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no such conclusion j and it is not a little remarkable 
that this philosopher, who had before so well obser- 
ved the reciprocal effects produced in the air, when it 
thus changed the colour of the blood *, should, in 
these experiments, have entirely overlooked them* 
It is still more remarkable, since these experiments 
have drawn so much attention, and seem now to be 
the chief or only remaining evidence urged in sup- 
port of the hypothesis of cxygenation, that some at- 
tempt has not been made to inquire farther into the 
actual circumstances which attend them. It is this 
examination which we now propose to make, in the 
hope, vhat, if it do not lead us to a knowledge of the 
true cause of this phenomenon, it may at least serve to 
shew to what it is not to be ascribed. 
584. With this view, we procured a quantity of 
black blood, and putting it into a sheep's bladder, 
suspended it from the top of a jar containing about 
100 cubic inches of atmospheric air. The jar was 
inverted in a saucer containing mercury, and within 
it a small cup of solution of potassa was likewise 
placed. The blood, in a short time, assumed a florid 
hue, and a dimness extended over the inside of the 
jar. By the next day, the mercury in the saucer 
had risen ^ of an inch into the jar, and it continued 
to rise several days ; so that, by the fifth day, it had 
reached nearly to an inch in height. The jar was 
then raised, and diluted acid being poured upon the 
alkaline solution, disengaged from it a large quanti* 
ty of carbonic acid gas. By this experiment, there- 
* Obs, on Air, vol. iii, p. 33(7. 
