PROGRESS IN NINETEENTH CENTURY 237 



us now, regardless of its ultimate or physical nature, which may be 

 exceedingly complex. The conception is so bound up with all modern 

 chemical ideas that we cannot abandon it if we would, so long as 

 nothing better is offered us in its place. 



The chemist, then, may legitimately claim that matter, as we know 

 it, is made up of small, distinct particles, which, so far as they have 

 been chemically defined, are of few kinds. These particles gather 

 into clusters, through some form of attraction whose nature is still 

 unknown, and in which differences of position probably represent 

 differences of chemical structure. Allotropy and isomerism are thus 

 explainable, two phenomena that are perhaps the same, and for 

 which the atomic theory alone has offered any reasonable interpret- 

 ation. But this is not all. Certain numerical constants, commonly 

 known as the atomic weights, have been discovered, one for each 

 element, which are fundamental for all quantitative chemistry and 

 for an important part of physics. These constants are real ; they repre- 

 sent definite, measurable relations; and in one form or another they 

 will remain in use, apart from all changes in theory. Whether they 

 are independent of one another is yet to be determined; there are 

 indications that they may be connected by some mathematical law; 

 and should such an expression, a quantitative periodicity, be dis- 

 covered, it would go far towards enlightening us as to the real nature 

 of the elements themselves. The exact determination of the atomic 

 weights is therefore a matter of supreme importance and one bearing 

 directly upon the profounder problems of chemistry. If the atoms 

 are separable into electrons, the masses of the latter should bear some 

 relation to the atomic weights and give us clues to their mathematical 

 interpretation. Future investigations along this line are certain to 

 be made, and we may fairly hope that they will prove successful. 



The nineteenth century is often called the age of steam, and its 

 latter half the age of electricity. May we not, with equal propriety, 

 name it the age of chemistry? During the passage of its years chem- 

 istry has developed from an art into a science, with a clear philo- 

 sophy of its own, and with useful applications which affect all other 

 sciences and many industries. A great university may now employ 

 twenty chemists as teachers where fifty years ago there was barely 

 work for one. Training in chemical research has become a recognized 

 feature in higher education; the student is taught to think and 

 investigate; the production of new knowledge is seen to be a distinct 

 function of the teacher. Scholarship is now rated according to its 

 fertility ; and the man who merely knows, no matter how thoroughly, 

 the work of his forerunners, is given a low rank in the thinking world. 

 In the industries, chemical thought is translated into action, and so 

 becomes doubly creative, yielding at the same time new knowledge 

 and material wealth. Governments maintain public laboratories; it 



