RADIUM AND ITS PRODUCTS 



CHEMISTRY and physics are experimental sciences; and 

 those who are engaged in attempting to enlarge the 

 boundaries of science by experiment are generally un- 

 willing to publish speculations ; for they have learned, by 

 long experience, that it is unsafe to anticipate events. It 

 is true they must make certain theories and hypotheses. 

 They must form some kind of mental picture of the 

 relations between the phenomena which they are trying 

 to investigate, else their experiments would be made at 

 random and without connection. Progress is made by 

 trial and failure; the failures are generally a hundred 

 times more numerous than the successes; yet they 

 are usually left unchronicled. The reason is that the 

 investigator feels that even though he has failed in 

 achieving an expected result, some other more fortunate 

 experimenter may succeed, and it would be unwise to 

 discourage his attempts. 



In framing his suppositions, the investigator has a 

 choice of five kinds; they have been classified by Dr. 

 Johnstone Stoney. ' A theory is a supposition which we 

 hope to be true, a hypothesis is a supposition which we 

 expect to be useful ; fictions belong to the realm of art ; if 

 made to intrude elsewhere, they become either make- 

 believes or mistakes/ Now the ' man in the street/ when 

 he thinks of science at all, hopes for a theory ; whereas 

 the investigator is generally contented with a hypothesis, 

 and it is only after forming and rejecting numerous hypo- 



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