ElvISHA MiTCHEIvIy SCIENTIP^IC SOCIETY. 31 



the influence of the periodic law is deeply felt as any one 

 can see by examining- into their condition a dozen years 

 ago and comparing- it with the present. Still they are a 

 most unsatisfactory guide to the truths of the science. 

 Some have maintained that the periodic system was little 

 more than those same old groups or families. That shows 

 great ignorance, and a most superficial study of the peri- 

 odic system. It does include all that was of value in the 

 old groups but much more besides. 



The history of the atomic theory is repeated in that of 

 the periodic system. It is now meeting something of the 

 opposition and even denunciation which the atomic theory 

 met with in the third and fourth decades after its an- 

 nouncement. The unexplained exceptions to it are being 

 magnified and many are inclined to think them insupera- 

 ble and to look with doubt upon the entire system, while 

 some are ready to throw it overboard as rubbish past its 

 usefulness. 



I do not think that in these classes of opponents will be 

 found any who have made patient and thorough study of 

 this system. To me, the more I study it the more its in- 

 terest and value grows and the more fascinating the 

 search after the great truths which unquestionably lie 

 within it and of which it yields glimpses even in its incom- 

 plete state. For the system is incomplete. It cannot 

 well be otherwise until our knowledges of the science is 

 broader and deeper. It will grow with and direct the 

 growth. 



But in its incomplete state it is amply sufficient to act 

 as a most helpful guide to the study of inorganic chemis- 

 try. It introduces order and clearness where such were 

 previously, in large measure, lacking. It saves much 

 useless repetition and so brings about conciseness and 

 brevity, a saving that appeals to both teacher and pupil. 

 There are few earnest students who will not become en- 

 thused with the wonderful symmetry of the science and 

 hence of all nature when this Natural System is unfold- 



