_Obs._ Of all the inspissated juices (not even excepting that of aconite),
this is the one most readily injured by exposure to the air and heat, and
which soonest loses its qualities by age. Its active principle is CONINE.
Extract of hemlock has a greenish colour, and a strong odour of the
fresh-bruised plant. It is "of good quality only when a very strong odour
of conia (a 'mouse-odour') is disengaged by degrees, on its being
carefully triturated with liquor of potassa." (Ph. E.) "The extracts of
hemlock may become feeble, if not inert, in one of two ways,--either by
the heat being continued after the concentration has been carried to a
certain extent, or by long keeping. On the one hand, I have always
observed that from the point at which the extract attains the consistence
of thin syrup, ammonia begins to be given off in abundance, together with
a modified odour of conine; and, on the other hand, I have found extracts
which were unquestionably well prepared at first, entirely destitute of
conine in a few years." (Christison.) "The most active extract is that
which is procured by moderate pressure from the leaves only." (Brande.)
"The extract of the Ph. D., being freed from the inert albumen and
chlorophyll, contains most of the active principle, and is nearly soluble
in water." (Royle.) On the large scale, the whole of the green portion of
the plant is pressed for juice. 1 cwt. of hemlock yields from 3 to 5 lbs.
of extract.--_Dose_, 2 gr., gradually increased to 5 gr., or more, until
some obvious effect is produced; as an anodyne, alterative, and resolvent
in various obstinate disorders, as glandular and visceral enlargements,
foul and painful ulcers, scrofula, cancer, neuralgia, rheumatism,
troublesome coughs, &c.
5. (Alcoholic; EXTRACTUM CONII ALCOHOLICUM, L.)--_a._ (Ph. Baden.) As
ALCOHOLIC EXTRACT OF ACONITE--Ph. Baden.
_b._ (P. Cod.) As the last, but using proof spirit.--_Dose_, 1/2 to 2 gr.
6. (Dried; EXTRACTUM CONII SICCUM, L.)--_a._ As the DRIED EXTRACT OF
ACONITE--P. Cod.
_b._ (Archer.) By drying the extract of the Dublin College with a
continuous current of warm air.
7. (EXTRACTUM CONII SEMINIS ALCOHOLICUM.) (P. Cod.) _Prep._ Hemlock seeds
in coarse powder, 1 lb; percolate with proof spirit until exhausted.
Distil off most of the spirit, and evaporate residue in a water bath to
pilular consistence.
=Extract of Hemp.= _Syn._ EXTRACT OF AMERICAN HEMP; EXTRACTUM APOCYNI, E.
A. CANNABINI, L. _Prep._ From the root of the _Apocynum cannabinum_, as
EXTRACT OF GENTIAN. A hydragogue cathartic.--_Dose_, 2 to 6 gr.; in
dropsy, &c. The plant from which this extract is prepared is called
'Indian HEMP' in the United States of America, a practice which should be
avoided, as this name is now almost exclusively appropriated to _Cannabis
Indica_, a variety of the common hemp (_Cannabis sativa_, var. _Indica_)
growing in India. See EXTRACT OF INDIAN HEMP.
=Extract of Hen'bane.= _Syn._ EXTRACT OF HYOSCYAMUS; EXTRACTUM HYOSCYAMI
(B. P.), SUCCUS SPISSATUS HYOSCYAMI, L. _Prep._ 1. (Ph. L.) From the fresh
leaves and leafstems of common henbane (_Hyoscyamus niger_), as EXTRACT OF
ACONITE--Ph. L.