PHARMACEUTICAL EXTRACTS. 
175 
posing action which organic bodies so readily undergo in 
contact with chemical agents, such as heat, air, and water. 
Based upon these principles, I will here give an expla- 
nation of the mode of operating which I adopt for the pre- 
paration of some extracts, selected from amongst those most 
frequently employed. 
Belladonna, Stramonium, Hyoscyamus. 
Most of the solanacese, and especially those named above, 
contain active principles, the chemical characters of which, 
and their action on the animal economy, are very similar. 
In preparing the extracts of belladonna, stramonium, 
hyoscyamus, and some other solanaceae, I take 
The leaves and branches at the commencement of in- 
florescence, 
Alcohol, sp. gr. 0.834, of each equal parts. 
The plant is carefully crushed in a marble mortar, ex- 
pressed with the hands, then again submitted to the action 
of the pestle. The juice obtained is added again to the 
plant, the alcohol is also added, and the whole allowed to 
macerate for six days. It is then thrown on to a strainer, 
and the marc submitted to the action of a powerful press. 
The liquors being put together and filtered, are distilled in 
vacuo, if possible, or otherwise over a water-bath, to reco- 
ver the alcohol. In distilling over a water-bath, no altera- 
tion takes place in the product, as it is not exposed to the 
influence of the air. The residue is allowed to cool, and is 
afterwards filtered to separate the clorophyle which is pre- 
cipitated ; it is now evaporated in vacuo, or if the neces- 
sary apparatus is not attainable, the product is put out, to 
the thickness of four-fifths of an inch, in large tin moulds, 
the surfaces of which have been rubbed with quicksilver, 
and left to spontaneous evaporation in a stove having a 
constant current of air heated from 95°to 104°Fahr. When 
the extract has acquired the consistence of honey, it is again 
