460 RESPIRATION. 



More recently, Bernard has shown that for a certain time 

 after the blood is drawn from the vessels, it will continue to 

 consume oxygen and exhale carbonic acid. If all the car- 

 bonic acid be removed from a specimen of blood, by treating 

 it with hydrogen, and it be allowed to stand for twenty-four 

 hours, another portion of gas can be removed by again treat- 

 ing it with hydrogen, and still another quantity by treating 

 it with hydrogen a third time. 1 



From these facts it is clear that, in the experiment of 

 Magnus, the excess of carbonic acid involved a post-mortem 

 consumption of oxygen ; and no analyses made in the ordi- 

 nary way, by displacement with hydrogen, or by the air- 

 pump, in which the blood must necessarily be allowed to 

 remain in contact with oxygen for a number of hours, can be 

 accurate. The only process which can give us a rigorous 

 estimate of the relative quantities of oxygen and carbonic 

 acid in the blood is one in which the gases can be estimated 

 without allowing the blood to stand, or in which the forma- 

 tion of carbonic acid in the specimen, at the expense of the 

 oxygen, is prevented. All others will give a less quantity of 

 oxygen and a greater quantity of carbonic acid than exists in 

 the blood circulating in the vessels, or immediately after it is 

 drawn from the body. 



A solution of this important and difficult problem in analy- 

 sis of the blood has been accomplished by Bernard. This ob- 

 server made a great number of experiments, in the hope of dis- 

 covering some means by which the consumption of oxygen by 

 the blood-corpuscles could be arrested. 2 He found, finally, that 

 carbonic oxide, one of the most active of the poisonous gases, 

 had a remarkable affinity for the blood-corpuscles. When 



1 BERNARD, Lemons sur les Proprietes Physiologiques et les Alterations Patholo- 

 yiques dcs Liquulcs de V Organisme, Paris, 1859, tome i., p. 354 et seq, 



2 Harley (pp. cit., p. 334) ascertained that a few drops of chloroform, added to 

 the fresh blood, greatly diminished the activity of the change of oxygen into car- 

 bonic acid. It did not entirely arrest it, however, and the author does not sug- 

 gest its use in quantitative analyses for gases. 



