CHEMISTRY AND THE LAW OF CHANGE. 147 



increase its durability, in proportion to the size of the 

 scantlings ; and an unsound portion seems to have the 

 property of infecting the surrounding timbers with its 

 own decay. Thus the ravages of dry-rot spread rapidly 

 in every direction. 



The observer, in the course of a few hours' journey 

 through the forest, may thus witness the process of 

 conversion, as carried on in the great chemical labora- 

 tory of Nature, proceeding in every stage of its pro- 

 gress; and the practical chemist who has made these 

 matters his study would have no difficulty in demon- 

 strating that this is effected without one particle of 

 waste. 



Indeed it may be accepted as an axiom of chemical 

 science, that everything is unceasingly undergoing a 

 process of change, but that nothing is lost. It is true 

 that the apparent residuum is often small when compared 

 with the magnitude of the mass that is acted upon; 

 but that makes no difference in a scientific point of 

 view ; it is merely so, because many of the products 

 are given off in an impalpable form, such for instance 

 as gases of various kinds, which in their turn are 

 absorbed and assimilated by living organisms ; and they 

 thus become under different conditions integral por- 

 tions of living plants and animals. It would, however, 

 obviously be out of place to attempt any technical 

 description of the processes of decomposition and re- 

 construction in these pages: processes which, as we 

 know, are continually in operation throughout the whole 

 realm of created nature even the living plant and animal 

 is not exempt from this universal law of life. Physio- 

 logists for instance have even gone so far as to calculate 

 the approximate term of years which it takes to change 



