24 
Original Communications. 
On macerating the leaves for several days in water, in a 
warm room, they were found to have undergone putrefac- 
tive fermentation, owing to the decomposition of the albumen 
which they contain. 
The manner in which experiment 4th was conducted ap- 
pears necessary, as in several attempts the existence of starch 
was not shown by the addition of tincture of iodine to the de- 
coction, decolourized by animal charcoal ; the quantity ex- 
isting- is very minute. 
The yellow colouring matter may be most readily obtained 
by acting on the extractive matter with sulphuric ether, and 
evaporating the solution ; it has the following properties : it 
is soluble in alcohol, ether, boiling water and the acids ; pre- 
cipitated from its solutions by alkalies of a brick red colour, 
and restored to its solution unchanged by the addition of an 
acid. 
Water distilled from the leaves has a nauseous taste ; the 
volatile oil is colourless, and possesses the peculiar odour of 
the plant, and this odour depends entirely on the volatile oil, 
as it is not possessed by the active principle. 
On treating the powdered leaves with sulphuric ether, and 
evaporating the solution, there was formed a solid substance ; 
also, floating on the surface of this, a peculiar oily substance, 
of an exceedingly acrid taste ; it very soon united with the 
mass. The experiment was repeated several times for the 
purpose of obtaining this supposed fixed oil, but without suc- 
cess. By taking away every thing soluble in alcohol from 
the green mass, there remained the yellow fatty substance 
before noticed ; this, of course, is insoluble in alcohol, and 
appears to be the union of wax with fixed oil. 
The residuary leaves from the preceding process yielded 
nothing to boiling ether. 
Cathartin, the term applied to the active principle of senna, 
is indefinite ; other cathartic principles being equally entitled 
to it. It is most probable this principle exists, more or less 
modified, in all the cathartic species of cassia. On this sup- 
position I would propose the term cassin, (changing the last 
^fitter of the generic name) as a substitute. 
