36 
AN ESSAY ON LACTUCARIUM. 
the evaporating vessel, is white, friable, easily reduced to 
powder and sensibly bitter. Exposed to the action of 125 
grammes of boiling distilled water, it makes the liquid deci- 
dedly bitter, without sensibly clouding it. The treatment 
causes it to lose a fifth part of its weight. A strong heat 
makes it swell, then liquifies it, and causes it to burn with 
a flame, without leaving the least residue. Thus liquified 
it is extremely adhesive, and very elastic ; ether, alone can 
remove it from the substance to which it adheres; properly 
speaking it is caoutchouc, for it has all the properties of that 
body, and all its physical characteristics. 
It is worthy of remark, that after having been subjected 
to the successive action of alcohol and sulphuric ether, this 
substance still gives up a fifth part of its weight to distilled 
water, and that it imparts a characteristic bitterness to this 
last solvent, without, however, causing it to lose its trans- 
parency. I draw attention to this observation, because it 
will assist me in my judgment when I shall have to give 
my opinion on the nature of the menstruum that should be 
employed to remove the whole of the active matter from 
the lactucarium. 
Treatment with cold distilled Water. 
The nature of lactucarium scarcely allows us to consider 
cold water as a proper solvent of this concrete juice. Still 
the result of several trials made with the greatest care, is 
that it can give up one quarter of its weight of one soluble 
substance or another, if we have recourse to one or several 
macerations of from twelve to twenty-four hours duration, 
with 32 parts or more of distilled water. 
The liquid is in that case extremely bitter, and rather 
milky. Its slow evaporation, in a glass capsule, furnishes 
an extract, which does not appear to differ from the alcoholic 
extract. 
Treatment ivith boiling distilled Water. 
Of all the solvents employed in my different essays this is, 
