ON THE GALENICAL PROCESSES AND PREPARATIONS. 
473 
preparation of these extracts necessarily differ in some of their details, be¬ 
cause the sources from which they are derived, or the substances immediately 
yielding them, are very different. in their characters and properties, some 
being vegetable juices,, while others are aqueous, or alcoholic, or ethereal solu¬ 
tions, obtained by processes of extraction from the drugs operated upon ; and 
these are submitted to evaporation to bring the products to the required con¬ 
sistence. 
There are many points to be considered with reference to the preparation 
of extracts,—points relating to the method of extraction and to the process 
of evaporation. Efficient means are required for separating the parts of vege¬ 
table substances which should enter into the composition of the extract from 
other parts which it is desirable to reject. Some substances have to be rejected, 
because, being inert, they would lower the strength of the product too much. 
Others are objectionable because they promote decomposition of more active 
ingredients, either by setting up or supporting fermentation, or by inducing 
the growth of microscopic vegetation. On the other hand, it is sometimes de¬ 
sirable to retain substances which are themselves devoid of medicinal activity 
on account of their giving the required consistence, or some other requisite 
quality or character to the extract. We shall find in these various require¬ 
ments an explanation of the objects contemplated in the modifications which 
have been made in several of the processes for the preparation of extracts in 
the British Pharmacopoeia. Thus, the starch, which by previous processes 
was retained, is now excluded from the extracts of colchicum. In the acetic 
extract of colchicum the quantity of acetic acid is diminished. Albumen is 
also rejected from both extracts of colchicum, as well as from extract of gentian 
and others of the extracts. Extract of jalap is, as formerly, partly an alco¬ 
holic and partly an aqueous extract, but the aqueous extraction is now effected 
with cold water instead of hot water. Extract of hop is also an alcoholic and 
aqueous extract, but the aqueous extraction is here effected by boiling. Ex¬ 
tract of stramonium, which was formerly an aqueous extract, is now made 
with proof-spirit. These I believe are all improvements, and so most decidedly 
is the alteration made in the extract of taraxacum. This has hitherto been a 
soft, treacly extract, containing products of decomposition, formed during the 
process; it is now a good and efficient extract, made by inspissating the ex¬ 
pressed juice of the roots after separating the albumen. Lastly, we have an 
alteration in the extracts made from the expressed juices of green herbs. In¬ 
stead of simply evaporating these juices, as heretofore, in the state in which 
they are obtained by expression, they are now submitted to two preliminary 
operations. The juice is in the first place heated to 130° Fahr., at which tem¬ 
perature the green colouring-matter (chlorophyll) coagulates, and this is 
separated by straining the liquor through a calico filter, and kept for subse¬ 
quent use. The liquor is then again heated to 200° Fahr., to coagulate the 
albumen, which is separated by straining, and rejected. After these two 
separations, the liquor is evaporated by a water-bath to the consistence of a 
syrup, and the green colouring-matter being now mixed with it, the whole is 
evaporated to a proper consistence at a temperature not exceeding 140°. This 
process, which is applied to aconite, belladonna, hemlock, and henbane, certainly 
yields very good extracts, which are smooth, of a good consistence, and keep 
well without becoming mouldy. There is nothing to be said against the pro¬ 
cess with regard to the qualities of the products, assuming that these extracts 
are intended to retain all the colouring matter of the expressed juices. The 
process is similar to that which has long been adopted by manufacturers on 
the large scale, and which has been found to afford satisfactory results. Still, 
it is not exactly the manufacturers’ process, but a refinement upon it, and it 
is doubtful whether this refinement is fully applicable to such operations as 
