MARSH AIR. 417 



I ani not without hopes that others will engage in the 

 inquiry, it is of importance to every citizen, more efpeci- 

 ally fince we find that our principal cities are almoft year- 

 ly afflided with a terrible epidemic, which has been by 

 fome attributed to the ftatc of the air. Future difcoveries 

 it is hoped will multiply the number of tefts for airs, and 

 thus render the fubjed: more eafy. 



Refpedable chemifts have determined the component 

 parts of our common atmcfphereto be 

 Oxygen gas 27. 

 Azotic gas 72. 

 Carbonic acid gas 01. 



Any deviation from this ftatement mufl be attributed to 

 local circumftances. 



1 fhall firft endeavour to determine, whether or not the 

 air of marflies differs from that of other fituations : 



2. What are the caufes of the differences which are found 

 to exift : and 



3. Make a few obfervations and remarks. 



I. March 31ft, 1798. Air was obtained by agitating 

 ftagnant water over marfliy grounds ; the following ex- 

 periments were then performed. 



a. It burned when a candle was applied to it ; the flame 

 was blue : it did not explode when mixed with atmof- 

 pheric air. 



b. Agitated with lime water, a copious white precipi- 

 tate was formed. 



c. Its bulk was confiderably diminiflied by agitating it 

 with lime water. 



d. Equal bulks of it and nitrous gas were introduced in- 

 to my eudiometer tube, and a diminution of -4t3- of their 

 bulk was perceptible. 



Thefe experiments were frequently repeated and the re- 

 fults were fimilar to the above-mentioned : they warrant the 

 following inferences: 



3 I a. That 



