MARSH AIR. 427 



5. Sulphurated and phofphorated hydrogen gafes. If 

 thefe elaflic fluids confift of hydrogen gas, holding fulphur 

 and phofphorus In folution, it feems probable that they 

 lliould be generated during the putrefadlion offuch matters 

 as contain them as conftituent elements. Although Chap- 

 tal in his Memoirs de Chimie, p. 141, obferves : " Que la 

 boue noire, degagee dc tout vegetal, ne donnoit plus d'air 

 inflammable mais repandoit unc odeur de foie de foufre." 

 Still he relates no experiment whereby he detedled its pre- 

 fence in the atmofphere of marfhes. Its ready abforption 

 by water ; marfli air when agitated with a folution of the 

 acetite of lead producing no change in it ; filver not tarnifh- 

 ing fooner in thefe than in other moill fituations ; and the 

 air poflefljng no peculiar Imcll, are all faifts which tend to 

 convince me that it does not oiift ; moreover, Kirwan fays, 

 that hepatic gas united with nitrous air will depofit fulphur. 

 I agitated marfh air and nitrous air together in a glafs tube 

 and no fuch phenomenon v/as noticed. 



6. Azotic gas. If you burn candies in the air of marflr- 

 es, until all the oxygen be abforbed, and then agitate the 

 remaining air with lime water fo as to abforb the carbonic 

 acid, an elaflic fluid fl.ill remains which poflTefies the pro- 

 perties of azotic gas. 



yth and laftly. Oxygen gas. A variety of fadls prove 

 that oxygen gas is a principal ingredient in the atmofphere 

 of marfhes ; ifl:, candles burn therein with the fame luftre 

 as in other fituations. 2. Animals breathe with equal eaie 

 as in other places. 3. Eudiometrical experiments prove 

 that it forms as great a proportion here as in other atmof- 

 pheres which are reckoned more healthy. 



Auguft 4th and 5th, 1796 — July 8th and loth, 1798 — 

 I colleded air from over marfliy grounds to the fouth and 

 north of Philadelphia ; when tried with the Eudiometer, 

 they always proved as pure as the air in the yard ot my 

 lodgings. Chaptal in his Memoirs de Chimie, p. 141. 

 3 K 2 aflTerts 



