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



The effect of the absorption of the gas to perfect saturation was on the arterial and 

 venous blood the same ; it rendered both very dark ; the serum it rendered more 

 liquid, which was well marked by diminished tendency to froth on agitation. 



I shall now proceed to notice the trials which I have instituted of agitating blood 

 and serum, to which a known quantity of carbonic acid had been added, with one or 

 more of the gases considered by Dr. Stevens as exerting an attraction on carbonic 

 acid, and by that means expelling it. 



From the experiments which I have made on serum, it appears in its healthy state 

 incapable of absorbing oxygen, or of immediately furnishing carbon to form carbonic 

 acid ; and in no instance in which I have agitated it with common air or with hy- 

 drogen, when obtained from the blood of a healthy animal, has there been any indi- 

 cation of the disengagement of gas; it therefore is peculiarly well fitted for the trial 

 in question. 



To nine cubic inches of serum from the mixed blood of the Sheep/one cubic inch 

 more of serum was added, containing a cubic inch of carbonic acid, with which it 

 had been impregnated over mercury. The mixture of the two was introduced into 

 the double-mouthed bottle without delay, and well agitated with twenty-two cubic 

 inches of common air. On turning the stop-cock there was no change of volume. 

 The serum was transferred, and there was added to it, with as little motion as pos- 

 sible, another cubic inch of serum, containing the same quantity of carbonic acid. 

 Now poured back into the bottle and agitated, on opening the stop-cock a little air 

 was disengaged ; it was collected and found equal to --5-jrths cubic inch. The serum 

 was left exposed to the action of the air in the bottle over night, the stop-cocks closed ; 

 the following morning on opening the stop-cock of the bent tube no air was expelled; 

 on the contrary, there was a just perceptible rise of water in it. The experiment was 

 carried further: the serum was transferred to a vial and closed, and the double- 

 mouthed bottle was filled with hydrogen. The serum was returned and well agitated 

 with the hydrogen. On turning the stop-cock -}-^ths of a cubic inch of air was ex- 

 pelled. It was agitated a second time without further expulsion of air, and left in 

 contact with hydrogen for more than twelve hours without any further effect. Thus 

 it appears that of the two cubic inches of carbonic acid gas introduced into the serum, 

 only one-fifth of a cubic inch was expelled by successive agitation with atmospheric 

 air and with hydrogen. 



One cubic inch of venous blood of a Man which had absorbed 1*2 cubic inch of 

 carbonic acid, was mixed with twelve cubic inches of similar blood, and agitated with 

 hydrogen in the double-mouthed bottle. A very little air only was expelled, viz. 

 -j^^ths cubic inch. 



To fifty-five measures (1*1 cubic inch) of venous blood of a Sheep, twenty measures 

 of gas were added over mercury, composed of about equal parts of oxygen and car- 

 bonic acid. After agitation about seventeen measures were absorbed, and the blood 

 had acquired a florid hue ; ten measures more of oxygen were added ; there was no 



