rOL. v.] PHILOSOPHICAL TRANSACTIONS. 4g5 



orifice; that the wood being covered with a close and yielding cement, for pitch 

 or the like common stuff will not always serve the turn, we might be able to tie 

 the bladder fast and close enough upon the thus fitted stopple. 



And now to reduce these things to practice, and by their help make our de- 

 signed experiment, we included a mouse into a receiver made according to this 

 way, leaving in the bladder as much air as we thought might suffice him for as 

 long a time as the experiment was to last. Then putting this limber or exten- 

 sible receiver, if I may so call it, into an ordinary one of glass, and placing this 

 engine near a window, that we may see through both of them ; the air was by 

 degrees pumped out of the external receiver, (as for distinction sake I shall call 

 it,) and thereupon the air included in the bladder did proportionably expand it- 

 self and so distend the internal receiver, till being arrived at a degree of rare- 

 faction, which rendered it unfit for the included mouse's respiration, I perceived, 

 though with some difficulty, in this animal the signs of his being in great 

 danger of sudden death. Whereupon the outward air, being hastily let into 

 the external receiver, compressed the swelled bladder to its former dimensions, 

 and thereby the included air to its former density, by which means the fainting 

 mouse was quickly revived. Having given him some convenient time of respite, 

 the experiment was repeated with the like success, and we doubted not but the 

 third trial we made would have ended as the two former did; but that, whilst 

 we were considering of the sickness of the mouse, which, by reason of some 

 opacity that could scarcely be avoided in the wrinkled bladder, was not as to its 

 degree so easily taken notice of, it became irrecoverable by the subsequent 

 condensation of the air. 



N. B. The confirmation of this by further experiments will properly fall under 

 another title. 



The Thirteenth Title. 



Of an unsuccessful Attempt to prevent the Necessity of Respiration hy the Pro- 

 duction or Growth of Animals in our Vacuum. 



Having had frequent occasions to observe how quickly those animals, whose 

 blood is actually warm, did expire in our vacuum; and that even those animals 

 with lungs, whose blood was actually cold, were not able to live any considerable 

 time there; I thought it worth while, though extremely difficult to try, whether 

 there might not be some ways yet unpractised, either to make such animals as 

 nature endows with lungs, live without respiration, or at least to bring such in- 

 sects, and other animals, as can already live without air, to move also without 

 it in our vacuum. 



