24 CARBONIC OXIDE-HEMOGLOBIN. 



(h'oiralcicsky). It crystallises if defibrinated blood is shaken with amyl nitrite and the 

 mahogany-brown laky fluid be allowed to evaporate slowly (Halliburton). 



If a trace of ammonia be added to a solution of methaemoglobin, it gives an alkaline solution 

 of methiemoglobin, which shows two bands like oxyhemoglobin, of which the first one is the 

 broader, and extendi more towards the red. If ammonium sulphide be added to the methsemo- 

 globin solution, reduced Hb is formed. 



[Action of Nitrites. The addition of amyl nitrite dissolved in alcohol, or sodic 

 or potassic nitrite to defibrinated blood causes the latter to assume a chocolate 

 colour, which, on the addition of ammonia, changes to red. The chocolate-coloured 

 fluid shows one well-defined band in the red, and less distinctly other three bands like 

 methaemoglobin (Gamgee).] 



[The nitrites therefore form a compound with its oxygen more firmly fixed than the in 



HbO. so that large doses of nitrites arrest the internal respiration and are poisonous. It is, 



however, affected by the products formed in the blood during asphyxia, while CO-Hb is not, 



the methamioglobin formed by the nitrites is reduced by these products to Hb, which as it 



a through the lungs takes up 0.] 



16. CARBONIC OXIDE-HJEMOGLOBIN, POISONING WITH CO. 3. CO- 



Haemoglobin is a more stable chemical compound than the foregoing, and is pro- 

 duced at once when carbonic oxide is brought into contact with pure Hb or 2 Hb 

 (CI. Bernard, 1857). It has an intensely florid or cherry red colour, is not dichroic, 

 and its spectrum shows two absorption-bands, very like those of 2 Hb, but they 

 are slightly closer together and lie more towards the violet (fig. 17, 3). Reducing 

 substances which act upon HbO. e.g., ammonium sulphide or Stokes's fluid, do not 

 affect these bands, i.e., they cannot convert the CO-Hb into reduced Hb. If a 10 

 per cent, solution of caustic soda be added to a solution of CO-Hb, and heated, it 

 gives a cinnabar red colour ; while, with an Hb0 2 solution, it gives a dark brown, 

 greenish, greasy mass. Oxidising substances [solutions of potassic permanganate 

 (0O'2ii per cent.), potassic chlorate (5 per cent.), and dilute chlorine solution] make 

 solutions of CO-Hb cherry red in colour, while they turn solutions of 2 Hb pale 

 yellow. After this treatment both solutions show the absorption bands of methse- 

 mogoblin, but those of the CO-Hb appear considerably later. If ammonium 

 sulphide be added, 0.,Hb and CO-Hb are re-formed. 



On account of its stability, CO-Hb resists external influences and even putrefaction for a long 

 time, and the two bamls of the spectrum may be visible after many months. Landois obtained 

 the soda test and spectroscopic bands in the blood of a woman poisoned eighteen months pre- 

 viously by CO, and after great putrefaction of the body had taken place. [Stirling has kept 

 CO-Hb in a stoppered bottle for five years without putrefaction taking place.] 



If CO or air containing it be inspired, it gradually displaces the O, volume for 

 volume, out of the red blood-corpuscles, and death soon occurs ; 1000 c.cm. inspired 

 at once will kill a man. A very small quantity in the air (^^"tt^o-o") suffices, in 

 a relatively short time, to form a large quantity of CO-Hb. As continued contact 

 with other gases (such as the passing of O through it for a very long time) 

 gradually separates the CO from the Hb, with the formation of 2 Hb, it happens 

 that, in very partial poisoning with CO, the blood gradually gets rid of the CO by 

 the respiratory organs. It is uncertain if any part is excreted as C0 2 . [CO- 

 Haemoglobin, being a stable compound when once formed, circulates in the blood- 

 vessels ; but it neither gives up oxygen to the tissues, nor takes up oxygen in the 

 lungs, hence its very poisonous properties. The real cause of death in animals 

 poisoned with it is, that the internal respiration is arrested.] 



Poisoning with Carbonic Oxide. Carbonic oxide is formed during the incomplete combustion 

 of coal or coke, and passes into the air of the room, provided there is not a free outlet for the 

 products of combustion. It occurs to the extent of 12-28 per cent, in ordinary gas, which 

 largely owes its poisonous properties to the presence of CO. If the O be gradually displaced from 

 the blood by the respiration of air containing CO, life can only be maintained as long as suffi- 

 cient O can be obtained from the blood to support the oxidations necessary for life. Death 

 occurs before all the O is displaced from the blood. CO has no effect when directly applied to 

 muscle and nerve. When it is mixed with air, ns in coal-gas poisoning, and inhaled, there is first 



