344 POISONS, CONTAGIONS^ MIASMS. 



in motion by any power can impart its onm motion 

 to another molecule with which it may be in contact." 



This is a law of dynamics, the operation of which 

 is manifest in all cases, in which the resistance 

 (force, affinity, or cohesion) opposed to the motion 

 is not sufficient to overcome it. 



We have seen that ferment or yeast is a body in 

 the state of decomposition, the atoms of which, 

 consequently, are in a state of motion or transposi- 

 tion. Yeast placed in contact with sugar, com- 

 municates to the elements of that compound the 

 same state, in consequence of which, the consti- 

 tuents of the sugar arrange themselves into new and 

 simpler forms, namely, into alcohol and carbonic 

 acid. In these new compounds the elements are 

 united together by stronger affinities than they 

 were in the sugar, and therefore under the con- 

 ditions in which they were produced further de- 

 composition is arrested. 



We know, also, that the elements of sugar assume 

 totally different arrangements, when the substances 

 which excite their transposition are in a different 

 state of decomposition from the yeast just men- 

 tioned. Thus, when sugar is acted on by rennet or 

 putrefying vegetable juices, it is not converted into 

 alcohol and carbonic acid, but into lactic acid, 

 mannite, and gum. 



Again, it has been shown, that yeast added to a 

 solution of pure sugar gradually disappears, but that 

 when added to vegetable juices which contain gluten 



