THE PIGMENTS OF THE URINE. 311 



true, is usually indicated by the color of the urine, but this may 

 be simulated by other substances as well. 



HELLER'S TEST. This is the most convenient test for demon- 

 strating the presence of blood-pigment in the urine, and, in the modi- 

 fication here given, exceedingly sensitive. It is based upon the 

 decomposition of the pigment in question by means of caustic 

 alkali and the resulting formation of haemochromogen. To this 

 end, a small amount of the urine, or, still better, of the sediment, is 

 rendered strongly alkaline with caustic alkali and boiled. On stand- 

 ing, the precipitated earthy phosphates settle to the bottom, and are 

 colored a more or less intense carmin by the hsemochromogen, which 

 has likewise separated out. That the pigment is in reality hsemo- 

 chromogen can be readily demonstrated on spectroscopic exami- 

 nation. When controlled in this manner, the test is exceedingly 

 sensitive, and may still yield a positive result even when the chem- 

 ical test by itself does not give a well-pronounced reaction. 



SPECTROSCOPIC EXAMINATION. On direct spectroscopic exam- 

 ination the spectrum of methsemoglobin is usually obtained. The 

 urine should first be acid, and if necessary a little acetic acid is 

 added. On the addition of a little ammonia and ammonium sul- 

 phide and subsequent filtration the broad band of haemoglobin is then 

 obtained. With oxyhsemoglobin, on the other hand, the two bands 

 between D and E are observed ; and upon the subsequent addition 

 of ammonia and ammonium sulphide and filtration the spectrum of 

 reduced haemoglobin results. If this does not appear distinctly, the 

 solution is treated with an excess of sodium hydrate solution, and 

 will then give the spectrum of hsemochromogen. 



Haematin. Hsematin is very rarely found in the urine. Its 

 presence as such can be determined only by spectroscopic examina- 

 tion. Like haemoglobin and methaemoglobin, it gives Heller's 

 reaction. 



Haematoporphyrin. According to Garrod, traces of haematopor- 

 phyrin may be found in every urine. Larger quantities are 

 observed in a number of diseases, but even in these the amount 

 is usually so small that its presence will scarcely be suspected 

 from simple inspection. Typical haematoporphyrintiria, on the 

 other hand, may be observed following the prolonged administra- 

 tion of sulphonal, trional, and tetronal, or in cases of poisoning with 

 the substances in question. The urine then appears dark red in 

 color, and on standing may turn almost black. As Hammarsten 

 has pointed out, this change in color is only in part due to haemato- 

 porphyrin, and is largely referable to other red and reddish-brown 

 pigments of unknown character. Whether or not different haemato- 



?orphyrins exist has not been definitely determined, but is probable, 

 n freshly voided urines haematoporphyrin probably exists in com- 

 bination with some other, still unknown body, with which it forms 

 a colorless chromogen. From this the free pigment then develops 

 on exposure to the air. 



