274 EREMACAUSIS OR DECAY 



gion ; for the communication of the state of com- 

 bustion is in reality the effect of the contact. 



It is decaying wood which causes fresh wood 

 around it to assume the same condition, and it is 

 the very finely divided woody fibre in the act of 

 decay, which in moistened gall-nuts converts the 

 tannic acid with such rapidity into gallic acid. 



A most remarkable and decided example of this 

 induction of combustion has been observed by De 

 Samsure. It has already been mentioned, that 

 moist woody fibre, cotton, silk, or vegetable mould, 

 in the act of fermentation or putrefaction, converts 

 oxygen gas which may surround it into carbonic 

 acid, without change of volume. Now, De Sam- 

 sure added a certain quantity of hydrogen gas to 

 the oxygen, and observed a diminution in volume 

 immediately after the addition. A part of the 

 hydrogen gas had disappeared, and along with it a 

 portion of the oxygen, but a corresponding quantity 

 of carbonic acid gas had not been formed. The 

 hydrogen and oxygen had disappeared in exactly 

 the same proportion as that in which they combine 

 to form water ; a true combustion of the hydrogen, 

 therefore, had been induced by mere contact with 

 matter in the state of eremacausis. The action of the 

 decaying substance here produced results exactly 

 similar to those effected by spongy platinum ; but 

 that they proceeded from a different cause was shown 

 by the fact,that the presence of carbonic oxide,which 



