THE CHEMISTRY OF TO-DAY. 595 



tuous to make any statement in regard to the way in which the 

 atoms are connected in the molecules. Yet this is just what the 

 chemist of to-day does, and the results accomplished by working 

 in the way referred to fully justify him. Let no one to whom the 

 facts are unknown accuse him of indulging in useless speculation. 

 Chemical hypotheses are for the use of chemists ; and so long as 

 they are helpful, so long as they lead to a clearer and clearer recog- 

 nition of the great truths of our subject, so long as they lead us 

 on to work, and the science grows in consequence, it is not perti- 

 nent to remark that there may possibly be a flaw somewhere. If 

 there are flaws in chemical hypotheses, they will be recognized by 

 chemists themselves sooner than by others. Let no one think 

 that science has nothing to do with the realm beyond the senses. 

 Without the aid of the imagination there could be no science. 

 However important they are, facts alone could not constitute a 

 science. It is necessary that the relations between these facts 

 should be discerned, and this can not be done except by the aid of 

 the imagination, Tliere have been few bolder flights than those 

 which pertain to matters of science. The greatest genius is he 

 who sees furthest beyond the facts, and with the aid of his imagi- 

 nation is able to bring together into a harmonious whole those 

 facts which seem least connected. But, it must be remembered, it 

 is the imagination of the thoroughly trained mind, kept in sub- 

 jection by profound knowledge, that leads to great results. 



I have said that of late attempts have been made to learn some- 

 thing of the shape of molecules. Within a few months a remark- 

 able paper, written by Prof. Wislicenus, of the University of 

 Leipsic, has appeared, in which the actual arrangement of atoms 

 in the molecules is seriously and brilliantly discussed. I can not 

 even touch upon the contents of that paper. Suffice it to say that 

 chemists generally are profoundly interested in the arguments of 

 Wislicenus, and the subject is now under active discussion. To 

 me it appears that the views put forward are well worthy of most 

 serious consideration. What the outcome will be, none can pre- 

 dict ; but, at all events, the fact is significant that chemistry has 

 reached a stage when such a subject can be discussed. 



Another subject which is coming to the front in chemistry is 

 that which I had in mind at the beginning of this article when I 

 said, " I accejjt this statement as expressing half the truth," It 

 is unquestionably the chemist's business to tell what things are 

 made of, but the other half of the truth is this : it is also his busi- 

 ness to study the chemical act itself. In any given case he must 

 not be satisfied when he has learned that when two substances, 

 A and B, are brought together, they combine to form the new 

 substance, A B, He must study that act of combination, and 

 learn all he can about it. As these acts in most cases take place 



