Mr. Home on the 
5 * 
When tincture of rhubarb is mixed with blood just taken 
from the arm, its colouring matter is afterwards found both in 
the serum and in the coagulum. 
When blood is drawn from the arm of a person, who has 
taken rhubarb in sufficient quantity to affect the urine, the se- 
rum is found to have, a slight tinge from it, equal to that, which 
one drop of tincture of rhubarb gives to half an ounce of serum 
when added to it. 
Half an ounce of tincture of rhubarb, diluted in ounce 
of water, taken in the interval between meals, did not pass off' 
by urine in less than an hour, and even then was not in suffi- 
cient quantity to be discovered, till the test was applied. 
The same quantity was taken immediately before a break- 
fast consisting of tea. In 1 7 minutes, half an ounce of urine 
was voided, which when tested had a light tinge. In 30 
minutes another half ounce was made, in which the tinge 
was stronger ; and in 41 minutes a third half ounce was made, 
in W'hich it w^as very deep. In an hour and ten minutes 7 
ounces were voided, in which the tinge of rhubarb was very 
weak, and in two hours twelve ounces were voided, in which 
it was hardly perceptible. 
In 6 i hours the rhubarb acted on the bowels, and gave a 
decided tinge to the faeces ; the urine made at the same time 
had a much stronger tinge, than what was voided at one hour 
and ten minutes. 
In this experiment, the rhubarb appeared to have escaped 
from the cardiac portion of the stomach ; and in two hours 
ceased to pass through that channel ; but was afterwards- 
carried into the system from the intestines, and again appeared 
in the urine. 
