442 OPERATIONS SUBSIDIARY TO INDUCTION. 



there is one property, the chemical composition, which is of itself 

 sufficient to distinguish the Kind ; of itself a sure mark of all the other 

 properties of the compound. All that was needful, therefore, was to 

 make the name of every compound express, on the first hearing, its 

 chemical composition ; that is, to form the name of the compound, in 

 some uniform inanner, from the names of the simple suhstances which 

 enter into it as elements. This was done, most skillfully and success- 

 fully, by the French chemists. The only thing left unexpressed by 

 them was the exact proportion in which the elements were combined; 

 and even this, since the establishment of the atomic theory, it has 

 been found possible to express by a simple adaptation of their 

 phraseology. 



But where the characters which must be taken into consideration in 

 order sufficiently to designate the Kind, are too numerous to be all 

 signified in the derivation of the name, and where no one of them is of 

 such preponderant importance as to justify its being singled out to be 

 so indicated, we may avail ourselves of a subsidiary resource. Though 

 we cannot indicate the distinctive properties of the kind, we may indi- 

 cate its nearest natural affinities, by incorporating into its name the 

 name of the proximate natural group of which it is one of the species. 

 On this principle is founded the admirable binary nomenclature of 

 botany and zoology. In this nomenclature the name of every species 

 consists of the name of the genus, or natural group next above it, with 

 a word added to distinguish the particular species. This last jjortion 

 of the compound name is sometimes taken from some one of the pecu- 

 liarities in which that species diffex's from others of the genus ; as Cle- 

 matis integrifolia, Potentilla alha, Yio\ci palustris, Axtc\n\?,m vulgaris ; 

 sometimes from a circumstance of a historical nature, as Narcissus ^oe- 

 ticus, Potentilla tormcntilla (indicating that the plant was formerly 

 known by the latter name), Exacum Candollii (from the fact that De 

 Gandolle was its first discoverer) ; and sometimes the word is purely 

 conventional, as Thlaspi bursa-pastoris, Ranunculus thora : it is of little 

 consequence which ; since the second, or as it is usually called the spe- 

 cific name, could, at most, express, independently of convention, no 

 more than a very small portion of the connotation of the term. But 

 by adding to this the name of the superior genus, we make the best 

 amends we can for the impossibility of so contriving the name as to 

 express all the distinctive characters of the Kind. We make it, at all 

 events, express as many of those characters as are common to the prox- 

 imate natural gToup in which the Kind is included. If even those 

 common characters are so numerous or so little familiar as to require a 

 further extension of the same resource, we might, instead of a binary, 

 adopt a ternary nomenclature, employing not only the name of the 

 genus, but that of the next natural group in order of generality above 

 the genus, commonly called the Family. This was done in the mine- 

 ralogical nomenclature proposed by Professor Mohs. " The names 

 framed by him were," says Mr. Whewell,* "not composed of two, 

 but of three elements, designating respectively the Species, the Genus, 

 and the Order; thus he has such species as PJioiyihohedral Lime Ha- 

 loide, Octahedral Fluor Haloide, Prismatic Hal Baryte.'" The binary 

 construction, however, has been found sufficient in botany and zoology, 



* Aphorisms concerning tlie Language of Science, p. Ixiv. 



