TRANSACTION^ Of THE SECTIONS. 



41 



original volume. The rate of expansion per unit quantity of salt appears to in- 

 crease continually, but at first it is negative. 



The above numbers are given subject to correction by more elaborate experi- 

 ments which are now going on. The authors hope to extend the inquiry to other 

 salts. They have already examined the behaviour of anhydrous sulphate of soda ; 

 but with that salt no contraction whatever has been observed, the solutions expand 

 rapidly from the first. 



On some Points connected with the Chemical Constituents of the Solar System. 

 By Dr. J. H. Gladstone, F.E.S., President of the Chemical Society. 



The discoveries of the spectroscope, and the general advance of knowledge of the 

 heavenly bodies, have greatly confirmed the nebular theory of the creation of worlds. 

 Assuming a nebulous mass of many chemical elements gradually condensing to a 

 centre, how should we find these elements distributed ? The least volatile would 

 form the liquid or solid nucleus, while the others would arrange themselves accord- 

 ing to their volatility, condensing into cloud at various distances from the intensely 

 heated centre. Also, as Mr. Johnstone Stoney has shown, the gases would arrange 

 themselves according to their relative density, the lightest gases being at the out- 

 side. In neither case, however, would the separation of the constituents be perfect ; 

 for mechanical movements and diffusion will always cause some portions of the 

 less volatile bodies or denser gases to rise into the upper region. This is actually 

 what is taking place in the sun at present. 



Supposing the solar system to have been originally a great revolving nebula of 

 this description condensing to a central sun, and forming from its outer portions 

 smaller masses, such as the planets and their satellites, or the comets and meteorites, 

 we may expect these to consist principally of the more volatile or the lightest 

 elements with smaller portions of the less volatile or heavier ones. On arranging 

 the elements of which the earth is composed according to the known or presumed 

 density of their vapours, it is found that such is actually the case. 



Non-metallic Elements. 



Plentiful. 



Oxygen 10 



Silicon 28-5* 



Carbon 12* 



Hydrogen 1 



Sulphur 32 



Chlorine 35'5 



Nitrogen 14 



Average 19-8 



Not plentiful. 



Phosphorus , 62 



Fluorine 19* 



Bromine 80 



Boron 11* 



Iodine 127 



Selenium 79* 



Average 03. 



Metals. 



Plentiful. 



Aluminium 27-5* 



Calcium 40* 



Sodium 23* 



Magnesium 24* 



Potassium 39 



Iron 50* 



Manganese 55* 



Average 37*8 



Common. 



Barium 137* 



Zinc 325 



Lead 207* 



Arsenic 150 



Copper 03-5* 



Antimony , 122* 



Silver 108* 



Tin 118* 



( ihfomium 52'5* 



Mercury 100 



Nickel 58-8* 



Average 101'~> 



187- 



