524 APPENDIX. 



The nitric acid oxydises the uroxanthin, and converts it into 

 uroglaucin and urrhodiu. Sulphuric and hydrochloric acids act 

 similarly, but with less activity. If albumen is present in 

 urine treated in this manner, it is either precipitated blue at 

 once, or assumes that tint gradually, according to the amount 

 of uroxanthin. This is constantly noticed in Bright' s disease 

 on treating urine abounding in uroxanthin with an acid, and 

 allowing it to stand for a couple of days; uroglaucin separates 

 in dark blue crystalline groups, visible to the naked eye, partly 

 on the surface and partly at the bottom of the vessel. On 

 taking a drop from the surface and examining it under the 

 microscope, uroglaucin is seen in the form represented in 

 Plate iii, fig. 37. 



To separate the two products of oxidation of uroxanthin, we 

 collect on a filter the sediment thrown down by nitric acid, and 

 agitate it with cold spirit of '830, which takes up the urrhodin, 

 (as also does ether ;) the residue is boiled for some time with 

 spirit of the same strength, until the fluid becomes somewhat 

 concentrated ; we thus get a bright blue solution of uroglaucin. 



To exhibit these substances in normal urine, the fluid must 

 be so far evaporated as just to remain liquid. On adding 

 concentrated nitric acid to the cold residue, a crystalline magma 

 of nitrate of urea is at once formed ; on adding to this a few more 

 drops of nitric acid (and sometimes even this is unnecessary) it 

 assumes a violet tint. If the crystalline mass is allowed to 

 stand for some time, and is then dissolved in the smallest 

 possible quantity of distilled water, after being left at rest for 

 some time, it deposits a sediment in which urrhodin and 

 uroglaucin may be detected either by the microscope or by ex- 

 traction with cold and then with boiling spirit. 



The action of nitrate of silver on uroxanthin is very singular. 

 On precipitating the chlorine by an excess of nitrate of silver, 

 from urine acidulated with nitric acid, and then carefully neu- 

 tralizing the filtered liquid by ammonia, there is not only a 

 pale yellow precipitate of phosphate of silver, but the fluid as- 

 sumes a brown tint, and in a short time there is likewise a 

 brown sediment. 



Heller has not yet succeeded in isolating uroxanthin. 



Uroglaucin associated with urrhodin, occurs in urinary se- 

 diments in Bright's disease, and in cases in which urine, 



