4iB fiXPERlMENTSoN 



a. That carbonic acid gas enters largely into the compo- 

 fition of the air examined. 



b. That hydrogen gas is an ingredient in it. 



c. That no oxygen gas was prefent : for the fmall ab- 

 forption which took place, I attribute to the aftion of the 

 water with which the airs were agitated. 



The above experiments were performed on the air, which 

 was obtained immediately as it was difengnged from the 

 marfliy foil ; it became neceflary to examine the air lituat- 

 ed at fome diftance above the marrti. 



At different times during the fummer of 1798, I colledl- 

 cd air from above marfliy grounds : the following experi- 

 ment^ were performed on it. 



d. When agitated with lime water, it afforded a precipi- 

 tate, which was not fo abundant as in the former expe- 

 riments. 



h. Mixed with nitrous air, its bulk was diminiflied to 

 nlmolT: as great a degree as the air in the yard of. my lodg- 



c. Either pure or mixed with atmofpherlc air, it did not 

 burner explode when a candle was applied to it. 



Hence it appears that the air obtained at the height of 

 feveral feet above marfhes, 



1. Contains little or no hydrogen gas. 



2. That the proportion of carbonic acid gas is pretty con- 

 fiderable ; and 



3. What is of great confequence to be obferved, a large 

 quantity of oxygen gas enters into its compofition. 



The laft mentioned fadls induce us to believe that the air 

 above marfhcs is not confiderably different in its properties 

 from the common atmofphere in other fituations, where 

 animals refpire with eafe and enjoy perfetEl health, except 

 the proportion of carbonic acid gas being greater ; and this 

 I am induced to believe diminilhes in quantity as we afcend: 

 for fa(^s related by travellers who have vifited the Grotto 



del 



