268 OPERATIONS SUBSIDIARY TO INDUCTION. 



the same direction, consistently with the most tho- 

 rough knowledge of their meaning; arising from the 

 fact, that the number of things known to us, and of 

 which we feel a desire to speak, multiply faster than 

 the names for them. Except on subjects for which 

 there has been constructed a scientific terminology, 

 with which unscientific persons do not meddle, great 

 difficulty is generally found in bringing a new name 

 into use; and independently of that difficulty, it is 

 natural to prefer giving to a new object a name which 

 at least expresses its resemblance to something already 

 known, since by predicating of it a name entirely new 

 we at first convey no information. In this manner 

 the name of a species often becomes the name of a 

 genus; as salt, for example, or oil; the former of which 

 words originally denoted only the muriate of soda, the 

 latter as its etymology indicates, only olive oil; but 

 which now denote large and diversified classes of sub- 

 stances resembling these in some of their qualities, 

 and connote only those common qualities, instead of 

 the whole of the distinctive properties of olive oil and 

 sea salt. The words glass and soap are used by mo- 

 dern chemists in a similar manner, to denote genera 

 of which the substances vulgarly so called are single 

 species*. And it often happens, as in those instances, 

 that the term keeps its special signification in addition 

 to its more general one, and becomes ambiguous, that 

 is, two names instead of one. 



These changes, by which words in ordinary use 



* " The term alkali, in its original sense, signified that parti- 

 cular residuum which was alone obtained by lixiviating the ashes of 

 the plant named kali, but the word is now so generalized, that it 

 denotes any body possessed of a certain number of properties." 

 PARIS'S Pharmacologia, vol. i., p. 68. 



