good cork ; a certain quantity of powdered galls, suf- 
ficient to fill about one half of the adapter, is to be introduced 
