246 ur. e. schunck on the 



It dissolves in an alkaline solution of protoxide of tin, and the 

 solution on exposure to the air becomes covered with a blue 

 film. It is soluble in concentrated sulphuric acid forming a 

 blue solution, which remains blue even after dilution with 

 water. It imparts to boiling alcohol a bright blue colour, and 

 the solution on cooling and standing deposits blue flocks. 

 When heated in a tube it gives a purple vapour which forms 

 on the colder parts of the tube a blue sublimate. 



Provided with this test I proceeded to examine the urine of 

 a number of individuals, and I succeeded in obtaining indigo- 

 "blue in so great a number of instances, that I have no hesita- 

 tion in saying that the indigo-producing body, if not exactly 

 one of the normal constituents of urine, occurs more frequently 

 than any other of the abnormal ones. The urines containing 

 it exhibit no remarkable or peculiar appearance whatever; 

 they are acid, clear, and of the usual colour. Its occurrence, 

 at least if its quantity is moderate, is not to be considered as a 

 pathological phenomenon. 1 can at all events state from my 

 own experience, that its presence is not attended by any 

 symptoms of ill health or feelings of discomfort, and that 

 neither from the state of the health nor the appearance of the 

 urine can any conclusions be drawn as to its presence or 

 absence. The small number of samples of morbid urine, 

 which I had an opportunity of examining, yielded, with one 

 exception, no more indigo-blue than the generality of healthy 

 urines. Nevertheless, there are no doubt diseases in which 

 the quantity of the indigo-producing body may become so 

 large as to constitute a truly morbid symptom, and it may 

 therefore become a matter of importance and interest for the 

 medical man to have a ready means of detecting it. The 

 delicacy of the test which I have described, as well as the 

 small quantity of the substance usually present, may be 

 judged of from the fact that by working for several weeks on 

 the urine of two individuals, which contained a comparatively 

 large quantity, I obtained one grain of indigo-blue. Even 



