TERMINOLOGY AND NOMENCLATURE. 427 



to have influenced the employment of the terms in common practice, 

 before the expediency had been pointed out of discriminatiu'j^ lh(!ni 

 philosophically. Every one would say that the refoi'm eff'ectcul by 

 Lavoisier and Guyton-Morveau in the language of chemistry consisted 

 in the introduction of a new nomenclature, not of a new terminology. 

 Linear, lanceolate, oval, or oblong, serrated, dentate, or crenate leaves, 

 are expressions forming part of the terminology of botany, while the 

 names " Viola odorata," and " Ulex europa^us," belong to its nomen- 

 clature. 



A nomenclature may be defined, the collection of the names of all 

 the Kinds with which any branch of knowledge is conversant, or more 

 properly, of all the lowest Kinds, or ivfimcc species, those which may 

 be subdivided indeed, but not into Kinds, and which generally accord 

 with what in natural history are termed simply species. Science 

 possesses two.spiendid examples of a systematic nomenclature ; that 

 of plants and animals, constructed by Linnjeus and his successors, and 

 that of chemistry, wiiich we owe to the illustrious group of chemists 

 who tlourislied in France towards the close of the eighteenth century. 

 In these two departments, not only has every known species, or lowest 

 Kind, a name assigned to it, but when new lowest Kinds are discovered, 

 names are at once given to them upon an uniform principle. In other 

 sciences the nomenclature is not at present constructed upon any sys- 

 tem, either because the species to be named are not mnnerous enough 

 to require one (as in geometry for example), or because no one has 

 yet suggested a suitable principle for such a system, as in mineralogy; 

 in which the want of a scientifically constructed nomenclature is now 

 the principal cause which retards the progress of the science. 



§ 5. A word which carries on its face that it belongs to a nomen- 

 clature, seems at first sight to differ from other concrete general names 

 in this — that its meaning does not reside in its connotation, in the 

 attributes implied in it, but in its denotation, that is, in the particular 

 group of things which it is appointed to designate ; and cannot, there- 

 fore, be unfolded by means of a definition, but must be made known in 

 another way. Mr. Whewell seems to incline to this opinion, which, 

 however, appears to me erroneous. Woids belonging to a nomencla- 

 ture differ, I conceive, from other words mainly in this, that besides 

 the ordinary connotation, they have a peculiar one of their own : 

 besides connoting certain attributes, they also connote that those attri- 

 butes are distinctive of a Kind. The tenn " peroxide of iron," for 

 example, belonging by its form to the systematic nomenclature of 

 chemistry, bears upon its face that it is the name of a peculiar Kind 

 of substance. It moreover connotes, like the name of any other class, 

 some portion of the properties common to the class; in this instance 

 the property of being a compound of iron and the largest dose of oxygen 

 with which iron will combine. These two things, the fact of being 

 such a compound, and the fact of being a Kind, constitute the conno- 

 tation of the name peroxide of iron. When we say of the sid)stance 

 before us, that it is the peroxide of iron, we thereby assert, first, that 

 it is a compound of iron and a maximum of oxygen, and next, that the 

 substance so composed is a peculiar Kind of substance. 



Now, this second part of the connotation of any word belonging to 

 a nomenclature is as essential a portion of its meaning as the first part, 



