VOL, LXIX.] PHILOSOPHICAL TRANSACTIONS. 529 



flammable air through the mouth only, without immerging their whole bodies 

 into it. I chiefly used bladders tied to their moutlis, but sometimes I also made 

 use of tubes which entered immediately into the wind-pipe. In both cases the 

 animals died in a very short time : hence it became evident, not only that the in- 

 flammable air is pernicious to animal life, but that it does not act on the body of 

 an animal ; for I kept some of them immerged in inflammable air, with the 

 mouth only out of it, and did not perceive any effect hurtful to them. 



It being thus ascertained that the inflammable air could not be breathed by 

 animals with impunity, it still remained to find out the cause of Mr. Scheel's mis- 

 take. I began therefore to breathe the inflammable air contained in bladders, after 

 the manner of Mr. Scheel. The inflammable air used in my experiments was 

 extracted from zinc and from iron by the action of the vitriolic acid, and it was 

 received into bladders that were dry in the inside, but a little moist on the out- 

 side. The quantity of air contained in each bladder was about 80 cubic inches. 

 The air coming out of the matrass passed through about one inch of water be- 

 fore it went into the bladders. At first I breathed the inflammable air witli a 

 kind of fear ; but finding that it occasioned no painful impression, I continued 

 breathing it with courage as long as I could. I breathed in a bladder filled with 

 it eleven times, beginning after a natural expiration. This air when taken out 

 of the bladder, was still inflammable, and being tried with the test of nitrous 

 air it gave II — 28, III + 20. 



Before going further I must explain the formula which I use to express the 

 diminution of respirable air, or air of other kind, when mixed with nitrous air. 

 My method is as follows : I have a glass tube of about 18 inches in length, and 

 half an inch in diameter, closed at one end, and of a constant diameter through- 

 out its whole length : tliis tube has a mark at every 3 inches, which marks or 

 divisions I call measures, and every inch is divided into 20 equal parts ; so that 

 every measure is divided into 6o portions, which I call parts. Into this tube, by 

 means of an instrument which measures always one constant quantity of air 

 equal to one measure of the tube, I introduce 2 measures of respirable air and 

 one measure of nitrous air, after which I measure the diminution ; then I intro- 

 duce a 2d measure of nitrous air, and again measure the diminution. The 

 whole measures I express in Roman characters, and the parts of a measure I ex- 

 press in common numbers; for instance, when I say II — l6 and II -f- 10, the 

 first expression means, that after having introduced into the tube 2 measures of 

 common air, and 1 measure of nitrous air, the space occupied by the mixture of 

 these two airs was 2 measures — l6 parts, or 6oths of a measure : and the 2d 

 expression shows that, after having introduced another measure of nitrous air, 

 the space occupied was 2 measures -f 10 parts. Tlie reason and particulars of 

 this method will be given liereafter, in a paper expressly written on the method 



VOL. XIV. 3 Y 



