STRUCTURE AXD USES OF THE SPLEEV. 379 



tion of madder being injected, one fourth part of the quan- 

 tity thrown in had escaped. The cells of the spleen were 

 na ore distinctly seen than in the former experiment, parti- 

 cularly at the great end. 



Although there was every reason to believe, that the co- Madder not 

 louring matter of tlic madder had been conveyed into the ^f 1,^'e^peS 

 urinary bladder, yet so muddy and indistinct was the colour, ment. 

 that it was by no means completely ascertained. I there- 

 fore resolved in my future experiments, to make use of 

 some colouring substance, the presence of which could be 

 detected in a very diluted state, by means of a chemical 

 test; and I requested Mr. \V Brande, of whose assistance 

 I have before availed myself, to point out the substances 

 best fitted for this purpose. He immediately suggested, that Rhubarb sug- 

 rhubarb was a substance, which he had made use of as a^^^'^ * 

 test to ascertain the presence of alkali, and therefore had 

 no doubt, that the caustic alkali would prove a test of 

 rhubarb. This substance has also another advantage; it is 

 well known to pass very readily by the kidneys, without 

 being decomposed. 



The following are the results of experiments made witli Trials ©f its 

 rhubarb, to ascertain the best modes of detecting it in the ''')"• 

 urine and blood, and the time it takes to pass from the sto- 

 mach to the urinary bladder. • 



Five drops of tincture of rhubarb, added to 3 ounces of ^n water, 

 water, are found to strike an orange tint when the test is 

 added, which does not take place when the rhubarb is more 

 diluted. 



Six drops of tincture of rhubarb, added to three ounces of In serum, 

 serum, are readily detected by the eye, but the colour is not 

 heightened by applying the test; the alkali contained in the 

 serum being sufficient to strike as bright a tint, as that quan- 

 tity of rhubarb can receive from the addition of alkali. 



When tincture of rhubarb is mixed with blood just taken In blood, 

 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, Avho has Gets into th« 

 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 



