ON HEAT GENERATED IN THE BLOOD. 143 



temperature of the contained fluid. It was, therefore, obvious that any heat- 

 ing which might occur in the process of tilting or shaking in subsequent 

 experiments could not be referred to the mechanical work expended in the 

 tube and its contents. 



My next experiments consisted in determining whether, when agitated 

 with a neutral gas, as, for example, hydrogen, any material change in the 

 temperature of the blood occurred ; they led to the result that when agi- 

 tated with hydrogen gas no heating of the blood results, it being always 

 remembered that the mechanical agitation to which the blood and the 

 neutral gas were subjected was the same as in my experiments with blood 

 and oxygen. 



In ray systematic experiments on the heat generated during the process 

 of arterialization, the following observations were always made : — 



1. The temperature of the lower as contrasted with the upper vessel was 

 determined after the latter had been exhausted. 



2. The temperature- observations were repeated after shaking with hy- 

 drogen. 



3. After the renewal of a vacuum. 



4. After admission of oxygen in the mixing-vessel. 



5. After oxygen had been thoroughly shaken with the blood. 



The results of my experiments on veiy numerous samples of venous blood 

 have led to the conclusion that whilst, as I have previously mentioned, no 

 heat is evolved on agitating blood with hydrogen, there is, on agitation with 

 oxygen, always a slight evolution of heat. 



To determine the exact heating, when venous blood of varying gaseous 

 composition is arterialized, appears to be most desirable. We should espe- 

 cially attempt to determine the heating observed when the average venous 

 blood contained in the right ventricle and directly drawn from it is ar- 

 terialized. The first and most important datum to be ascertained appeared 

 to me, however, to be the heating which takes place when blood which has 

 been thoroughly reduced, i. e. which contains no loosely combined oxygen 

 and exhibits Stokes's spectrum, is completely arterialized. 



From five sets of experiments on the heat developed during the arteriali- 

 zation of perfectly reduced blood, I arrived at the conclusion that the mean 

 rise of temperatiire during the absorption of oxygen amounted to 0°-0976 C. 

 The maximum heating found was 0°'lll C, and the minimum 0°-083C. 



The research, of which the above are the results, was conducted in the 

 Physical Laboratory of the University of Edinburgh ; and I have to express 

 my thanks to Professor Tait for the uniform kindness with which he helped 

 me by advice, assistance, and apparatus in ascertaining the facts which are 

 recorded in this Report. I intend to extend these researches very greatly. 

 It is most desirable that in future experiments venous blood of known com- 

 position be employed, and that the amount of oxygen absorbed and CO^ 

 evolved be ascertained after each experiment. I propose likewise to increase 

 the period during which the blood is agitated, making use of an arrangement 

 whereby the mechanical work performed in the agitation may be precisely 

 determined. 



