THE BLOOD 73 



ent gas through, or by the addition of a reducing substance, as, for 

 example, an ammoniacal ferrotartrate solution (STOKES' reduction- 

 liquid). If an oxyhaemoglobin solution or arterial blood is kept 

 in a sealed tube, we observe a gradual reduction of the oxyhaemo- 

 globin into haemoglobin. If the solution has a proper concentration, 

 a crystallization of haemoglobin may occur in the tube at lower 

 temperatures (HUFNER). 



Carbon Monoxide Haemoglobin is the molecular combination be- 

 tween 1 mol. haemoglobin and 1 mol. CO. This combination is 

 stronger than the oxygen combination of haemoglobin. The oxygen 

 is for this reason easily driven off by carbon monoxide, and this ex- 

 plains the poisonous action of carbon monoxide, which kills by the 

 expulsion of the oxygen of the blood. 



Carbon monoxide haemoglobin is formed by saturating blood or 

 a haemoglobin solution with carbon monoxide, and may be obtained 

 as crystals by the same means as oxyhaemoglobin. These crystals 

 -are isomorphous to the oxyhaemoglobin crystals, but are less soluble, 

 more constant, and their bluish-red color is more marked. For the 

 detection of carbon monoxide haemoglobin its absorption spectrum 

 is of the greatest importance. This spectrum shows two bands which 

 are very similar to those of oxyhaemoglobin, but they occur more 

 towards the violet part of the spectrum. These bands do not change 

 noticeably on the addition of reducing substances; this constitutes 

 an important difference between carbon monoxide and oxyhaemo- 

 globin. If the blood contains oxyhaemoglobin and carbon monoxide 

 haemoglobin at the same time, we will obtain on the addition of a 

 reducing substance (ammoniacal ferrotartrate solution) a mixed 

 spectrum originating from the haemoglobin and carbon monoxide 

 haemoglobin. 



A great many reactions have been suggested for the testing of 

 carbon-monoxide haemoglobin in medico-legal cases. A simple 

 and at the same time a good one is HOPPE-SEYLER'S soda test. 

 The blood is treated with double its volume of caustic-soda solution 

 of 1.3 sp. gr., by which ordinary blood is converted into a dingy 

 brownish mass, which when spread out on porcelain is brown 

 with a shade of green. Carbon-monoxide blood gives under the 

 same conditions a red mass, which if spread out on porcelain 

 shows a beautiful red color. Several modifications of this test have 

 been proposed. 



in* 17 ER SIT 71 



