128 



direct experiment. When Dr Girtanner injected 

 oxygen gas into the jugular vein of a dog, he cried 

 dreadfully, breathed quick, and died in three mi- 

 nutes : when nitrogen gas was thrown in, death 

 happened in 20 seconds *. Air, says M. Bichat, 

 thrown into the vascular system, quickly brings on 

 agitation, convulsions, and death f. By forcing air 

 through the windpipe into the lungs with a syringe, 

 and confining it there, he has made it to enter into 

 the blood-vessels, which immediately brings on agi- 

 tation and exertion in the animal ; and if an artery 

 in the leg or foot be now opened, the blood will 

 spring out frothy, and full of bubbles of air. If 

 hydrogen gas has been used, the bubbles may be in- 

 flamed ; and when this frothy blood has flowed 30 se- 

 conds, the actions of life cease, and cannot again be 

 restored, even although fresh air be supplied J. 



104. As the chief arguments in favour of the en- 

 trance of air into the blood, have been drawn from 

 the experiments of Mr Davy in his excellent " Re- 

 searches" into the nature and respiration of nitrous 

 oxide, it may, perhaps, be required that we should 

 notice the leading proofs which he adduces in favour 

 of it. Mr D. had found that hydrogen gas, when 

 inspired, only mingles with the air present in the 

 lungs, and is again thrown out unaltered with a 

 portion of the residual air ||. The bulk of this resi- 

 dual air, reduced to the temperature of 5J, he es- 



* Memoirs on Irritability, p. 221. 223. 



f Rechcrches sur la Vie et la Mort, p. 179. Ibid. p. 303. 



I! Researches, p. 39<). 



