THE KEVIVAL OP INORGANIC CHEMISTRY. 299 



geologist de Chancourtois, using the newer and now adopted atomic 

 weights, arranged the elements in a spiral or helical form around a 

 cylinder, in ascending order, and was led to the conclusion that the 

 "properties of bodies are properties of the numbers,'' a vague state- 

 ment of the now familiar phrase that the properties of the elements are 

 functions of their atomic weights. As already mentioned, he was 

 followed closely by Newlands, whose work, however, met with but 

 slight recognition. Time is wanting to show how, in the period 1S61- 

 1869 the Periodic Law was developed by the labors of Newlands, and 

 more especially of Lothar Meyer and Meudelejeff, working independ- 

 ently. It affords an interesting example of how a great idea is devel- 

 oped about the same time in the minds of several men working 

 independently and unknown to each other. In 1871 Meudelejeff pub- 

 lished a table which shows the Periodic Law essentially as we find it 

 to-day, the only changes consisting in the addition of a few* newly 

 discovered elements and in placing a few of the older elements in their 

 proper positions, as a result of more accurate atomic weight determi- 

 nations. 



The period 1863-1870 was, therefore, of the greatest importance for 

 inorganic chemistry, as it saw the development of the idea that the 

 properties of the elements are periodic functions of their atomic weights. 

 The time which has since elapsed has been even more fruitful than any 

 previous period in speculations, having for their object the finding of 

 mathematical relations between the atomic weights and in theories of 

 the evolution of matter from one or two primal constituents. Many 

 modifications of the periodic scheme have been devised, but they pre- 

 sent but few or no advantages over the simple arrangement of Meu- 

 delejeff and Lothar Meyer. The great fact still remains, unmodified and 

 unimproved, that it the elements be arranged in the order of increasing 

 atomic weights there is a recurrence of the properties of elements lower 

 in the scale — in short, that these properties are periodic functions of 

 the atomic weights. 



The discovery of the new group of inert gases, helium, neon, argon, 

 and xenon, with perhaps krypton and metargon, has not modified our 

 idea of the Periodic Law essentially. They appear to fit well into the 

 system, and it is now only remarkable that their existence was not 

 surmised by Mendelejeff, who so successfully predicted several theu 

 unknown elements. Although the periodic system is even to-day the 

 object of attack by a few chemists, who appear, to be blinded by its 

 unquestioned defects to the obvious truths which it expresses, it may 

 be safely said that the great central fact of the periodicity in the prop- 

 erties of the elements is just as firmly established as the law of gravi- 

 tation, and that, whatever modifications may have to be made in the 

 scheme as a whole, this central fact will never be done away with. 

 The atomic theory may be supplanted by something better, but its 

 successor will equally have to take account of the stoichiometrical 



