298 DR. DAVY'S ACCOUNT OF SOME EXPERIMENTS ON THE BLOOD. 



and mercury was 42*5^ and the temperature was the same after the introduction of 

 three cubic inches of oxygen. The temperature of the room being 4/ °, a fire having 

 shortly before been lit, the vial was taken to an adjoining passage where the tempe- 

 rature of the air was 39°. Here the vial was well agitated, held in the hand with 

 thick gloves on as an additional protection. After about three quarters of a minute 

 the thermometer in the vial had risen a degree, viz. to 43*5. 



On the 14th of the same month a third experiment was made on venous blood from 

 the jugular vein of a Sheep. The vial was filled with 3*5 cubic inches of mercury 

 and eleven cubic inches of blood. The thermometer in the bottle, left five minutes, 

 was stationary at 49° ; the temperature of the mercurial bath was 49° ; the air of the 

 room was 52°; a thermometer with its bulb moistened was 45°, which I mention be- 

 cause the outer covering of the vial was moistened with some blood which had over- 

 flowed. After three cubic inches and a half of oxygen had been introduced, before 

 agitation, the thermometer was still 49°. The bottle was briskly shaken for about 

 half a minute ; now, on observing the thermometer, it was found at 50° ; the vial 

 was again agitated; there was no further increase of temperature: after ten minutes 

 it had fallen to 49°. 



I shall relate one experiment more, and that on arterial blood. It was made on 

 the 14th of February, and in the same manner as those on the venous blood. Before 

 and after the introduction of the oxygen, the blood, which was from the carotid artery 

 of the Sheep, was 45°; after agitation with oxygen it rose to 45*5 : this was done 

 when the temperature of the air was 39°. 



In a former part of this paper I proposed to recur to the question. Is the fixation 

 of oxygen in the blood attended with the formation of carbonic acid gas ? The change 

 of colour accompanying the fixation of oxygen by the blood, so different from that 

 produced by carbonic acid, and the effect of nitrous gas before and after, seem to be 

 most in favour of the idea, that the oxygen, in the first instance, is simply absorbed, 

 and that the heat evolved is merely the effect of its condensation ; or, that if any of 

 it enters into immediate union with the carbon, it is only a small part of the whole. 



VIII. Conclusion. 



Should the results detailed in the preceding pages be confirmed on repetition, they 

 can hardly fail having some effect on the theory of respiration and animal heat. 



As regards the former, they appear to me to tend to show that the lungs are ab- 

 sorbing and secreting, and perhaps exhaling organs, and that their peculiar function 

 is to introduce oxygen into the blood and separate carbonic acid from the blood. 



As regards animal heat, they appear to favour the idea, that it is owing, first, to the 

 fixation or condensation of oxygen in the blood in the lungs in conversion from ve- 

 nous to arterial ; and secondly, to the combinations into which it enters in the circu- 

 lation in connexion with the different secretions and changes essential to animal life. 



In illustration of what I imagine the secreting power of the lungs, I may mention 

 the difference of effects in an instance of death by strangulation, and another by ex- 



