236 ON THEMICAL ENERGV. 



What lias liere been stated for a few cases is a general truth. In 

 every case where different substances which could act upon one another 

 are in contact without having, practically speaking, any apparent 

 action upon each other, we can bring the requirements of the teachings 

 of energy into unison with the actual conditions by actually ascribing 

 to these substances an action which is, however, s<» slow that it lies 

 beyond the possibilities of nieasurenient. 



We have here the means of entering upon one of tiie most important 

 and mysterious problems, namely, the search after the chemical activ 

 ity of organized bodies, for, as all the activity of organisms depends 

 upon changes in their chemical energy, all knowledge in this case 

 depends upon a correct elucidation of the character of the chemical 

 changes. If we can understand how the chemical processes of com- 

 bustion, to which all physiological sources of energy finally lead, can 

 be so regulated that they are able at any moment to adapt themselves 

 to the ever-changing requirements of the organism, we have taken a 

 steji in every respect most important in the knowledge of life. 



Let us take, for instance, a mixture of oxygen and hydrogen. Under 

 ordinary circumstances we can preserve this mixture for a long time 

 without the formation of a measurable ainount of water. If however 

 we place a piece of platinum sponge into it the formation of water 

 immediately begins, and it is as suddenly terminated when we remove 

 the sponge. The i^latinum sponge has moreover undergone no change 

 and is able to exert this action for an unbounded space of time. 



At first it seems as if we had here the first iirojiosition of our later 

 natural science, to rudely dispute '' causa arguat effectum,'''' since we 

 have here a cause whicli can bring forth extended and large effects at 

 pleasure without becoming exhausted. If we ask however Avhat this 

 proposition means by cause and effect we find it to be degrees of energy. 

 No energy of any kind can be created without the consumption of an 

 equal amount of energy, and no difference in tlie potential of energies 

 can be called forth without the simultaneous disappearance of equiva- 

 lent differences in the potential of other energies. The truth of these 

 propositions is not cast in doubt by the experiment with the mixture 

 of oxygen and hydrogen, since the heat of combustion remains the 

 same both when combination is effected by an electric spark and when 

 it is brought about at the ordiiuiry temperature by means of platinum 

 sponge. While therefore the law of cause, clothed in the form of a 

 principle of energy, regulates the final result of the action in an 

 unchangeable manner, the time during which this action takes place 

 remains absolutely iiub'pendent of this principle, and we have side by 

 side with the absolute necessity of this law of cause, the freedom with 

 reference to the time during which it exerts its infiuence. Therefore 

 we see that all possible phenomena which, (u^iginating from tlie same 

 substances, reach the same jjroducts, arrive at tliese with a very dif- 

 ferent rapidity. The object to be arrived at is uncliangeablc; whether 



