294 THE URINE. 



in alcohol, amyl alcohol, and chloroform, less readily so in water 

 and ether. 



Under pathological conditions still other pigments may be found 

 in the urine. These comprise haemoglobin and its derivatives, 

 haematin, methsemoglobin, and haematoporphyrin ; further, also uro- 

 rubrohaematin and urofuscohaematin, which are also undoubtedly 

 derived from haemoglobin, but which have thus far been found in 

 the urine on only one occasion ; further, the common pigments of the 

 bile ; and, finally, substances which belong to the class of the 

 so-called melanins. For a consideration of the various pathological 

 conditions under which the bodies may be met with, however, the 

 reader is referred to special works on diagnosis. At this place I 

 shall merely describe the more common tests by which their 

 presence can be demonstrated. 



The Blood-pigments. If the microscopical examination of the 

 urine shows the presence of red blood-corpuscles in the sediment, 

 further chemical examination is, of course, unnecessary. Cases of 

 simple haemoglobinuria, in contradistinction to haematuria, may occur, 

 however, in which dissolution of the haemoglobin has taken place in 

 the circulation already, and in which blood-corpuscles do not appear 

 in the urine. In such an event the demonstration of blood-pig- 

 ment can be made only by chemical methods. Its presence, it is 

 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 haemochromogen, which 

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

 chromogen can be readily demonstrated on spectroscopic exami- 

 nation (see page 330). When controlled in this manner, the test 

 is exceedingly sensitive, and may still yield a positive result even 

 when the chemical test by itself does not give a well-pronounced 

 reaction. 



SPECTROSCOPIC EXAMINATION. On direct spectroscopic exam- 

 ination the spectrum of methaemoglobin 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 



