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



in venous blood; that it may be expelled by oxygen or by hydrogen, although not 

 by the air-pump; and he supposes that the difference of effect is owing to a peculiar 

 attraction for carbonic acid exercised by these gases. 



To endeavour to resolve my doubts on this important point, I have had recourse 

 to the apparatus already mentioned, viz. the graduated tube with the mercurial pneu- 

 matic trough, and the double-mouthed bottle furnished with stop-cocks, &c. as being 

 well adapted for simple and decisive experiments. 



By means of the graduated tube I have agitated venous blood in hydrogen over 

 mercury, as about a cubic inch of each, and other proportions, and have left the 

 blood exposed to the influence of the gas for several hours ; and I have made similar 

 trials with it, using larger quantities in the double- mouthed bottle, as sixteen cubic 

 inches of each, and also other proportions ; the results have been either of the same 

 negative character, or, if different, indicating only the disengagement of carbonic acid 

 gas in an extremely minute quantity. In all the experiments with* the graduated tube 

 in which fresh blood was used, whether of Man or of the Sheep, the fibrin displaced 

 out of the contact of the air, on agitation with hydrogen, there was no sensible in- 

 crease of the volume of the gas, and no diminution of it when it was transferred to, 

 and shaken with, lime-water. And in the best experiments, on a larger scale, with 

 the double-mouthed bottle, when most attention was paid to all the circumstances 

 likely to insure accuracy, as in the first instance the exclusion of air from the blood, 

 and in the second the having it of the temperature of the bottle and of the room, 

 the results have been similar, and of a negative character. I shall describe a small 

 number of experiments, those, the results of which appeared least ambiguous. 



Seven cubic inches of Sheep's blood from the jugular vein, its fibrin broken up by 

 agitation with lead whilst coagulating, out of contact with air, and cooled under 

 water, were agitated with hydrogen (twenty-five cubic inches), previously well washed 

 with lime-water, and which, tested by lime-water, after this precaution were found 

 perfectly free from carbonic acid. On turning the stop-cock of the bent tube con- 

 nected with distilled water, no change of volume was indicated, and the blood was 

 agitated again with the same result. By means of the perpendicular tube distilled 

 water was admitted, and some of the gas expelled ; first a cubic inch into a graduated 

 tube filled with lime-water, and next about four cubic inches into a vial filled with 

 distilled water, and in which afterwards a little lime-water was added to the gas ; in 

 neither could any traces of carbonic acid be detected ; the lime-water remained trans- 

 parent. 



Ten cubic inches of venous blood, taken by a large orifice from the arm of a young 

 Man threatened with haemoptysis, the fibrin broken up in the same manner as the 

 last, and rapidly cooled under water in a running stream to the temperature of the 

 room, 51°, were similarly treated with hydrogen, and with precisely the same result ; 

 after having been twice well shaken, on turning the stop-cock, there was no change 

 of volume. The blood was kept in contact with the hydrogen over night, the stop- 



