244 MA.NURES. 



tion of the atmosphere, since we have established that by this action 

 the woody fibre suffers loss in the elements of water besides what it 

 loses in carbon. This is confirmed by the following analyses. The 

 first, made upon some oak wood, previously purified by washing in 

 water and in alcohol, we owe to Messrs. Thenard and Gay-Lussac; 

 the succeeding one to Messrs. Meyer and Will : 



Oak wood. Id. rotten. Id. rotten. 



Carbon 52-5 ."ia.G 5H.2 



Hydrogen and oxygen, water -17.. 5 46-4 43-8 



TOOTO 100.0 100.0 



Wood decomposed under water, without being in direct contact 

 with the air, undergoes a different modification ; it is blanched in- 

 stead of blackened, and the carbon far from increasing is diminished. 

 Saussure thinks that this kind of alteration depends mainly on the 

 loss of the soluble and colorinir principles of the wood, principles 

 containing more carbon than the ligneous matter itself: so that pure 

 woody fibre exposed wet to the action of the air would yield pro- 

 ducts analogous to those which result from its decomposition under 

 water. 



The damp linen rags which are fermented in paper manufactories 

 afford a j)roduct which is white, and but slightly coherent. The 

 mass, which heats successively during the operation, loses about 20 

 per cent, of its original weight. This is exactly what takes place 

 in wood decayed by the alternate action of water and air, namely, it 

 becomes white and extremely friable. 



Some oak arrived at this stage of decomposition contained, ac- 

 cording to Liebig : 



Carbon 47-6 



Hydrogen 6-2 



Oxygen 44.9 



Ashes 1.3 



100.0 



Compared with the composition of oak wood when sound, these 

 numbers show that during its modification the wood has lost carbon, 

 and that ii has gained hydrogen. The elements of water must ne- 

 cessarily have intervened, and become fixed during the reaction. 

 Tjigneou.s fibre decayino under water is not thereby completely pro- 

 tected from the atmosphere. Water always holds some air in solu- 

 tion, and the oxygen of that air reacts exactly as if it were in the 

 gaseous state. 



Upon all the phenomena of dei^omposition connected with fermen- 

 fation, with j)Uirefaction, or with dilatory combustion, heat exerts 

 an influence which has certainly not been sufficiently appreciated. 

 Organic bodies sunk in a large mass of water are not exposed to 

 changes of temperature so various and abrupt as when they are 

 placed in the atmosphere; their decomposition is more gradual, 

 more uniform, and the s(»luble materials which they contain, or which 

 are the result of the alteration they are undergoing, are in a great 

 measure dissolved. Temperature may al.so produce great differencet 



