374 ACTUAL WORKING IN ORIGINAL RESEARCH. 



The ripening of a subject for research is affected by the 

 length of time which has elapsed since the subject was last 

 examined. The longer period of time a particular branch 

 of science has been neglected, the more ready usually it 

 is for a new investigation, because collateral branches of 

 science have advanced and left it behind ; several portions 

 of inorganic chemistry, that of the fluorides for example, 

 have been neglected, and are in this condition. Some 

 investigators avoid examining a subject which has been . 

 recently and extensively investigated ; it is, nevertheless, 

 evident that however recently a subject has been ex- 

 amined, if from any cause it is likely to yield new results, 

 it is in a fit state for further investigation. Great dis- 

 coveries ripen very slowly. Now that the great discovery 

 of spectrum analysis is a well-known truth, we can easily 

 perceive that the conditions of it were maturing by means 

 of successive researches, from the year 1802, when Wollas- 

 ton detected lines in the solar spectrum, and the year 

 1815, when Fraunhofer measured their positions, until 

 1859, when Kirchoff and Bunsen discovered the composi- 

 tion of the sun's atmosphere, and thus suddenly made 

 known its greatness. 



Another very uncertain point in selecting a subject is 

 the degree of probability of success in making the re- 

 search. In making new experiments, all kinds of obstacles 

 and new effects arise which we cannot foresee, and from 

 that and other causes, such as our limited means of detect- 

 ing effects, we rarely obtain from such experiments the 

 expected results. An investigator has not unfrequently 

 to advance some distance into a preliminary research 

 before he can determine whether or not he has really a 

 definite and new question upon which to work ; and he 

 often finds, after much expenditure of time and trouble, 

 that the supposed new phenomenon is only an old one in a 



