172 
ON THE EXTRACT OF HEMLOCK. 
the preparation of the extract, as these substances are generally be- 
lieved to be inert. 
When the expressed juice was heated to 110° Fahr., and al- 
lowed to cool, the whole of the chlorophylle subsided, while the 
albumen remained in the supernatant liquid in an uncoagulated 
state ; for the purpose of obtaining these two apart from each 
other, the liquid containing the albumen was filtered from the 
chlorophylle, heated to 212° F. in order to separate the latter, and 
again filtered. This second filtrate was evaporated in the hot air 
apparatus before mentioned, the product was an extract of a brown 
color, perfectly soluble in cold water ; from the aqueous solution 
of this extract, alcohol precipitated a large amount of mucilagi- 
nous matter. 
By washing with cold water, the peculiar odor of hemlock-juice 
could be entirely removed from both the chlorophylle and albumen, 
anl as no smell of conia was evident on rubbing either of them 
with solution of potash, it would appear that the general opinion 
regarding the inertness of these two substances is correct. Caustic 
potash appears to be a very delicate test for conia ; if any sub- 
stance containing merely a trace of this alkaloid, be rubbed with 
liqucr potassse P. L., its presence is at once manifested by the de- 
velopment of its peculiar odor. 
Some experiments w T ere made with the view of ascertaining how 
far the officinal tinctures of hemlock might be regarded as uniform 
and efficient preparations. 
Different specimens of hemlock leaves lost by drying from six- 
ty-five to eighty per cent ; it is evident, therefore, that equal 
weights of fresh leaves, obtained under different circumstances, 
will give very unequal results in the strength of preparations made 
according to formulae in which a given weight of fresh leaves is 
ordered. Neither can the expressed juice be used with advantage 
where a given quantity is ordered, as its density varies consider- 
ably, depending in great measure on the state of dryness of the 
plant. 
It would appear then, that by the use of dried leaves this source 
of error may be avoided, and the uniformity of the preparation 
sufficiently secured, especially as these can be obtained in a pretty 
equable state of dryness, and with a very slight deterioration of 
their physical and chemical properties by the use of the hot-air ap- 
paratus before alluded to. 
