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



the carotid artery, agitated with thirty-three measures of common air, produced a 

 diminution of two measures ; and sixty-three of the same arterial blood, agitated with 

 thirteen of pure oxygen, a diminution of three ; whilst sixty-three of venous blood 

 from the jugular vein of the same animal, agitated with thirty-three of common air, 

 produced a diminution of six ; and seventy of this blood, with thirteen of oxygen, 

 a diminution of eight*. 



In experiments on a larger scale, using the double-mouthed bottle, in which about 

 ten cubic inches of blood were agitated with about twenty-two cubic inches of air, 

 the results were in accordance with the preceding. Thus when the arterial blood of 

 the Sheep was agitated with common air and with oxygen, on turning the stop-cock 

 of the bent tube there was an absorption in one instance of about '3 cubic inch, and 

 in the other of about '4 cubic incjh ; and, with venous blood, in the instance of com- 

 mon air, of about 1* cubic inch, and in that of oxygen, of about 1-25 cubic inch. 



These experiments were all made on the blood of the same animal. In experiments 

 on the blood of different individuals of the same species of animal, and on the blood 

 of animals of different species, the results have varied in regard to the degree of ab- 

 sorption, and remarkably so in the instance of the blood of man. 



In every instance the absorption or disappearance of a portion of the air has been 

 attended with some change in the colour of the blood; the venous has invariably ac- 

 quired the florid vermillion hue of arterial blood, and the arterial has had its florid 

 hue heightened. 



The air that has been absorbed or which disappears, when atmospheric air has 

 been used, in accordance with the commonly received opinion and the results of 

 Dr. Christison's experiments'}-, has been found to be oxygen. 



Relative to the residual air, when pure oxygen has been used, whether on the 

 smaller or larger scale of experiment, no carbonic acid gas has been detected in it in 

 the most carefully conducted trials. When common air has been employed, then a 

 trace of this acid gas has been found in the residual air after agitation with the blood, 

 but not exceeding 1 per cent, at a temperature between 40° and 50°. I shall notice 

 in detail an experiment with each, as the results are of consequence. 



Ten cubic inches of venous blood (its fibrin displaced) from the jugular vein of a 

 Sheep, rapidly cooled, were agitated in twenty-two cubic inches of oxygen gas, which 

 had been well washed with lime-water. After an absorption equal to about one cubic 

 inch, some of the gas was expelled and passed into lime-water, the transparency of 

 which it did not in the slightest degree impair. 



The same quantity of similar blood was similarly treated with common air, which 



* Notwithstanding the frothing attending the agitation of blood in air, the absorption or diminution of vc 

 lume was ascertained with tolerable accuracy by observing the rise of the mercury in the tube. The experi- 

 ments were made as nearly as possible under ordinary atmospheric pressure, which was easily effected, as the 

 mercurial pneumatic trough used exceeded in depth the length of the tube. 



t Edinburgh Medical and Surgical Journal, vol. xxxv. p. 94. 



