i 
22 Original Communications. 
On adding to the solution a metallic salt, and then a solu- 
tion of a fixed alkali, the oxide of the metal was thrown down 
with the green matter, in the form of a lake. 
6. The solution obtained in last experiment, with boiling 
water, on being evaporated, yielded a yellow colouring matter. 
7. A portion of the leaves were introduced into a retort, 
heated by means of an oil bath, and water added to them ; 
this was distilled until it came away inodorous ; the exhaust- 
ed leaves were replaced by others ; and the liquid redistilled 
from them ; this operation was repeated till numerous fine 
particles of oil came over with the water. 
8. Digested the residue of the leaves obtained in experi- 
ment 5th, in sulphuric ether ; evaporated the etherial solu- 
tion, and obtained a yellow substance, which left a greasy 
stain on paper, and was insoluble in alcohol. 
9. A tincture made with diluted alcohol, became turbid on 
the addition of water ; the precipitate was separated by fil- 
tration ; the filter was digested in alcohol, which dissolved 
the precipitate ; on the addition of water, the resin was again 
thrown down. 
10. Having digested the leaves severally, in a solution of 
caustic potassa and dilute muriatic acid, a substance was ob- 
tained possessing the properties of lignin. 
11. Incinerated the leaves, and treated the residue with 
water * a solution was obtained which effervesced with acids; 
on concentrating it, it gave a white precipitate with a solu- 
tion of tartaric acid, which was dissolved by heating the wa- 
ter to ebullition, and again precipitated on cooling. 
A portion of the liquid yielded a precipitate with a solution 
of chloride of platinum. 
12. The insoluble residue of last experiment was treated 
with diluted muriatic acid, which occasioned considerable 
effervescence. The solution obtained gave a precipitate with 
oxalate of ammonia and sulphuric acid ; the last did not oc- 
cur till several hours afterwards. 
From the foregoing experiments we may infer that Ameri- 
can senna contains, 1, Active principle of the plant; 2, Al- 
bumen ; 3, Mucilage ; 4, Starch ; 5, Chlorophylle ; 6, Yellow 
