MARSH AIR. 421 



with a very fmall portion of atmofpheric air, were at dif- 

 ferent times confined in bottles clofely {topped and invert- 

 ed over water : in fome inftances the experiment was con- 

 tinued during 20 and 30 days. They were fubjeded to 

 the temperature of the atmofphere. During the progrefs 

 of the experiments, I perceived that an elallic fluid was 

 difengaged from the materials contained in the bottles, and 

 that the water was evidently diminifhed in bulk ; the elaftic 

 fluid generated during thefe experiments, ilf, inltantly 

 formed a copious white precipitate when agitated with lime 

 water ; idly, it burned, when the flame of a candle was 

 applied to it, and pofTefTed the other properties, which are 

 common to air obtained by agitating ftagnant waters over 

 marfhes. 



Thefe fails are decifive to me on the fiibjed, and con- 

 firm the above conjedures refpeding the origin of the hy- 

 drogen gas difengaged rrom marfhy grounds. It is necef- 

 fary to remark, that fome danger attends thefe laft experi- 

 ments ; for a large bottle which was clofed by a ground ftop- 

 per, was broken on the 25th day of the experiment, by 

 an expanfion of the contained elaftic fluid : the pieces, 

 which were large, were thrown to the diftance of 20 feet, 

 and a report was heard louder than that from the firing of a 

 muflcet. In general, the bottles had corks faftened by 

 means of firings bound round them : as loon as I cut the 

 firings, the corks were forced from the necks of the bot- 

 tles with confiderable violence. 



The above experiments teach us that mud vitiates the at- 

 mofphere in a very powerful manner. They alfo enable 

 us to account for the prefence of the elaftic fluid forming 

 the atmofphere of marfiies. It appears, that, the carbone 

 of the mud unites with the oxygen of the decompoled wa- 

 ter, and forms the carbonic acid gas, whilft the hydrogen 

 gas is fet at liberty. Thefe are truths not to be invalidated 

 by gratuitous aflertions, fince their bafis is experiment. 



It 



