310 



SCIENCE. 



[N. S. Vol. I. No. 12. 



of gas which was certainly not oxygen nor 

 nitrogen. This proved to he the substance 

 about which the world is now talking. 



In this connection it is of great interest 

 to note that Cavendish, in 1785, probably 

 had this same substance before him free 

 from nitrogen. He performed the experi- 

 ment above described, and noticed the resi- 

 due, and says in regard to it: " We may 

 safely conclude that it is not more than yi^ 

 of the whole . ' ' This is very nearly the truth 

 as regards the relative amount of argon in 

 the air. 



(3) The most satisfactory method for ob- 

 taining the gas on the large scale consists 

 in passing ' atmosphere nitrogen ' over 

 highly-heated magnesium, which has the 

 power of uniting with nitrogen, while the 

 newly-discovered gas has not this power. 

 But, even by this method, the preparation 

 is very slow, and, up to the present, the gas 

 cannot easily be obtained in large quantity. 



The new substance is heavier than nitro- 

 gen. The density of hydrogen being taken 

 as unity, that of nitrogen is 14, of oxygen 

 16, and of argon 19.7. 



Perhaps the most remarkable property of 

 argon is its inertness. It has not been pos- 

 sible thus far to get it to combine with any 

 other substance, so that anything more than 

 a general comparison with known substances 

 is out of the question. It owes its name to 

 its inertness, argon being derived from two 

 Greek words signifying ' no work.' 



A determination of the ratio of the 

 specific heat of argon at constant pressure 

 to that at constant volume was determined 

 by means of observations on the velocity of 

 sound in the gas, and the ratio was found 

 to be 1.66. This is of much importance as 

 showing that the particles of which the gas 

 is made up act as individuals. If this con- 

 clusion is correct, it follows further that 

 argon must be either a single element or a 

 mixture of elements, and that, if it is a 

 single element, its atomic weight must be 



nearly 40, as its density is 19.7 and its atom 

 is identical with its molecule. 



Professor Crookes has studied the spectra 

 of argon and, in an article giving his results 

 in detail, he says : "I have found no other 

 spectrum-givhig gas or vapour jdeld spectra 

 at all like those of argon." * * * "As far, 

 therefore, as spectrum work can decide, the 

 verdict must, I think, be that Lord Rayleigh 

 and Professor Eamsay have added one, if 

 not two members to the family of elemen- 

 tary bodies." 



Finally, Professor Olszewski, of Cracow, 

 the well-known authority on the lique- 

 faction of gases has succeeded in both liqui- 

 fying and solidifying argon. It was found 

 to boil at 186.9° C, and to solidify at 189.6° 

 C, forming a mass resembling ice. 



To quote from Professor Ramsay's article 

 read before the Royal Societj' : " There is 

 evidence both for and against the hj-pothesis 

 that argon is a mixture : For, owing to Mr. 

 Crookes' observations of the dual character 

 of its spectrum ; against, because of Profes- 

 sor Olszewski's statement that it has a defi- 

 nite melting point, a definite boiling point, 

 and a definite critical temperature and pres- 

 sure ; and because, on compressing the gas 

 in pi-esence of its liquid, pressure remains 

 sensibly constant until all gas has condensed 

 to liquid." 



The above is a brief account of all that is 

 known about argon, and it would evidently 

 be prematui'e to indulge in speciilation re- 

 garding its position in the sj'stem. It may 

 as well be said at once that, if it is an ele- 

 ment or a mixture of elements, it will ap- 

 parentlj^ be dif&cult to find a place for it on 

 Mendele.efif's table. It will be well to await 

 developments before wonying on this ac- 

 count. If the time should ever come when 

 Mendeleeff's table has to be given up, some- 

 thing better will take its place. 



The suggestion has been made repeatedly 

 that argon is perhaps an allotropic form of 

 nitrogen. The strongest argument against 



