530 PHILOSOPHICAL TRANSACTIONS. [aNNO 1779. 



of determining the degree of tiie salubrity of the air by means of nitrous and 

 inflammable air. 



Having introduced 8 cubic inches of common air into the same bladder, I 

 breathed it as long as I could ; beginning after a natural expiration as in the ex- 

 periment above related. I breathed it 34 times successively, and afterwards 

 found it very much altered, so that it extinguished a light many times successively. 

 An animal introduced into a vessel of that air immediately gave signs of uneasi- 

 ness; and the air being tried with the nitrous air gave II -f- 20, III -j- 15; 

 whereas, before it had been breathed, it gave with the same nitrous air II — 15, 

 II + 18. 



This experiment shows, that the air which remained in the bladder in the first 

 experiment, was not so good as that breathed 34 times successively. In order to 

 make this experiment with more precision, I breathed in 80 cubic inches of 

 common air, introduced into the same bladder, only 1 1 times ; beginning after 

 a natural expiration. I then examined this air with the nitrous air, and found 

 that it gave II — 13, III -f 28. Hence it is plain, that the mixture of inflam- 

 mable and pulmonary air, breathed 1 1 times, is much inferior to common air 

 breathed an equal number of times ; so that there can remain no doubt but that 

 inflammable air is at least worse than common air. 



Willing, however, to ascertain this matter still better, I tried to breathe it 

 immediately through a large receiver, partly immersed in water, and swimming 

 in it, so that the air within the receiver was of the same elasticity with the ex- 

 ternal air. For this experiment I made use also of a glass tube bended in 2 dif- 

 ferent directions. The air contained in the receiver was about 250 cubic inches. 

 In all the trials made in this manner, I was never able to breathe the inflamma- 

 ble air more than 3 times, and even at the 2d inspiration I felt a great oppres- 

 sion. As these experiments can be depended on, because they were often and at 

 different times repeated, there seems to be reason enough to suspect, that the 

 bladder might possibly alter the nature of inflammable air, and render it more 

 fit for respiration, notwithstanding that the mere contact of the bladder seemed 

 not sufficient to produce such an effect, which is irreconcileable with other 

 facts : yet some reason must certainly exist sufficient to explain Mr. Scheel's ex- 

 periments, which directly prove that the inflammable air contained in bladders 

 can be breathed with impunity. 



When I breathed this air according to Mr. Scheel's manner 1 1 times succes- 

 sively, I not only breathed it without any inconvenience, but observed that the 

 first inspirations were even pleasing ; more so than when I breathed common air. 

 I felt a facility of dilating the breast, as if the air was as light as that at the top 

 of high mountains. I never felt a like sensation, even when I have breathed the 

 purest dephlogisticated air. I do not think that I was mistaken in these sensa- 



