go MR. BRANDE*3 VIENV OF TriB 



Carbonic acid, gafeous bodies pofTeflfed of acid properties. The effects of 

 w'^¥'^\' % carbonic acid are defcrlbed as follows by Pilatre de Rozier:— * 



delCnbed by Pi - •' 



Utrede Rozier. He went into a brewer's tub which was full of carbonic acid 



gas; he ni firft fek a flight heat throughout his whole body, 

 which produced a gentle perfpiration ; an itching fenfation 

 frequently obliged him to clofe his eyes, and on attempting to 

 breathe, he was prevented by a very violent fenTe of fuflfocationi 

 He wiftied to get out of the tub, but being unable to find 

 the ladder, the neceffity of breathing increafed, he was feized 

 with a violent gidditieft, and feJt a tingling fenfation in his 

 ears. He at length contrived to extricate himfelf, and al- 

 though he then experienced no difficulty in breathing, he wa^ 

 unable to diftinguifh the obje6ls around him ; his hearing vvas 

 alfo much impaired. On repeating the experiment he found, 

 Ihat as long as he remained without attempting to breathe, he 

 could readily move or even fpeak, but whenever he tried in** 

 fpiration, a violent fenfe of fuffocation came on. 

 Gafes which can But there are certain gafeous bodies which may be drawi* 

 be admitted n^^c> j^^^^ j^j^^ lungs, meeting with no oppofition from the organs of 

 refpiralion. Dr. Thomfon has divided tliefe into four clatTes. 

 The firft fet, he obferves, occalion immediate death, but pro- 

 duce no vifible change in. the blood ; they occafion the ani- 

 mal's death, merely by depriving him of air, in the fame 

 Hydrogen and planner as were he immerfed in water : the only gafes belong*. 

 azotkillby mere -j^^ jq jj^jg ^,]^^^ ^^e hidrogen and.azot. The fecond fet occa- 

 fion immediate death alfo, but at the fame time produce cer- 

 tain alterations in the blood ; and therefore kill, not only by- 

 depriving the animal of air, but by certain fpeci fie properties: 

 Gafes which kill the gafes belonging to this clafs are, carburetted hydrogen, 

 by a fpjedy pofi- fyiphuretted hydrogen, carbonic oxide, ajid perhaps alfo ni- 

 trous gas. The third fet of gafes may be breathed for fome 

 time without injury, but death enfues at lafl, provided their 

 Nitrous oxide a6ion be long enough continued:, to this clafs belong the ni- 

 and oxigen kill i^qus oxide and oxigen gas. The fourth fet may be breathed 

 ^y^^^ any length of time without injury : the only gafeous body be- 



Atmofpheric air longing to this clafs, is the air of the atmofphere, that com- 

 maintains life. pQ^^j^j ^f oxigen and azot every where furrounding the globe. 

 This compound - After an animal has breathed a certain quantity of a!rT for a 

 fluid lofesitsox- gj^^,^ time, it becomes totally unfit for refpiration ; and if the 

 , ^gfj air thus refpired be chemically examined, we fliall find that 



and carbonic acid the oxigen is greatly diminiflied, and that a confiderable quan- 

 gos is produced, j-j yf carbonic acid gas has been produced. 



It 



