782 SIR B. C. BRODIE ON THE CALCULUS OF CHEMICAL 0PEEATI0N8. 



mystic spirit of alchemy, and the subject has never ceased to occupy a prominent posi- 

 tion in chemical philosophy. However, the development of our symbolic system has by 

 no means kept pace with the general progress of the science. Indeed no essential 

 imin-ovement in the method has been effected since its first invention by Berzelius; 

 and though this notation has doubtless afforded much aid to memory, and through 

 memory incidentally to reasoning, yet it is difficult to point to even one discovery in 

 the science, for which we are indebted to symbolic operations. In this respect chemical 

 symbols present a marked contrast to other symbolic systems. The application of 

 symbols to geometry and mechanics immediately led to the discovery of important 

 truths, which were folloAved by the most original and unexpected development of the 

 symbolic method itself. A very slight examination, however, of our present system is 

 sufficient to render evident, that not only are the symbols of the chemist wanting in 

 precision, but that they are of a totally different order from those symbols the employ- 

 ment of which has been attended with such great results. 



The question of chemical symbols cannot well be separated from the consideration of 

 the hypothesis which is expressed in them. The actual theory of chemistiy is based upon 

 the atomic theory of Dalton, and in the ' New System of Chemical Philosophy ' may be 

 found the germ whence our notation has been developed. According to the views of 

 this eminent philosopher, the ponderable matter of any portion of the elemental bodies 

 is assumed to consist of a vast yet finite number of minute, indivisible, and homogeneous 

 particles or atoms, by the varied combinations of which all other substances may be 

 produced. With the object of elucidating his theory, Dalton gave (in the plates at the 

 end of his work) a kind of pictorial representation of the nature of matter from the 

 point of view of his hypothesis. He represented the atoms of the elements by single 

 circles with a characteristic mark, and the molecules of compound substances by systems 

 of circles placed side by side in the figure, as the atoms were supposed to be placed in 

 nature. Such pictures, for instance, are the following*, by which he figured oxygen, 

 hydrogen, nitrogen, water, ammonia, nitric and acetic acids. 



Oxygen Q 



Hydrogen .... (T\ 



Nitrogen .... rr\ 



Water (T)Q 



Ammonia .... (TyT) 



Nitric acid . . fT) 



Acetic acid . .' V<3R>< ' 

 * See ' New System of Chemical Philosophy,' part 1, p. 219. 



