602 



SCIENCE. 



[N. S. Vol. VIII. No. 201. 



resistance thermometers are becoming use- 

 less, as the temperature of boiling hydrogen 

 is but a few degrees from the point where 

 the resistance of platinum would be practi- 

 cally nothing or the conductivity infinite. 



Several years ago I pondered on the con- 

 stitution of matter in what I ventured to 

 call the fourth state. I endeavored to probe 

 the tormenting mystery of the atom. What 

 is tlie atom ? Is a single atom in space 

 solid, liquid or gaseous ? Each of these 

 states involve ideas which can only pertain 

 to vast collections of atoms. Whether, like 

 Newton, we try to visualize an atom, as a 

 hard, spherical body, or, with Boscovitch 

 and Faraday, to regard it as a center of 

 force, or accept the vortex atom theory of 

 Lord Kelvin, an isolated atom is an un- 

 known entity difi&cult to conceive. The 

 properties of matter — solid, liquid, gaseous 

 — are due to molecules in a state of motion. 

 Therefore, matter as we know it involves 

 essentially a mode of motion ; and the atom 

 itself — intangible, invisible and inconceiv- 

 able — is its material basis, and may, indeed, 

 be styled the only true matter. The space 

 involved in the motions of atoms has no 

 more pretension to be called matter than 

 the sphere of influence of a body of riflemen 

 — the sphere filled with flying leaden mis- 

 siles — has to be called lead. Since what we 

 call matter essential!}' involves a mode of 

 motion, and since at the temperature of ab- 

 solute zero ail atomic motions would stop, 

 it follows that matter as we know it would 

 at that paralyzing temperature probably en- 

 tirely change its properties. Although a 

 discussion of the ultimate absolute proper- 

 ties of matter is purely speculative, it can 

 hardly be barren, considering that in our 

 laboratories we are now within moderate 

 distance of the absolute zero of temperature. 



I have dwelt on the value and importance 

 of nitrogen, but I must not omit to bring to 

 your notice those little known and curiously 

 related elements which during the past 



twelve months have been discovered and 

 partly described by Professor Eamsay and 

 Dr. Travers. For many years my own work 

 has been among what I may call the waste 

 heaps of the mineral elements. Professor 

 Eamsay is dealing with vagrant atoms of 

 an astral nature. During the course of the 

 present year he has announced the exist- 

 ence of no fewer than three new gases — 

 krypton, neon and metargon. Whether 

 these gases, chiefly known by their spectra, 

 are true, unalterable elements, or whether 

 they are compounded of other known or un- 

 known bodies, has yet to be proved. Pel- 

 low workers freely pay tribute to the pains- 

 taking zeal with which Professor Eamsay 

 has conducted a difficult research, and to 

 the philosophic subtlety brought to bear on 

 his investigations. But, like most discov- 

 erers, he has not escaped the flail of severe 

 criticism. 



There is still another claimant for celestial 

 honors. Professor Nasini tells us he has 

 discovered, in some volcanic gases at Poz- 

 zuoli, that hypothetical element, coronium, 

 supposed to cause the bright line 5316.9 in 

 the spectrum of the sun's corona. Analogy 

 points to its being lighter and more diffusible 

 than hydrogen, and a studj' of its properties 

 cannot fail to yield striking results. Still 

 awaiting discovery bj' the fortunate spectro- 

 scopist are the unknown celestial elements, 

 aurorium, with a characteristic line at 

 5570.7, and nebulum, having two bright 

 lines at 5007.05 and 4959.02. 



The fundamental discovery by Hertz, of 

 the electro -magnetic waves predicted more 

 than thirty years ago by Clerk Maxwell, 

 seems likely to develop in the direction of a 

 practical application which excites keen 

 interest— I mean the applicatioa to electric 

 signalling across moderate distances with- 

 out connecting wires. The feasibility of 

 this method of signalling has been demon- 

 strated by several experimenters at more 

 than one meeting of the British Association, 



