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Miss Agnes M. Clerke 



Eamsay and Dr. Travers, using the method of fractionation at low 

 temperatures. These successive discoveries suggested new and un- 

 expected problems, and offered fresh opportunities for pioneering 

 research. Argon, indeed, condenses with what may now be reckoned 

 as tolerable facility. M. Olszewski reduced a sample of gas sent 

 him by Professor Ramsay in 1895, to a colourless liquid, boiling under 

 atmospheric pressure at — 187° C, and one-and-a-half times denser 

 than water. It freezes into a transparent, glassy solid near — 190° C. 

 Helium, on the other hand, is more volatile than hydrogen. Its lique- 

 faction will accordingly give a lower temperature — will give, for it 

 has not yet been accomplished. This strange and rare ingredient of 

 our planet is the one accessible substance which remained invincibly 

 gaseous at the close of the nineteenth century ; there is no reason 

 to doubt, however, that liquid helium will, in the twentieth, form 

 one of the earliest trophies of research. Lord Kelvin's forecast of a 

 substance by means of which the distance to absolute zero would be 

 abridged from 15° to 5°, may then be realised. 



Inekt Components of Atmospheric Air. 



The " inert " components of air may be ranked as a distinct class 

 of bodies. They combine several exceptional peculiarities. They 

 resemble mercury in being monatomic : the physical unit or molecule, 

 is identical with the chemical unit, misnamed an atom ; hence their 

 density, as compared with hydrogen, is half their atomic weight. 

 They stand apart from all other known substances in being devoid of 

 chemical affinities ; to a very limited extent they are capable of being 

 dissolved by certain liquids, and absorbed by certain minerals ; but 

 they are strictly " non-valent " ; they form no true compounds. For 

 this reason, and because of the minute proportions in which they 

 occur, ordinary tests fail to disclose their presence. They have no 

 visible function in nature ; they exist as if by a survival of an earlier 

 order of things ; their appointed part was perhaps played while the 

 earth was still in the nebulous stage. They are wonderfully volatile 

 considering their densities, and for this reason are of especial interest 

 to cryogenists. The following little table gives the densities and 

 boiling-points, according to Eamsay and Travers, of the five members 

 of the group so far recognised : — 



