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XVI. Remarks on Sir Benjamin Brodie's System of Chemical 

 Notation, By Alexander Crum Brown, M.D., D.Sc* 



THE System of Chemical Notation introduced by Sir Ben- 

 jamin Brodie, in his paper " On the Calculus of Chemical 

 Operations," is so interesting from its apparent novelty, and 

 from the great ingenuity its author has shown in its construc- 

 tion, that I hope the following remarks upon it may not be con- 

 sidered out of place. 



In the introduction, the author is, I think, unnecessarily 

 severe in his remarks upon those chemists who use atomic or 

 even graphic formulae. While there can be no doubt that phy- 

 sical research points to a molecular constitution of matter, it is 

 perfectly indifferent to a chemist whether his symbols represent 

 atoms or units; and graphic formulae would be as useful as 

 they now are, were it conclusively proved that matter is con- 

 tinuous. 



In proceeding to the examination of the notation itself, it is 

 necessary to observe, in the first place, that it is a system for 

 expressing by a formula (1) the weight of a unit (or as most 

 chemists would call it, a molecule) of a homogeneous chemical 

 substance, and (2) the composition of the substance. It is 

 therefore, as far as the author has developed it in his first paper, 

 a system of empirical formulae. 



In Sections I.- VI. inclusive the author lays down the general 

 principles applicable to the formation of such a system. These 

 principles apply as well to the system at present in use as to that 

 proposed (for H, 0, N, C, &c. may be called prime factors as 

 well as atoms), and one great benefit which we may expect from 

 the publication of Sir Benjamin's paper is a greater consistency 

 and uniformity in the use of symbols. 



The assumption (as far as I can see quite unnecessary) of the 

 distributive law of multiplication leads to some mathematical 

 difficulties : thus y + y l =yy l ', but x(y -f y x ) is not equal to xyy ls 

 for the former is xy + xy l = % 2 yy v Now we know no analytical 

 system in which a = b does not imply fa =fb, f being a functional 

 operator, unless /has more than one value (as \/, sin _i , &c.) ; 

 and this is plainly not the case here. 



In Section III. the author gives three modes in which the 

 chemical symbol 1 may originate. I have some difficulty in 

 seeing how these differ from one another. The first is xy=x, 

 where y is the symbol of no weight; the second is x°= 1 ; and 



x 

 the third - = 1. Now the third seems to include the other two. 



oo 



* Communicated by the Author. 

 Phil. Mag. S. 4. Vol. 34 No, 228. Aug. 1867. K 



