THE NEW CHEMISTRY. 393 



THE NEW CHEMISTEY, A DEVELOPMENT OF 



THE OLD. 



By M. M. PATTISON MUIE, F. K. S. E. 



IN a former paper * I endeavored shortly to summarize the more 

 important differences between that system of chemistry which 

 was founded on a so-called equivalent notation and the modern, or 

 atomic phase of the science. The general conclusion to which that 

 summary led was, that the old chemistry was empiric, while the new 

 is scientific ; but, as was there remarked, empiricism precedes science : 

 science is the natural development of empirical statements, and is not 

 to be regarded as entirely a new departure. 



Believing, as I do, that the old and new chemistry are essentially 

 opposed in their methods, I nevertheless am certain that the germs, 

 at least, of many of our modern chemical theories are to be found in 

 the statements, and even in the hypotheses, of the workers of half a 

 century since : and in the present paper I propose to trace, in a little 

 detail, what I believe to be a correct outline of the development of 

 two of the more important theories of modern chemistry, f 



The chemical views most in vogue before the strictly modern 

 epoch were founded more on considerations of the composition of 

 compounds than on the actions of these compounds. Dumas intro- 

 duced wider views by recalling the attention of chemists to the fact 

 that, in order to frame even a tolerably complete system of classifica- 

 tion, an answer must be given to the question, " What does this sub- 

 stance do ? " no less than to the other question, " Of what is this 

 substance composed ? " 



But, if we go back to the time before Lavoisier and his associates, 

 we find that the system then predominant in chemistry was founded 

 almost entirely on the reactions, and but to a very small extent on the 

 composition, of chemical substances. Chemists then busied themselves 

 continually with studying processes of chemical change ; only they 

 contented themselves with qualitative knowledge, and hence their 

 hypotheses were for the most part extremely vague and their facts 

 disconnected. John Joachim Beccher, born about 1630, seems to have 

 been the first to weave together the scattered chemical facts and 

 guesses into a consistent general theory, which was subsequently aug- 

 mented and defined by Stahl (1660-1734). 



Looking at the wonderful changes produced in substances by the 

 action of chemical force, the question arose, What happens when a 

 body undergoes chemical change ? and, as burning or combustion was 



* "Popular Science Review," January, 18*78. 



\ In the paper referred to, I briefly sketched the history of the development of the 

 older doctrine of "Equivalents" into the modern hypothesis of "Valency." 



