Chap. 6.] Putrefaftion. 71 



putrefaction are the fame as thofe which promote the 

 fpirituous and acetous fermentations, viz. humidity, the 

 admiffion of air, and a due degree of heat. Heat to 

 a certain degree promotes putrefaction, yet 20 above 

 that of the human blood feems to prevent it. A fmall 

 piece of fifh which was luminous, and confcquently 

 putrid, was put into a thin glafs ball, and water of the 

 heat of 1 1 extinguifhed its light, and confequently 

 flopped its tendency to putrefa6tion, in lefs than half a 

 minute ; on taking it out of the water, it began to re- 

 cover its light in about ten feconds, but was never fo 

 bright as before *. 



Azote, which abounds fo much in animal fub- 

 ftances, not only occafions a more rapid putrefaction, 

 but renders its products confiderably different from 

 thofe afforded by the decay of fuch vegetables as do 

 not contain azote. In the putrefaction of animal 

 matters, the hydrogen, inflead of efcaping in a feparate 

 date, combines with the azote, and forms volatile al- 

 kali. The hydrogen gas alfo difTolves a part of the 

 carbon, the fulphur, and the phofphorus, all which 

 ilibflances enter into the compofuion of animal 

 matter; with thefe, it forms compound aeriform 

 fluids, which have obtained the following names, car- 

 bonated hydrogen gas, fulphurated hydrogen gas, and 

 phofphorated hydrogen gas. The two latter of thefe 

 gaffes have a peculiar, difagreeable odour, and.> together 

 with the volatile alkali, occafion the penetrating and' 

 o^ffenfive exhalations which proceed from putrid mat- 

 ters. Sometimes volatile alkali predominates j which 

 affects the eyes; fometimes, as iri feculent matters, the 

 fulphurated gas is moft prevalent; and fometimes, as 

 in putrid herrings, the phofphorated 'hydrogen gas is 



* Prieflley's Hift. of Optics, p. 579. 



F 4 moft 



