858 SIB B. C. BRODIE ON THE CALCULUS OF CHEMICAL OPERATIONS. 



the symbol of each chemical substance a distinct assertion is made as to the chemical 

 jMoperties of the substance, which any one is at liberty to test by an appeal to facts. 

 Now as no symbolic system similar to the present has yet been devised, and as this 

 system cannot be deduced from any existing system, every symbol not only makes an 

 assertion but expresses a discoveiy as to the chemical properties of the substance sym- 

 bolized. It is obvious, from the way in which the symbol is constructed, that the 

 properties symbolized are the properties of that system of chemical equations into 

 which the symbols enter, and from which the laws of the science are to be deduced. 

 The further development of these ideas must be reserved for another communication, 

 in which the nature of the numerical laws which are thus expressed will be more fully 

 considered. 



We may also regard the symbolic system as the expression, in the language of reason, 

 of those conceptions as to the composition of ponderable matter to which we are inevitably 

 brought by the contemplation of chemical phenomena. Our conclusions on this point 

 are so remarkable, and so contrary to anticipation, that doubtless we could never trust 

 them but for the simple and exact process by which they are deduced. Now the con- 

 ceptions which we form of the nature of the elemental bodies constitute the fundamental 

 theory of the science, for these conceptions comprise and determine every similar concep- 

 tion. The unit of the element hydrogen is here conceived of as a simple weight, and 

 symbolized by the letter a. That, to say the least, this view may be permitted 

 is proved by constructing the symbols of chemical substances upon this hypothesis. 

 There are, however, certain exceptions, be they real or apparent, in which this mode 

 of expression is impossible, and it wUl be seen on reference to the table of exceptions 

 (Sec. VIII. (4)) that this hypothesis rejects as inadmissible, not only the cases which 

 are rejected by the atomic theory, but those also which are rejected by the empirical 

 law of even numbers (p. 786). The symboHc system which is here given is the expression 

 of these laws, by the truth of which it must stand or fall. The imit of the element 

 mercury, and the units of several other metals, such as zinc, cadmium, and tin, so far as 

 our imperfect experience extends, appear to be analogous in this respect to hydrogen. 

 But these are the only elements of this simple composition. The units of a second 

 group, of which the element oxygen, symbolized as ^^, may be taken as a type, and to 

 which belong sulphur, d\ and selenium, X^, are composed of two identical simple weights, 

 and the facts of the science do not permit us to assume these units as otherwise composed. 

 Lastly, another group of elements appears in this system of a different and more complex 

 composition, to which group belong the elements chlorine a^-, bromine a/3', iodine uo)'^, 

 nitrogen av-, phosphorus (uip-y, arsenic (a^^)^, and in all probability numerous other 

 elements. The simplest view which, consistently with the fundamental hypothesis (Sec. 

 VII. Group 1 (1)), can be taken of the composition of these elements, regard being had 

 to the total system of chemical combinations, is that they are severally composed of a 

 unit of hydrogen and of two identical simple weights, as, for example, in the case of 

 chlorine, of the simple weight a and two of the simple weights symbolized by x^ so 



