PHARMACEUTICAL EXTRACTS. 
179 
One kilogramme (2.205 pounds) of digitalis, in powder, 
afforded me 108 grammes (1666.872 grains) of dry extract; 
but taking into consideration the inevitable losses in operat- 
ing on larger quantities, it may be considered that one part 
of extract is equivalent to ten parts of the dry plant. 
This extract should never be substituted for the ordinary 
extracts unless specially ordered. 
Extract of Valerian. 
According to Trommsdorff 's analysis, valerian root con- 
tains, 
Volatile oil, ^ 
Resin, > soluble in alcohol. 
Peculiar volatile acid, (valerianic acid,) ) 
Aqueous extractive, ~) 
Peculiar substance, > soluble in water. 
Starch, ) 
Experience has shown that the volatile oil, valerianic 
acid, and resin are essentially the active principles of vale- 
rian ; on the other hand, the aqueous extract is not with- 
out action. It is desirable, therefore, to introduce into the 
product as large a proportion as possible of the three first 
substances, the solvent of which is concentrated alcohol, 
and also to admit a certain proportion of the constituents 
soluble in water. 
The following is the mode of operating which I recom- 
mend : — 
Valerian in coarse powder, Q. P. Carefully moisten 
this with twice its weight of spirit, sp. gr. 0.834. After 
bei»g in contact for three days, introduce the mixture into 
an ordinary displacement apparatus, and displace the liquor 
by an equal weight of spirit, sp. gr. 0.915. The first pro- 
duct being distilled over the water-bath, the residue will be 
almost entirely composed of a dark green resin, holding in 
solution the whole of the volatile oil and valerianic acid. 
This product should be set aside in a well-stoppered bottle. 
