1920] on Researches at High Pressures and Temperatures 17 



more massive component of the binary star S. Hercules to be 

 360.000,000 tons per square inch. 



Again the densities of the brighter components of the stars o1 

 Cassiopeia? and B 612 are estimated by Opik to be about that of iron ; 

 and if we assume their diameter to be the same as that of the sun, 

 and that each has an initial velocity in space not greater than 

 30 miles per second, and that they directly collide, then, owing to 

 their mutual attraction, Jeans calculates that their velocity will have 

 increased to 450 miles per second, and the pressures in the centre as 

 they strike and flatten would be of the order of 1,000,000,000 tons 

 per square inch. He also estimates that the heat equivalent of the 

 energy would be sufficient to vaporize the whole mass 100,000 times 

 over. This immense pressure would be maintained for many minutes, 

 perhaps for half an hour. 



Let us consider what is the greatest pressure that can be pro- 

 duced artificially. If the German gun which bombarded Paris were 

 loaded with a solid steel projectile, somewhat shorter and lighter 

 than the one actually used, a muzzle velocity of about 6000 feet 

 seconds might be reached (many years ago Sir Andrew Xoble had 

 reached 5000 feet seconds) ; and if it was fired into a tapered hole 

 as I have described, in a large block of steel, this would give the 

 greatest instantaneous pressure that can be produced artificially, as 

 far as we at present know, viz. about 7000 tons per square inch. 

 This is only about 1-150,000 part of that possible by the collision of 

 the largest stars. 



As to the temperature and conditions of matter under these 

 intense pressures exterpolation from known data is valueless. We 

 have no knowledge of the co-efficients of compressibility of matter 

 under these conditions, or of its specific heat — what may lie the 

 effect on the atom, and will elements under such conditions be 

 transformed into others of higher atomic weight ? 



Some of us may recall that in 1888 the lecturer, after describing 

 in this room the experiment in which oxygen at atmospheric pressure 

 was passed in close contact with a platinum surface heated by the 

 oxyhydrogen burner to nearly its melting point, and then immediately 

 cooled by contact in water, said : " In this experiment ozone is 

 formed by the action of a high temperature, owing to the dissociation 

 of the oxygen molecules and their partial recombination into the 

 more complex molecules of ozone. We may conceive it not improl >able 

 that some of the elementary bodies might be formed somewhat like 

 the ozone in the above experiment, but at very high temperatures, 

 by the collocation of certain dissociated constituents and with the 

 simultaneous absorption of heat." 



It seems indeed probable that the centres of the great stars and 



stars in* collision may be the laboratories where the elements as they 



gradually degenerate are being continually regenerated into others of 



higher intrinsic energv, and where endothermic processes such as the 



1 Vol. XXIII. (No. 114) 



