188 
ORIGINAL COMMUNICATIONS. 
carried on, and hence all the responsibility must devolve on 
myself alone. 
"As you have, however, offered me this excuse, and I have 
thus declined it, I trust that you will credit me in stating that I 
never have knowingly augmented any product by foreign ad- 
mixtures, but that on the contrary, my constant aim has been 
to render every article as pure as possible, with a due regard 
to economy in the process. Besides which, the very presence 
of the workmen in my establishment would in itself be a 
guarantee of my good faith; it would be scarcely possible to 
place them all in my confidence and pledge them to secrecy. 
" I therefore pass over this point, and will now detail to 
you the mode in which I operate, that you may perceive the 
cause of the combination of foreign substances you have point- 
ed out in a lot of my sulphate of quinine. 
" The contused bark is subjected to several decoctions in 
water sharpened with hydrochloric acid; these decoctions are 
precipitated with milk of lime. The precipitates are drain- 
ed, washed, subjected to pressure and placed in contact with 
alcohol at 36°. The alcohol containing all the quinine con- 
tained in the precipitates is then distilled, affording a residue 
of crude quinine. 
66 This crude quinine is combined with sulphuric acid and 
animal black to decolourize it. The crystals that result from 
this operation are washed, drained, and again treated with 
sulphuric acid and animal black, affording white crystals fit 
for sale. 
" The coloured mother waters, and the washings are preci- 
pitated by liquid ammonia, and this precipitate treated as 
above; the washings from this operation are then treated with 
alcohol as in the first instance. The mother waters of the 
white crystals are also precipitated by means of ammonia, 
and the precipitates treated with sulphuric acid and animal 
black, affording less perfect crystals than the preceding, but 
equally white and pure. The washings are treated with al- 
cohol, &c. 
It may be seen that in these various decolourations and crys- 
