656 THE POPULAR SCIENCE MONTHLY. 



Chemical Dictionary, Basil Valentine's Triumphal Car of Anti- 

 mony, Stahl's Phlogistic Chemistry — thousands of essays and 

 treatises in Gottling's and Gehlen's periodicals, the works of Kir- 

 wan, Cavendish, etc. 



I am quite sure that this manner of reading was of no partic- 

 ular use so far as acquisition of exact knowledge is concerned, but 

 it developed in me the faculty, which is peculiar to chemists more 

 than to other natural philosophers, of thinking in terms of phe- 

 nomena ; it is not very easy to give a clear idea of phenomena to 

 any one who can not recall in his imagination a mental picture of 

 what he sees and hears, like the poet and artist for example. Most 

 closely akin is the peculiar power of the musician, who, while com- 

 posing, thinks in tones which are as much connected by laws as 

 the logically arranged conceptions in a conclusion or series of con- 

 clusions. There is in the chemist a form of thought by which all 

 ideas become visible to the mind as the strains of an imagined 

 piece of music. This form of thought is developed in Faraday in 

 the highest degree, whence it arises that to one who is not ac- 

 quainted with this method of thinking, his scientific works seem 

 barren and dry, and merely a series of researches strung together, 

 while his oral discourse, when he teaches or exj^lains, is intellect- 

 ual, elegant, and of wonderful clearness. 



The faculty of thinking in phenomena can only be cultivated 

 if the mind is constantly trained, and this was effected in my case 

 by my endeavoring to perform, so far as my means would allow 

 me, all the experiments whose description I read in the books. 

 These means were very limited, and hence it arose that, in order 

 to satisfy my inclination, I repeated such experiments as I was 

 able to make a countless number of times, until I ceased to see 

 anything new in the process, or till I knew thoroughly every as- 

 pect of the phenomenon which presented itself. The natural con- 

 sequence of this was the development of a memory of the sense, 

 that is to say of the sight, a clear perception of the resemblances 

 or differences of things or of phenomena, which afterward stood 

 me in good stead. 



One will easily understand this if one imagines, for instance, a 

 white or colored precipitate which is produced by mixing two 

 liquids ; it is formed either at once or after some time, it is cloudy 

 or of a curdy or gelatinous character, sandy or crystalline, dull or 

 bright, it deposits easily or slowly, etc. ; or if it is colored it has a 

 certain tint. Among the countless white precipitates each has 

 something peculiar to itself ; and when one has experience in this 

 sort of appearances, whatever one sees during an investigation at 

 once awakens the remembrance of what one has seen. The fol- 

 lowing example will make clear what I mean by sight or eye 

 memory : During our joint research on uric acid, Wohler one 



