

XIII. — On the Occurrence of Indigo-blue in Urine. 

 By Edward Schunck, Ph.D., F.R.S. 



[Read Aprillth, 1857.] 



The occurrence of urine exhibiting various peculiar and 

 abnormal colours is a phenomenon which has frequently 

 attracted the attention and excited the curiosity of patho- 

 logists. Of these variously tinted urines the most remark- 

 able and striking are the black and the blue, but they are 

 at the same time so rare, that it has been deemed of im- 

 portance to record minutely the symptoms exhibited in each 

 case as well as the chemical and physical properties shown 

 by the urine itself. These urines have been observed in 

 diseases of the most different kinds, as well as in cases in 

 a the general health seemed not to be in the least degree 

 affected. The pigments themselves, to which the colours are 

 due, have not until lately been subjected to any chemical 

 examination, and great doubts still prevail regarding their 

 true nature. The blue pigment, to which I propose to con- 

 fine myself on the present occasion, has been discovered in 

 two states. In some cases it has been found ready formed so 

 as to impart to the urine a blue colour, but merely in a state 

 of suspension and therefore easily separated by simple filtra- 

 tion, whereas in other cases it has only made its appearance 

 when the urine was left to stand or was subjected to the action 



