

THE BLOOD GASES. 43 



minimal amount, and does not exceed what distilled water at the temperature of 

 the body would take up at the partial pressure of the O in the air of the lungs 

 (Lothar Meyer). 



(b) Almost the total of the blood is chemically united, and therefore not subject 

 to the law of absorption. It is loosely united to . the haemoglobin of the red 

 corpuscles, with which it forms oxyhsemoglobin ( 15). With regard to the taking 

 up of O, the total quantity of blood behaves exactly like a solution of haemoglobin 

 free from O (Preyer). The absorption of O is more rapid in blood than in a 

 solution of Hb. 



The absorption of this quantity of is completely independent of pressure ; hence, animals 

 confined in a closed space, until they are nearly asphyxiated, can use up almost all the from 

 the surrounding atmosphere. The fact of the union being independent of pressure is proved by 

 the following ; The blood only gives off copiously its chemically united when the atmo- 

 spheric pressure is lowered to 20 millimetres, Hg ( Worm Mutter) ; and, conversely, blood only 

 takes up a little more when the pressure is increased to 6 atmospheres {Bert). 



Physical Methods of obtaining from Blood. Notwithstanding the chemical 

 union between the Hb and O, all the O of the blood can be expelled from its state 

 of combination by those means which set free absorbed gases (a) by introducing 

 blood into a Torricellian vacuum ; (b) by boiling ; (c) by the conduction of other 

 gases [H, N, CO, or NO] through the blood, because the oxyhsemoglobin compound 

 is so loose that it is decomposed even by these physical means. 



Reducing Reagents. Amongst cJiemical reagents the following reducing 

 substances ammonium sulphide, sulphuretted hydrogen, alkaline solutions of sub- 

 salts or Stokes's fluid, iron filings, &c, rob blood of its O ( 15). 



Relation to Fe. The amount of iron in the blood (0'55 in 1000 parts) stands in direct relation 

 to the amount of Hb ; this to the quantity of blood-corpuscles ; and this, in turn, to the specific 

 gravity of the blood. The amount of in the blood, therefore, is nearly proportional to the 

 specific gravity of the blood, and it is also in proportion to the amount of iron in the blood. 

 Picard affirms that 2 "36 grams of iron in the blood can fix chemically 1 gram ; while, 

 according to Hoppe-Seyler, the proportion is 1 atom iron to 2 atoms 0. 



During morphia narcosis the amount of O in the blood is diminished {Ewald) ; after haemor- 

 rhage the arterial blood is saturated with O {J. G. Ott). 



Disappearance of in Shed Blood. Even immediately after blood is shed, there is a slight 

 disappearance of O, as a physiological index of respiration of the tissues within the living blood 

 itself ( 132). "When blood is kept long outside of the blood-vessels, the quantity of gradually 

 diminishes, and if it be kept for a length of time at a high temperature it may disappear 

 altogether. This depends upon decomposition occurring in the blood, wherebj^ reducing sub- 

 stances are formed which consume the 0. All kinds of blood, however, do not act with equal 

 energy in consuming 0, e.g., venous blood from active muscles acts most energetically, while 

 that from the hepatic vein has very little effect. C0 2 appears in the blood in place of the 0, 

 and the colour darkens. The amount of C0 2 produced is sometimes greater than that of the 

 consumed. 



Relation to Acids. If blood (or a solution of oxyhsemoglobin) be acted upon by acids {e.g., 

 tartaric acid) until it is strongly acid, can be pumped out in considerably less amount, while 

 the formation of C0. 2 is not increased. We must, therefore, assume that, during the decomposi- 

 tion of the Hb caused by the acids ( 18), a decomposition product becomes more highly oxidised 

 by the intense chemical union of the at the moment of its origin {Lothar, Meyer, Zuntz, 

 Strassburg). The same phenomenon occurs when oxyhsemoglobin is decomposed by boiling. 



37. IS OZONE PRESENT IN BLOOD ? On account of the numerous and 

 energetic oxidations which occur in connection with the blood, the question has 

 often been raised as to w r hether the O of the blood exists in the form of ozone (0 3 ). 

 Ozone, however, is contained neither in the blood itself (Schonbein) nor in the 

 blood-gases obtained from it. Nevertheless, the red corpuscles (and Hb) have a 

 distinct relation to ozone. 



(1) Tests for Ozone. Haemoglobin acts as a conveyer of ozone, i.e., it is able to remove the 

 active of other bodies and to convey or transfer it at once to other easily oxidisable substances. 

 {a) Turpentine which has been exposed to the air for a long time always contains ozone. The 

 tests for the latter are starch and potassium iodide, the ozone decomposing the iodide, when the 

 iodine strikes a blue with the starch, {b) Freshly-prepared tincture of guaiacum is also rendered 



