On Respiration. 425 



78 parts hydrogen, and 22 oxygen, for more than an hour, 

 v/ithout suffering any apparent inconvenience. 



5. That the excitability of an animal is much diminished 

 when he breathes any considerable proportion of hydrogen 

 gas, or that it at least has a tendency to produce sleep. 



6. That there is reason to presume an animal evolves less 

 carbonic acid gas during its sleeping, than in its waking 

 hours. 



7. That the lungs of a middle-sized man contain mors 

 than 100 cubic inches of air after dcatli. 



These experiments have been conducted without refe- 

 rence to any particular theory, and indeed some of the re- 

 sults were so contrary to our preconceived opinions, that 

 we have been induced to bestow more thaji ordinary atten- 

 tion on the subject. Confideat, however, that all those 

 who repeat the experiments with the same care uiil arrive 

 at the same results, we shall rest satisfied with stating the 

 facts, not without a hope that those brilliant discoveries of 

 Professor Davy, which have already given us new views uf 

 the operations of nature, will in iheir progress furnish us 

 with that explanation which it is in vain to expect at pre- 

 sent. 



Azote or nitrogen, for instance, has been considered as a 

 simple or elementary substance; it is recognised, however, 

 principally by negative properties. A very gaseous fluid 

 which will not support life or combustion, which is not 

 absorbed by water, nor acted upon by the tests for oxygen, 

 nor capable of being detonated with oxygen gas, is generally 

 pronounced to be azote: it is the constant residuum in 

 almost all our experiments u[)on gases, but who shall say 

 whether this residuum is a simple substance or a com- 

 pound ? 



The experiment of Professor Bcrzelius leads us to sus- 

 pect it of metallic projicrtics ; and those of Davy make it 

 probable that it is an oxidated body, the subject is still un- 

 der discussion. But we may fairly indulge more than a 

 hope that the ardent zeal and well-directed labours of the 

 philosopher:? just mentioned will throw a new and impor- 

 tant light upon this obscure and ditficult subjecL 



LXIII. Dff- 



