42 



REPORT 1877. 



Metals 



Rare. 



Cadmium 56 



Cobalt 58-8* 



Bismuth 208 



Tungsten 184* 



Gold 196-7* 



Strontium 87-5* 



Uranium 120* 



Molybdenum 92* 



Glucinum 14* 



Titanium 50* 



Average 106-7. 



Very rare. 



Platinum 197 - 4* 



Palladium 106-5* 



Iridium 198* 



Osmium 199* 



Rhodium 104* 



(continued). 



Very rare (continued). 



Ruthenium 104* 



Lithium 7* 



Thallium 204* 



Vanadium 137* 



Cerium 92* 



Lanthanum 92* 



Didymium 96* 



Yttrium 68* 



Thorium 231-5* 



Niobium 97-6* 



Csesium 133* 



Rubidium 85* 



Indium 74* 



Tantalum 137-5* 



Tellurium 128* 



Zirconium 90* 



Average 122-9. 



The plentiful elements, whether non-metallic or metallic, have always low atomic 

 weights ; the less plentiful ones are generally heavier, and the very rare ones have 

 almost invariably high densities. 



This is still more strikingly the case with reference to the meteoric stones, which 

 are composed, almost without exception, of elementary substances which are light 

 when in the gaseous condition, viz. iron, nickel, chromium, oxygen, sulphur, 

 silicon, magnesium, calcium, sodium, carbon, hydrogen. 



Among the circumstances which interfere with the universality of this rule 

 are the great changes in density and volatility that are brought about by chemical 

 combination ; and the chemistry of the surface of our globe is but little guide to 

 the compounds that exist at the high temperature at which meteorites, and proba- 

 bly our own earth, were formed. 



Reasons were assigned for believing that the self-luminous heads of comets are 

 not composed of carbon vapour, but rather of incandescent compounds of that 

 substance. 



[Printed in cxtenso, Phil. Mag. November 1877-1 



Summary of the First Reduction of the Tidal Observations made by the recent 

 Arctic Expedition. By Prof. Hattgoton, F.R.S. 



Physical Properties of Solids and Liquids in Relation to the Earth's Structure. 



By Prof. Hennessy, F.R.S. 



On the Molecular Changes which take place in Iron and Steel while Pooling. 



By A. Mailock. 



On the Rate of Progression of Groups of Waves, and the Rate at which 

 Energy is transmitted by Wind. By Prof. Osborne Reynolds, F.B.S. 



* Atomic weight, 



