1889,] on an attempt to appli/ to Chemistrij, &c. 523 



attain to that chie^ and fundamental object — the comprehension of 

 isomerism in hydrocarbon compounds, and the forecasting of the 

 existence of combinations as yet unknown, by which the ediace 

 raised by structiu-al teaching is strengthened and supported. Besides, 

 and I count this for a circumstance of special importance, the process 

 which I advocate will make no diiference in those special cases which 

 have been already so well worked out, such as, for example, the 

 isomerism of the hydrocarbons and alcohols, even to the extent of not 

 interfering with the nomenclature which has been adopted, and the 

 structural system will retain all the glory of having worked up, in a 

 thoroughly scientific manner, the store of information which Gerhardt 

 had accumulated about the middle of the fifties, and the still higher 

 glory of establishing the rational synthesis of organic substances. 

 Nothing will be lost to the structural doctrine, except its statical 

 origin ; and as soon as it will embrace the dynamic principles of 

 Newton, and suffer itself to be guided by them, I believe that we shall 

 attain, for chemistry, that unity of principle which is now wanting. 

 Many an adept will be attracted to that brilliant and fascinating 

 enterprise, the penetration into the unseen world of the kinetic rela- 

 tions of atoms, to the study of which the last twenty-five years hare 

 contributed so much labour and such high inventive faculties. 



D'Alembert found in mechanics, that if inertia be taken to repre- 

 sent force, dynamic equations may be applied to statical questions 

 which are thereby rendered more simple and more easily understood. 



The structural doctrine in chemistry has unconsciously followed 

 the same course, and therefore its terms are easily adopted ; they may 

 retain their present forms provided that a truly dynamical, that is to 

 say, Newtonian meaning be ascribed to them. 



Before finishing my task and demonstrating the possibility of 

 adapting structural doctrines to the dynamics of Newton, I consider 

 it indispensable to touch on one question which naturally arises, and 

 which I have heard discussed more than once. If bromine, the atom 

 of which is eighty times heavier than that of hydrogen, takes the 

 place of hydrogen, it would seem that the whole system of dynamic 

 equilibrium must be destroyed. 



Without entering into the minute analysis of this question, I 

 think it will be sufficient to examine it by the light of two well- 

 known phenomena, one of which will be found in the department of 

 chemistry, and the other in that of celestial mechanics, and both will 

 serve to demonstrate the existence of that unity in the plan of 

 creation, which is a consequence of the Newtonian doctrines. 

 Experiments demonstrate that when a heavy element is substituted 

 for a light one, in a chemical compound — an atom of magnesium in 

 the oxide of that metal, for example, for mercury, the atom of which 

 is 8i times heavier — the chief chemical characteristics or properties 

 are generally though not always preserved. 



The substitution of silver for hydrogen, than which it is 

 108 times heavier, does not aifect all the properties of the substance, 



Vol. XII. (No. 83.) 2 n 



