38 CHEMISTRY AND PHYSICS IN RELATION 



SECONDLY : BY AN ATTRACTIVE OE REPULSIVE FORCE, 



2. By the action of an attractive or repulsive force, which is interposed between 

 two bodies. In this the action is always mutual, and the speed obtained inversely 

 proportionate to the masses moved. 



CHEMICAL PROCESSES, AS PHENOMENA OF MOTION, BELONG TO 

 THE SECOND KIND, 



As one must consider chemical processes as phenomena of motion, it is not to 

 he doubted that all such processes as can be explained by the formation of new 

 compounds belong to the second class of phenomena of motion, while the attractive 

 f re f th constituents, or their chemical affinity, calls forth the change of place 

 :-nd prop rty (that is the motion) of matter. After the establishment of the corn- 

 bin tio , motion ceases, as when the falling stone has reached the ground, and the 

 ir n filings the pole of the magnet. 



PUTREFACTION AND FERMENTATION BELONG TO THE FIRST ORDER 

 OF PHENOMENA OF MOTION. 



But when a body which is undergoing decomposition, that is, whose parts are 

 in a state of change of place and of motion, converts another body into a similar 

 condition ; and if observation have shown that all other known causes, excepting 

 one alone, must be excluded from any participation in the change, or decomposition 

 of the second body ; and if it be proved that this one cause (cpmmunication of 

 motion, friction, a blow, <fec.), have a decided share in the formation and decom- 

 position of a number of combinations, this one cause must be regarded as the 

 final acting one, especially, if the views gained in the theory of motion, be appli- 

 cable to chemical actions. The recognition of this last, and only cause, is there- 

 fore not a mere word that has been substituted for the term " catalytic force;" but 

 Ithe expression of an idea, which is strictly the opposite to that of a catalytic body. 

 Prom the facts advanced in (2) p. 84, the erroneous conclusion is drawn that gravi- 

 tation, magnetism, <fec., are examples of the motion of one body through another 

 at rest. 



THE FORCE OF GRAVITATION GIVES NO RISE IN ITSELF TO MOTION. 



A clock is kept in motion by the. weight, but cannot draw it up by itself, and the 

 heat of the sun has as little share as gravitation in the action of a mill-wheel. The 

 water which impels the mill-wheel was previously vapour the vapour was fluid 

 water. 



The water underwent evaporation ; the vapour, on the abstraction of heat, be- 

 came again aqueous, and this liquid water falls by the action of gravitation, and 

 continues to fall until, as in the clock, resistance arrests its motion. 



WANT OF CORRECTNESS IN EXPRESSION, THE CAUSE OF ERRONEOUS 

 CONCLUSIONS AND MISUNDERSTANDINGS. 



Besides the erroneous conclusions and methods of investigation which are com- 

 prised in this one clause, there is yet one individual fault to be added, which pre- 

 vails amongst many physiologists, and which can be explained only on the plea of 

 carelessness. This failing is, to regard things or phenomena, that have been per- 

 ceived by the senses, as representing conclusions of the mind, which brings along 

 with it this great disadvantage, that in order to esteem a fact as true, these natural- 

 ists require to have ocular demonstration of known causes which cannot be per- 

 ceived by the senses. 



From this it may arise that chemists, in spite of a superabundance of the most 

 evident facts, are frequently unable to convince physicians of the simplest truths. 



