452 An Account of some Experhnerits on Animal Heal. 



circumstances, is difficult to be accomplished ; whilst the formes 

 is comparatively easy, and in a theoretical point of view is pro- 

 bably equally useful. 



I have employed both the methods commonly used. . I shall 

 mention most of the experiments that I have made, without 

 noticing the repetitions of them, and shall begin with those on 

 the times of cooling of equal volumes of venous and arterial 

 blood. 



The blood used was from the jugular vein and the carotid 

 artery of a lamb about four months old. It was received in 

 bottles; and to remove the fibrin, which is a great impediment 

 in experiments of this kind, it ^^as immediately stirred with a 

 wooden rod. In respect to colour, the difference between the 

 venous and arterial blood was not so great as in the sheep's ; and 

 this in a great variety of instances I have always observed^ the 

 venous being of a less dark hue. The specific gravity of the 

 venous blood, without the fibrin, was found to be 1050, and that 

 of the Efrterial 1047. 



A glass bottle equal in capacity to 25 IS grains of water, and 

 weighing 1332 grains, was filled respectively with water ancl 

 venous and arterial blood of the temperature of the room 62,, 

 about four hours after the blood had been drawn, during which 

 time each bottle had been closely corked. A delicate thermo- 

 meter, by means of a perforated cork, was placed in the middle 

 of the liquid. The bottle was then plunged into water of the 

 temperature 140 Fahrenheit; and when the mercury had risen to 

 120, the bottle was quickly wiped and suspended in the middle 

 of the room, and the progress of cooling was noticed every five 

 minutes, till the thermometer had fallen to 80. The fuUpwing 

 were the general results obtained : 



Water cooled from 120 to 80 in 91 minutes 



Arterial blood in 89 



Venous blood in 88 



Considering therefore the capacity of water for heat to be denoted 

 by 1000, neglecting the effect of the glass bottle producing a 

 difference only of about half a minute, and the same in each in- 

 stance, and dividing the times of cooling by the specific gravity, 

 the relative capacities of venous and arterial blood without 

 fibrin appear to be as -921 and -934. 



In the following experiments the same kind of blood and the 

 same quantity was used as in the preceding. The mixtures were 

 made in a \ery thin glass receiver containing a delicate ther- 

 inouTetcr. The tem])erature of the room was 56. 



Hot water temperature 121 ; cold water 61. Mixture of the 

 two 90, after two minute? 89, after three 88, and after eight 87. 



Venous 



