382 



Dr. J. H. Gladstone on some Points connected 



Plentiful. 



Aluminium . . 

 Calcium .... 

 Sodium .... 

 Magnesium . . 

 Potassium . . 



Iron 



Manganese . . 

 Average . . 



Common. 



27-5 

 40 



23 

 24 

 39 



m 



55 



37-8 



137 



32-5 

 207 

 150 



63-5 

 122 



Very rare. 



56 



Platinum. . . 



. 197-4 



58-8 



Palladium . 



. 106-5 



208 



Iridium . , . 



. 198 



184 



Osmium . . . 



. 109 



196-7 



Rhodium. . . 



. 104 



87-5 



Ruthenium . 



. 104 



120 



Lithium . . . 



. 7 



92 



Thallium . . . 



. 204 



14 



Vanadium . 



. 137 



50 



Cerium 



. 92 



106-7 



Lanthanum . 



. 92 





Didymium , 



. 96 





Yttrium . . . 



. 68 





Thorium . . . 



. 231-5 





Niobium . . . 



. 97-6 





Caesium . . . 



. 133 





Rubidium . 



. 85 





Indium . . . 



74 





Tantalum . 



137-5 





Tellurium . 



128 





Zirconium . 



90 





Average . 



122-9 



Metals. 

 Rare. 



Cadmium 



Cobalt 



Bismuth 



Tungsten, 



Gold _ 



Strontium 



Uranium 



Molybdenum 



Glucinum 



Titanium . 

 cerium . '- Averao-e. 



Zinc 



Lead 



Arsenic . 

 Copper. . . 

 Antimony 



Silver 108 



Tin 118 



Chromium . . 62-5 



Mercury 100 



Nickel 58-8 



Average . . 104*5 



Note. — The numbers represent the atomic weights. It is very possible 

 that the vapour-densities of many of the metals may really be represented 

 by these numbers divided by two, as we know it to be in tlie case of zinc 

 and others. If this be so, it will not aiFect the general conclusions. 



It vvdll be seen that the average density of those non-metallic 

 elements which are plentiful is 19*8, against 63*0 as the den- 

 sity of the rarer ones. This contrast is still more striking in 

 regard to the metals : — those in the list headed ''plentiful" 

 having invariably low vapour-densities, with the average of 

 37*8; those denominated "common" being nearly always 

 higher, with the average of 104'5 ; those denominated ''rare" 

 averaging 106*7 ; while the very rare metals have almost in- 

 variably high atomic weights, giving the higher average of 

 122*9. This classification, however, scarcely represents the 

 whole truth, especially in regard to the metals ; for as far as we 

 are acquainted with the constituents of the earth, the first six 

 or seven metals are incomparably more abundant than the 

 remainder, while most of the heaviest metals exist but in 

 merest traces. It may also be remarked that not one of the 

 very rare metals is sufficiently volatile for its vapour-density 

 to have been taken. This is quite in accordance with theory, 

 showing that all those elements of which the great mass of 

 the earth is composed are of low density when in the gaseous 

 condition, and that they are mixed with much smaller quan- 

 tities of bodies which as a rule give heavier and more conden- 

 sable vapours. 



