508 



SCIENCE. 



[N. S. Vol. II. No. 42. 



much dogmatism to young students half- 

 discovered truths. 



5. The system gives us certain tj'pical 

 elements. From these can be deduced the 

 properties for the various members of the 

 groups, and their treatment is greatly sim- 

 plified. The old division into families, 

 which was partial only, is broadened and 

 filled out in the new groups. 



6. I freely acknowledge that there are 

 difiSculties to be met. How could we ex- 

 pect it to be all plain sailing where our 



I offer this only as possessing the value 

 of success under personal trial. 



I do not propose it as something free from 

 objections, but merelj^ as the best that I have 

 been able to think out. I hope to improve 

 it on further trial, and I trust that others 

 will see and suggest improvements. The 

 table was printed in the American Chemical 

 Society's Journal for January, 1895. 



My method, following Lothar Meyer's 

 notable lecture before the German Chemical 

 Society, is to preface the course with a dis- 



knowledge is so incomplete and that which 

 we suppose we know is often so inaccurate. 

 It is sometimes difficult to assign an ele- 

 ment to its proper group and one is es- 

 pecially troubled by what Blanshard has 

 called ' Cross- Analogies.' 



I believe the atomic weight is to be ac- 

 cepted as the final arbiter of arrangement 

 in all cases. 



I have prepared a table in which what I 

 have regarded as the most prominent facts 

 of the Natural Sj'stem are presented. 



cussion of water as a compovmd, air as a 

 mixture, and the component elements. This 

 gives the three classes of elements, com- 

 pounds and mixtures, and some opportunity 

 for fundamental laws. Then the table is 

 given and its working explained. 



All of the elements are then described in 

 their proper order. 



Then their liydrogen compounds, followed 

 by the oxygen compounds. As each acid- 

 forming oxide is reached, its salts with all 

 the bases are given and described. 



