upon the Anmal System, 1^ 



and directing my experiments exclusively to their physiological 

 tendency, I instituted similar researches into the effects of 

 other gases, as I considered that such a comparative inquiry 

 was wanting to complete the ultimate objects to wliich my 

 attention was directed ; although I am aware that this latter 

 ground is already so well cultivated by others as to render it 

 almost unnecessary to go over it myself. 



I. EXPERIMENTS WITH NITROUS OXIDE GAS. 



Having carefully prepared some nitrous-oxide over night, in 

 order that it might become purified by standing upon water, 

 the following morning 1 placed a stout healthy kitten under 

 the glass vessel containing the gas, the animal being raised 

 above the water, and with other precautions, as practised in the 

 experiments with oxygen. The effects of the gas were soon 

 apparent, and in a little more than a quarter of an hour the 

 kitten fell on its side quite motionless, having breathed quick 

 and staggered to and fro at the least efforts to move. Being 

 taken from the vessel, it gradually recovered in the open air, 

 and regained its strength in the course of the evening. Another 

 kitten of the same brood, about a fortnight old, was similarly 

 affected in the gas, and having remained half an hour under 

 the glass, did not recover in this open air. The temperature of 

 the atmosphere was that of an ordinary summer's day. The 

 animal was immediately opened, when the blood was found to 

 be universally florid and more transparent than commonly, — 

 the vessels of the brain, pleura, and lungs, being highly 

 injected. 



Some sparrows lived only four or five minutes in nitrous 

 oxide, breathing rapidly; and on being opened they exhibited 

 the same florid appearance and highly injected membranes. 

 The heart in each was found palpitating. 



A frog being placed under a glass jar of this gas, did not seem 

 to be affected in any way ; but in the morning it was found 

 dead, and the blood vessels were found injected throughout. 

 Some mice were immersed in vessels of this gas, and were 

 almost immediately affected with a staggering and hurried 

 breathing. They lived about seven or eight minutes; and on 

 being examined, the heart was found palpitating in each. A 



