£20 Letter to Governor Powiudl 



the outer coat of the lungs with the slender point of a sharp 

 penknife, and by a constant blast made with a double pair 

 of bellou-s he kept the lungs always distended and without 

 motion ; and it was observed, that while the lungs were thus 

 kept distended with a constant supply of fresh air, the dog 

 lay still, his eves were quick, and Ids heart beat regularly ; 

 but that upon leaving off blowing, and suffering the lungs 

 to subside and lie still, the dog presently fell into dying 

 convulsive motions, and as soon recovered again on renew^- 

 ing the blast, and supplving the lungs with fresh air. 



''2.1 he motion of the lungs in breathing does i\ot change 

 the colour of the blood in that part. 



" For Lower, on opening the pulmonary vein of a dog near 

 the left auricle of the heart, when his lungs were kept dis- 

 tended and without motion by a constant supply of fresh 

 air, observed the blood drawn to have the same florid co- 

 lour as the arterial blood of other parts. 



" Further, if the motion of the lungs changes the colour 

 of the blood from a dark purple to a bright red, I see no 

 reason why the motion of the muscles, when continued for 

 some time, should not keep up that red colour in the veins; 

 and constqucntlv, why, under strong exercise, venal blood, 

 contrary to experience, should not be of a bright red colour. 

 For a strong and vigorous motion of the nuiscles must un- 

 doubtedly contribute as much to preserve the bright red 

 colour of arterial blood, as the motion of the lungs contri- 

 tutes to produce it. 



" 3. The death of animals and extinction of flame in a 

 confined air are not caused bv a diminucion.of its elasticity. 



" For there is sometimos as great a diminution of elas- 

 ticity in the air in violent storms of wind, and hurricanes, 

 as there is in a small quantity of confined air at the time 

 when animals die, and candles go out in it, and yet no such 

 effects follow\ Further, if animals die and candles go out 

 in a confined air from a diminution of it-; elastieitv, then 

 these effect^ would not be produced in different quantities 

 of confined air until its elasticity w^as equally diminished in 

 them ; ))at it has been found by expernncnts, that at the 

 time when animals die and candles go out in two different 

 quantities of confined air, there is a greater dnT)lnution of 

 elasticity in the smaller quantity than in the greater : and 

 therefore life and flame are not destroyed by a diminution 

 of the elastieitv of the air. This is further confirmed from 

 , an experiment mentioned above ; for if effete air, however 

 forcibly blowi on live coals, extinguishes them in like man- 

 ner as it does VI hen in a state of rest, then tlie same effete 

 air, which in a quiescent state cannot preserve life, will not 



be 



