July 31, 1896 ] 



SCIENCE. 



131 



voice of the great Berthollet was, it is 

 true, raised in a demand for the study of 

 the physical aspect of chemical change, 

 while Avogadro explained the meaning of 

 Gay-Lussac's and Dalton's discoveries of the 

 simple relationships between combining gas 

 volumes, but both were unheeded, for the 

 chemical field was not ripe for such devel- 

 opment. During the latter part of the life 

 of Berzelius we find such investigators as 

 Wohler, Liebig and Dumas busily engaged 

 in building a new edifice of structural or- 

 ganic chemistry, and at the same time the 

 tendency showed itself to unduly emphasize 

 the importance of chemical symbols, for the 

 theory of compound radicles with its numer- 

 ous variations, held most men in its grasp. 

 Chemical bodies were classified according 

 to arbitrarily constructed formulae, regard- 

 less oftentimes of obvious family relation- 

 ships; theory began to outrank exact 

 observation; and, even with so careful an 

 experimenter as Berzelius, chemical formu- 

 lation began to distort and replace ascer- 

 tained facts. This chaos, produced by the 

 clashing of minds, all equally qualified to 

 dictate in the chemical field, was further 

 heightened by the lack of any reliable 

 scientific basis for the determination of 

 atomic weights; there were almost as many 

 systems as there were chemists. It was 

 only after 1850, when Cannizzaro success- 

 fully revised Avogadro's hypothesis, when 

 the laws of thermodynamics were estab- 

 lished and when the impulse toward a log- 

 ical system of atomic weights was given, 

 that some advance toward order was made. 

 From this time on, owing to the labors of 

 Kolbe, Williamson, Strecker, Gerhardt, 

 Laurent and finally Kekule, our present 

 views of valence and structural chemistry 

 began to take the place of former confusion. 

 With the advent of the definite theory of 

 quadrivalence of carbon, at first advanced 

 by Kekule simply as a means of classifica- 

 tion, a basis for united action was given 



which was eagerly seized on by all of the 

 workers in the chemical field. Never be- 

 fore had so simple a theory been adopted, 

 and never before had one appeared which 

 so heartily met with the approval of most 

 men. So easily comprehended, indeed, 

 were these views that, as a logical conse- 

 quence, chemists were carried too far in 

 their enthusiasm : if the tetravalence of 

 carbon was established, why was not a 

 constant valence true of all other elements ? 

 Acting on the impulse, the classification 

 into monads, diads and triads, etc., was 

 made, often in utter disregard of easily ob- 

 served facts. Theories were once more 

 confused with the facts from which they were 

 deduced, and an arbitrary method of chem- 

 ical teaching, far removed from the basis on 

 which physics rested, was inaugurated. 

 The chemical symbol and chemical equa- 

 tion were given a rank and place far above 

 their merits; and, as a consequence, the 

 scientific axiom that all theoretical deduc- 

 tions must be founded upon carefully ob- 

 served facts was too frequently lost sight of. 

 Even Mendelejefi" and Lothar Meyer, in 

 their Development of Newland's Periodic 

 System, were often tempted to force dog- 

 matic classification upon the chemical 

 world. This tendency in chemical teaching 

 has continued to the present day, and along 

 with it we still have the undue emphasis 

 laid upon analytical chemistry, a remnant 

 of Berzelius's time, although the chemical 

 field has been so widened that many other 

 branches of the science have far outgrown 

 the latter in relative importance. 



Taking heed of the errors of the past, it 

 is time to bring the teaching of chemistry 

 to a purely scientific basis of experimental 

 observation, to omit theoretical deductions, 

 especially the atomic theory, until such a 

 time as the pupil has at his disposal suffi- 

 cient material to give it a definite basis to 

 rest upon. 



There are two laws which are fundamen- 



