1896-97.] 3^3 



hundred years, between 20 and 30 of the somewhere about 70 

 presently known have been discovered. Before the year 1789. 

 when Klaproth discovered Uranium and Zirconium, 21 at least 

 of those now known were undiscovered. Klaproth discovered 

 in 1789, Uranium and Zironium, in 1795 he discovered Titanium; 

 in 1798 Tellurium : and in 1804, Cerium. Vauquelin dis- 

 covered Glucinum and Chormium ; Tennant discovered Osmium 

 and Iridium ; and Wollaston discovered Palladium and Rhodium 

 all about the meeting of the centuries. In the 18th century 

 Boron, Chlorine, Iodine, Telurium Thorium, Cadmium, Lithium, 

 Magnesium, Vanadium, and Bromine were all discovered. 

 Hartwig, in his very interesting and instructive work on "The 

 Subterranean World," says, "of the metals, the knowledge of 

 the Ancients was limited to 7, namely : — Gold, Silver, Copper, 

 Tin, Iron, Lead, Mercury ; while now we know 56 ; most of 

 these new metals were unknown before the beginning of the 

 present century, nor can there be a doubt that further researches 

 will make us acquainted with many more metals whose existence 

 is still a secret to mankind." It was as late as 1894 tnat Lord 

 Raleigh and Professor Ramsay announced the finding of a new 

 gaseous element in the atmosphere ; Newth, however, says 

 whether this gas be a compound or a new element has not yet 

 been discovered. 



Some of you will probably be startled when I say that there 

 are presumably 100 Elements ; according to the last finding 

 and formulation of science it is so. Let me explain how this 

 has come about, although at present there are not more than 

 70 announced to the world. In 1864, Newlands was the first 

 to point out that if the elements be tabulated in the order of the 

 increase of their Atomic Weights the physical and chemical 

 properties belonging to the first seven reappear in the second 

 seven, ie. that the eighth corresponds to the first in these 

 characters ; the ninth to the second, and so on through the 

 whole 2 octaves ; and he applied to this relationship the name 

 of " The Law of Octaves?'' A more elaborate and systematic 

 representation of Newlands 1 Law was a little later on developed 



