PHYSICAL AND CHEMICAL AGENTS UPON BLOOD. 
699 
No. 27. — In 100 parts of air. 
Oxygen . . 2'10 
The analysis of the gas after twenty-four hours’ contact with the blood therefore stands 
thus : 
In 100 parts of air. 
Oxygen .... 2TCh 
n , . ., r n ITotal oxygen 7*21 
Carbonic acid . . 5T1J 
Nitrogen . . . 92*79 
As it is rather troublesome to carry the results of these analyses in the mind, I shall 
now give them in a tabular form, when it will be at once evident to any one who has 
given attention to the subject, that the chemical changes exerted upon air by putrefac- 
tion, in so far as they are here studied, are very different from the true respiratory ones 
previously alluded to. 
In 100 parts of air. 
Oxygen. 
Carbonic acid. 
Nitrogen. 
1st portion 
of fresh blood 
13-76 
2-05 
84-19 
2nd 
same „ 60 hours old ... 
2-88 
3-69 
93-43 
3rd 
„ „ 136 „ 
1-01 
4-31 
94-68 
4th „ 
„ „ 184 
0-00 
4-91 
95-09 
5th „ 
„ 304 
— 
4-99 
— 
6th „ 
„ „ 688 
— 
5-11 
— 
It is here seen that the process of putrefaction exerts, up to a certain extent, the same 
effect on the absorption of oxygen and exhalation of carbonic acid by the constituents 
of the blood, as was observed to be exercised by an increase of temperature. Thus we 
find that the older the blood becomes the more oxygen it extracts from the air, and the 
more carbonic acid does it at the same time yield. Here, however, the analogy stops. 
For we find that while in those cases where the normal respiratory action is such as to 
have produced the exhalation of more than 5 per cent, of carbonic acid, the oxygen 
does not entirely disappear from the air (see experiments 35 and 58, Part II.), and in 
those again where the oxygen has been entirely taken up by the blood it is again all 
returned to the atmosphere, as seen in the results of experiment 14 related at page 695. 
During the putrefactive process, on the other hand, the amount of oxygen absorbed is 
exceedingly great in proportion to the quantity of carbonic acid exhaled. 
Part II.— INFLUENCE OF CHEMICAL AGENTS ON THE BLOOD. 
Effect of Animal Peoducts. 
Snake Poison. 
For the purpose of studying the effect of animal poisons upon the reciprocal action of 
blood and atmospheric air, I obtained, through the kindness of the late Mr. Mitchell, 
