ELISHA MITCHELL SCIENTIFIC SOCIETY. 77 



perfections of the law's orig-inal form or rather the table 

 as first brought out. Probably some have ventured to 

 comment upon it. Such criticisms have escaped me with 

 one or two exceptions. 



It is with much hesitation that I venture to point out 

 what seem to me to be imperfections and blemishes in 

 so great a work. Few may agree with me in calling 

 them imperfections. I do not purpose to detract one 

 particle from the greatness and importance of the es- 

 sential truths contained in this discovery. Mendelej- 

 eff 's table, as we have it at present, is a great advance 

 upon the first one published by him in 1869 which must 

 be pronounced tentative only and decidedly unsatisfac- 

 tory. The table of Victor Meyer is far behind it in 

 presenting the facts of the periodic law. There 

 have been many attemps at devising a graphic repre- 

 sentation of this law. I know of none which can be 

 called real aids to the student or which do not intro- 

 duce new ideas which, to sa}^ the least, have no basis 

 in the facts as known to us at present. None of them 

 can be regarded as a safe substitute for the simple ta- 

 ble of MendelejefF. 



Taking that table I would venture to point out some 

 obstacles to its present full acceptance. These have 

 been in part revealed to me by the effort at an honest 

 presentation of this great truth of nature to honest- 

 minded, clear-sighted young men. Before mentioning 

 these difficulties which lie here in the path of a teacher, 

 I must preface that my criticisms are aimed at what I 

 may be allowed to call the tmessentials of the law. 

 Mendelejeff's great feat was in seeing clearly and an- 

 nouncing intelligently that the properties of the ele- 

 ments were dependent upon and determined by the at- 

 omic weights. This is the essential of the periodic 



