44 THOUGHTS ON NATURAL PHILOSOPHY. 



others we get a third of that speed. Let us take 

 the lesser of these figures, that of 100,000 kilometres 

 per second, and endeavour on that basis to calculate 

 the energy that would result from the complete dis- 

 sociation of one gramme of any matter we please. 



Let us take, for instance, a copper one centime 

 piece, weighing, as is well known, one gramme, and 

 let us suppose that by accelerating the rapidity of its 

 dissociation we could succeed in totally dissociat- 

 ing it. 



The kinetic energy possessed by a body in motion 

 being equal to half the product of its mass by the 

 square of its speed, an easy calculation gives the 

 power which the particles of this gramme of matter, 

 animated by the speed w r e have supposed, would 

 represent. We have, in fact, 



o.ooi k i 2 _5io thousand millions of 



9.81 2 100,000,000 kilogrammetres, 



figures which correspond to about six thousand eight 

 hundred million horse-power if this gramme of matter 

 were stopped in a second. This amount of energy, 

 suitably disposed, would be sufficient to work a goods 

 train on a horizontal line equal in length to a little 

 over four times and a quarter the circumference of 

 the earth. 



To send this same train over this distance by 

 means of coal would take 2,830,000 kilogrammes, 

 which at 24 francs a ton would necessitate an ex- 

 penditure of about 68,000 francs. This amount of 

 68,000 francs represents therefore the commercial 

 value of the intra-atomic energy contained in a one- 

 centime coin. 



