THE PROGRESS AND DEVELOPMENT OF CHEMISTRY 

 DURING THE NINETEENTH CENTURY 



BY FRANK WIGGLESWORTH CLARKE 



[Frank Wigglesworth Clarke, Chief Chemist, U. S. Geological Survey, b. March 19, 

 1847, Boston, Mass. S.B. Harvard, 1867; D.Sc. Columbian, 1899; D.Sc. Victoria 

 University, England, 1903; Chevalier de la Legion d'Honneur, 1900. Professor 

 in Howard University, 1873-74; Professor of Chemistry and Physics, University 

 of Cincinnati, 187483; Honorary Curator of Minerals, U. S. National Museum, 

 and Professor of Mineral Chemistry, George Washington University. Fellow of 

 American Association for the Advancement of Science; Corresponding member 

 of British Association for the Advancement of Science; Corresponding member 

 of the Edinburgh Geological Society; member of the American Philosophical 

 Society, and Washington Academy of Sciences: Honorary member of Man- 

 chester Literary and Philosophical Society, and London Chemical Society; 

 Past-President of the American Chemical Society (1901). Author of Weights, 

 Measures, and Money of all Nations; Elementary Chemistry, and many bulletins 

 of the Geological Survey. About one hundred articles in scientific journals. Wilde 

 lecturer and medalist, Manchester, England, Literary and Phil. Society, 1903]. 



THE history of any science is a record of progress from empiricism 

 to philosophy; from isolated details to systematic knowledge. At 

 the outset, certain facts impress themselves upon the minds of men, 

 either because the observed phenomena are beneficial, or for the 

 opposite reason. Between the facts, the simpler and more obvious re- 

 lations of cause and effect are first noted, but only in the most super- 

 ficial way and without deliberate intention. By degrees, after many 

 wanderings along paths that lead nowhere, and in spite of countless 

 misinterpretations, mankind slowly accumulates a mass of data in 

 which something like unity begins to appear, and through which it 

 is seen that the universe is not a creature of caprice, but an existence 

 organized and orderly. This conception lies at the foundation of all 

 science; it is the one article of faith which the student dares not 

 doubt; for rational investigation would be impossible without it. 

 The belief in order, and the hope that we may discover its laws, inspire 

 all scientific researches. 



Speaking broadly, the development of science takes place in three 

 stages, which merge one into another and often overlap. First, there 

 is the collection of data; classification follows; and attempts at inter- 

 pretation come last of all. This is the logical course, which, however, 

 is not always followed. Premature speculations, efforts to determine 

 what the universe should be, are not unknown in the history of 

 human thought, nor have they been altogether futile. Hypotheses, 

 framed in advance of positive knowledge, help to stimulate investi- 

 gation, and so, despite their errors, lead us ultimately to the truth. 

 In reality, the three stages of growth coexist; experiment and specu- 

 lation go on side by side; and each one reinforces the others. 



At the beginning of the nineteenth century, chemistry was in a 



