264 MODERN SCIENCE READER 



The fundamental postulate of ancient and medieval 

 alchemy was that metals are chemical compounds. It was 

 not an extravagant belief ; the facts of technical experience 

 accorded with it; its truth appeared incontestable until 

 Lavoisier published, in 1787, his Methode de Nomenclature 

 Chimique. A treatise on metallic dissociation was accord- 

 ingly adjudged a prize by the Copenhagen Academy of 

 Sciences in 1780, and G. G. Kastner, professor of chemistry 

 at the University of Heidelberg, ignorant or negligent of 

 Lavoisier's work, suggested in 1806 the feasibility of fabri- 

 cating quicksilver out of phosphorus and charcoal. 1 The 

 integrity of the atom, on the other hand, is the most essen- 

 tial principle of modern chemistry, and metals are distinc- 

 tively " elementary " in the nineteenth-century sense. That 

 is to say, they are indecomposable by force or skill. Their 

 atoms are veritable chemical units. Yet they have long 

 been suspected to be physically divisible under conditions 

 different from the ordinary. They show wide diversities 

 in weight, the lead-atom, for instance, being nearly thirty 

 times heavier than the lithium atom. Moreover, the atomic 

 weights, to the number of nearly eighty, fall into related 

 series, intimating the action, it is thought, of some law by 

 which indefinitely small particles have variously collected 

 into connected systems. The subtlety and sensitiveness, 

 too, of luminous vibrations, together with the manifold 

 intricacies of spectral effects, lent countenance to the opin- 

 ion that atoms might be elaborate pieces of mechanism, 

 their parts being probably in rapid motion. The paradox- 

 ical hypothesis that atoms have parts has now become a 

 recognized truth of science. They are complex aggregates, 

 and the aggregates are liable to go to pieces. This is the 

 secret of radio-activity. This was the meaning of the 

 actinic effects, due to some effluvium from a salt of uranium, 

 detected by M. Henri Becquerel in 1896. They implicitly 

 announced what was little short of a scientific revolution. 



How far it will be carried none can foretell. As yet we 

 *E. Schultze, Das Letzte Aufflackern der Alchemic, page 42. 



