June 10, 1898.] 



SCIENCE. 



789 



ness and humility which are so character- 

 istic of the master; and this now brings us 

 to the most important event of the day — the 

 formal address of Ostwald. 



The speaker did not think it desirable to 

 take up a special topic in physical chemistry, 

 because a number of those present were in 

 other fields, and would scarcely have fol- 

 lowed him. He, therefore, chose a more 

 general subject, which touches all branches 

 of science, and in which all must be inter- 

 ested — The problem of time. This problem 

 is discussed at first philosophically, and 

 then its direct bearing upon physical chem- 

 istry is pointed out. Newton regarded time 

 as objective, and distinguished in his Pri7i- 

 dpia between absolute and relative time, 

 regarding the latter as being contained in 

 the former. Kant took the opposite view, 

 that time as well as space is subjective. 

 But this idea did not exert its influence on 

 the natural sciences until about the middle 

 of this century. The experimental develop- 

 ment of the physiology of sensation brought 

 out the subjective nature of sense impres- 

 sions so clearly that the importance of 

 Kant's suggestion began to be felt. We 

 must not regard our conception of time as 

 complete, but recognize that it is affected by 

 the physiological conditions of our exist- 

 ence. I regard time as the most general nat- 

 ural law. ISTatural laws have this charac- 

 teristic: They allow the infinite variety of 

 possibility to be reduced to a special case, 

 or to special cases of reality, and their sig- 

 nificance is the greater the more numerous 

 and manifold the phenomena to which the 

 reduction finds application. In this sense 

 time is a natural law. The conception of 

 time expresses relations which are repeated 

 in very widelj^ different phenomena. 



Ostwald then proceeds to analyze our 

 conception of time, and finds in it the fol- 

 lowing four elements : 



First, continuity. Time moves on with- 

 out interruption. During sleep we cannot 



recognize time, and should be led to con- 

 clude that it had been interrupted. But 

 the consideration of the objective world, 

 which has progressed during our sleep,, 

 shows that the discontinuity of time is only- 

 apparent, and that it has really progressedl 

 without interruption. 



Second, the linear nature of time. Time 

 is a constant magnitude of such a nature 

 that it is possible to pass from one definite 

 value to another, only in one ivay. This is 

 the same as to designate time as having 

 one dimension. 



Third, time never returns to a point or 

 value which has been once passed, and is 

 thus to be distinguished from a line with 

 which it has much in common, since a line 

 can be easily so drawn that it will cut 

 itself. 



Fourth, time moves on in one definite 

 order. This is absolute, and a given suc- 

 cession in time cannot be reversed. 



After inquiring into the origin of our 

 conception of these four elements into 

 which time has been analyzed, the speaker 

 then considered the bearing of this discus- 

 sion upon physical chemistry. A very im- 

 portant chapter in physical chemistry is 

 that which deals with the velocity of reactions. 

 A solution of this problem would not only 

 complete a chapter of the science, but 

 would throw light upon the most funda- 

 mental questions of psychology, and conse- 

 quently of philosophy. 



The chemist Wenzel furnished the foun- 

 dation, more than a hundred years ago, 

 for the law which obtains for reaction ve- 

 locity — that under the same conditions, the 

 velocity is proportional to the concentra- 

 tion of the reacting substance. More care- 

 ful investigation showed that reaction ve- 

 locity depends upon the nature of the 

 reacting substances, their concentration 

 and temperature, and other conditions 

 which influence it, entirely out of propor- 

 tion to the apparent magnitude of the 



