280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 3 



lion tons of water from freezing to boiling temperatures. Such 

 are the stores of atomic energy. Let us see how this works in refer- 

 ence to the preceding case of transmutation. 



A certain isotope of lithium has atomic weight 7.008, and a proton 

 has atomic weight 1.0072. Their sum is 8.0152. This splits up into 

 2 helium nuclei each of mass 4.00. Thus the product nuclei have 

 mass 0.0152 less than the original combining nuclei. This lost mass 

 is converted into energy according to equation (4). To calculate 

 the energy, we first change 0.0152 from chemical units of atomic 

 weight into grams, which gives a loss of 2.88 (lO)-^^ g for every 

 individual transmutation process. According to equation (4) this 

 is equivalent to the liberation of 25.9 (10)-° ergs. This is the 

 amount of energy which would be acquired by an electron in mov- 

 ing through a potential difference of 16,300,000 volts — which is what 

 we mean by 16-million-volt energy. 



Thus, by considering various atomic weights in connection with 

 Einstein's equation, we gain a clue as to which atoms may be ex- 

 pected to be relatively easily transmuted, and what the resultant 

 energy will be. 



This brings me to the final stage of the discussion. With these 

 promising beginnings, ju^t recently achieved after centuries of 

 effort, the alchemist takes renewed hope and enthusiasm in his quest. 

 He now has some knowledge of how to plan his attack on the atom. 

 He has at least two proven weapons, or rather missiles to hurl at 

 atoms, viz, alpha particles from radioactive sources, and ions, sixch 

 as protons, which are given tremendous speeds with high voltages. 

 He will continue to batter away at the atoms with both of these. 

 Of the two, the high-voltage ion source is the most intriguing on 

 account of the almost unlimited possibilities of high speeds, through 

 the development of high-voltage generators, and of high intensities 

 through the development of potent sources of protons or other types 

 of ions. 



It is this feature which gives particular interest to the various new 

 types of high-voltage generators which are now being developed in 

 various laboratories. Most promising are those of Lawrence at the 

 University of California and of Van de Graaff at Princeton and the 

 Massachusetts Institute of Technology. 



Lawrence does not actually use or develop a very high voltage, but 

 he uses a moderate voltage to give a succession of pushes to the ions 

 until they get to going with speeds which have considerably exceeded 

 a million volts, and which may well reach 5 million volts with 

 apparatus under construction. Without going into technical details, 

 the idea may be conveyed by likening the operation to a child in a 

 swing. By properly synchronizing the pushes, the child may be 



