MAGNITUDE AND MINUTENESS. 



reproduced, as well as tfie constituents of the fuel itself, the latter 

 of which being weighed, as well as the incombustible ash, the 

 weight of the whole is found to be precisely equal to the weight of 

 the fuel which was burned and apparently destroyed. 



38. Liquids when subjected to heat are converted into vapor, 

 and this vapor disperses in the atmosphere, so that the liquid 

 seems to be boiled away ; but if the vapor be preserved, as it may 

 be in a separate vessel, and exposed to cold, it will return to the 

 liquid form, and its weight and measure will be found to be pre- 

 cisely the same as that of the liquid evaporated. 



39. There is a process in chemistry which is called destructive 

 distillation. The term is objectionable, because it implies a de- 

 struction where no destruction takes place. If a piece of wood, 

 being previously weighed, be placed in a close retort and submitted 

 to what is called destructive distillation, it will be found that 

 water, a certain acid, and several gases will issue from it, all of 

 which may be preserved, and mere charcoal will remain in the 

 retort at the end of the process. If the water, acid, and gases 

 which thus escape be weighed with the charcoal, the weight of the 

 whole will be found to be precisely equal to that of the wood which 

 was subjected to destructive distillation. 



40. Thus various forms of matter may be fused, evaporated, or 

 submitted to combustion ; animals and vegetables may die, orga- 

 nised bodies may be dissolved and decomposed, but in all cases 

 their elementary and constituent parts maintain their existence. 

 The remains of our own bodies after death are deposited in the 

 grave, and enter into innumerable combinations with the mate- 

 rials of the soil, with the vegetation which covers it, and the air 

 which circulates above it. 



Consequently, these parts enter into an infinite series of other 

 combinations, forming parts of other organised bodies, animal and 

 vegetable, and which, after having discharged their functions, 

 are thrown off again, mixing with the soil, the air, or organised 

 matter, and once more running through the round of physical 

 combinations. 



The constituent atoms of matter are thus constantly performing 

 a circle of duties in the economy of nature with infinitely more 

 certainty and regularity than is observed in the most disciplined 

 army or in the best regulated manufactory. 



203 



