438 Rev. W. Whewell on the Employment 



hope that the system so reformed might obtain general circula- 

 tion ; since the question undoubtedly is, or soon will be, not 

 whether or no we shall employ notation in chemistry, but 

 whether we shall use a bad and incongruous, or a consistent 

 and regular notation. 



I shall now endeavour to show the necessity and the ad- 

 vantages of a proper use of symbols in this science, and the 

 inconveniences of those at present in use on the continent. 



In many compounds of two ingredients there is no difficulty 

 in expressing the composition clearly and simply, by means of 

 the usual language of chemistry. We have carbonate, 6icar- 

 bonate and sesquicarbonaie of soda ; where we may observe, 

 however, that the possibility of expressing the latter compound 

 in this form, depends upon the accident of there being a Latin 

 term possessing the signification of one and a half; and that 

 if we had two atoms and a half of acid, we should be at a loss 

 how to devise a corresponding term. In the same manner 

 \ve have sulphurets, 6i'sulphurets, </wac?nsulphurets ; protoxide, 

 deutoxide, frifoxide ; terms which sufficiently express the con- 

 stitution of the compounds to which they refer. 



But the usual nomenclature is, even in such cases, imper- 

 fect. The words hyposulphite, sulphite, sulphate, are defec- 

 tive, in not showing the relative quantity of oxygen in the 

 acid ; and, moreover, such terms are liable to become impro- 

 per by the discovery of new compounds. The same may be 

 said of such expressions as peroxide, persulphuret. 



Nor is this nomenclature capable of extending itself, in 

 virtue of its own rules, in proportion as discovery extends. If 

 new combinations of manganese and oxygen should hereafter 

 be discovered, they must receive arbitrary, and probably ano- 

 malous designations. The oxide, deutoxide, peroxide, man- 

 ganesious and manganesic acid, do not at all obviously refer 

 to compounds, in which the proportions of oxygen are 1, 1J, 

 2, 3, 4 ; and if we should find a combination in which the 

 proportion of acid is 2J or 3J, there is no denomination ready 

 for it, nor would it be easy to find a good one. This applies 

 equally to very many cases. 



In other cases phrases are used, as the sulphato-tricarbonafe 

 of lead for instance, which, though capable of a right interpre- 



