American Senna. 
23 
colouring matter ; 7, Volatile oil ; 8, Fatty matter ; 9, Re- 
sin ; 10, Lignin ; 11, Potassa ; 12, Lime. 
By comparing these constituents with those found in im- 
ported senna, it will be seen that the composition is very 
similar. Several experiments were made to ascertain the 
presence of other substances, supposed to exist in the plant, 
but without avail. The pods were found to contain the ac- 
tive, and most probably the other principles of the plant ; but 
the quantity of them was too small to operate on to advan- 
tage. 
One thousand parts of the leaves give 396 parts of watery 
and 160 parts of alcoholic extract: inversely, 300 of alco- 
holic, and 256 of watery extract; making 140 parts of ex- 
tractive matter. 
The extractive matter may be obtained by acting on the 
watery extract, (dried,) with pure alcohol; it is of a dark 
reddish brown colour, and possesses the virtues of the 
plant. 
In solution it is affected by the atmospheric air, when ex- 
posed to its influence ; but does not become turbid in a vial 
that is closely stopped. 
The active constituent is of a yellowish red colour, having 
the taste and medicinal -properties of the plant, in a concen- 
trated degree. Its colour is rather lighter than that of ca- 
thartin, and its taste but slightly similar ; its odour is entirely 
different. Forty grains produced similar effects on the sys- 
tem with an equal quantity of cathartin. It is, like that sub- 
stance, deliquescent ; its watery solution is not affected by 
exposure to the air, tartrate of antimony, or acetate of lead ; 
but is precipitated by an infusion of galls, and subacetate of 
lead. It is, in all probability, a modification of the substance, 
the active principle of imported senna, and as such can 
hardly be ranked as a distinct proximate principle. When 
taken into the system, it produces a griping effect, which is 
obviated by combining with it a saline substance ,* this acts 
by qualifying the system, and produces no effect on the prin- 
ciple, as this was obtained pure from a decoction of the 
leaves, formed with the addition of a salt. 
