PHARMACEUTICAL EXTRACTS. 
ter combined with the gentisine. It is filtered, and evapo- 
ration completed in the stove, and when the product has 
assumed the consistence of thick syrup, it is spread, by 
means of a brush, in thin layers over plates of tin, rubbed 
over first with quicksilver, and then with a cloth slightly 
moistened with oil of almonds. When the extract is dry, 
it is merely necessary to knock the back of the tin plate to 
detach it in beautiful yellow transparent laminae, which 
should be preserved in well-stoppered bottles. 
This extract, it will be observed, contains only the aro- 
matic bitter matter of the gentian, the sugar, the free acid, 
and probably also a certain quantity of gentisine retained 
by the bitter principle. It represents the active principles 
of the gentian in a state of great concentration, and may 
form the basis of excellent preparations. One part of the 
extract is exactly equivalent to two parts of gentian root. 
Extract of Digitalis. 
As with gentian, three successive digestions with spirit, 
sp. gr. 0.834, entirely exhaust the digitalis of its bitter and 
odorous constituents. The liquors are mixed together ; 
two or three litres of distilled water is added, or more, ac- 
cording to the quantity of matter under operation. The 
object of adding this water is to divide the chlorophyl, 
which otherwise carries down with it a considerable quan- 
tity of the active principles. It is then distilled over the 
water-bath to recover all the spirits, allowed to cool, and 
filtered to remove the chlorophyl. Proceeding afterwards 
in the same way as with the gentian, a dry extract is ob- 
tained in the form of fine transparent laminas with very 
little color, but possessed in a high degree of the bitter taste 
and peculiar smell of digitalis. The ^smell becomes very 
perceptible on rubbing the extract, or moistening it with a 
little water. There can be no doubt that this extract is 
very energetic and preferable to all others ; and that in the 
hands of an able practitioner it would form the basis of 
preparations possessing uniform medicinal activity. 
