is now appropriated to a particular species: in the same manner, _Bark_, which is a general term, is applied to express _one_ genus, and by way of eminence, it has the article, _The_, prefixed, as _The_ Bark: the same observation will apply to the word _Opium_, which in its primitive sense signifies _any_ juice (οπος _Succus_) while it now only denotes _one_ species, viz. that of the Poppy. So again, _Elaterium_ was used by Hippocrates, to signify various internal applications, especially purgatives of a violent and drastic nature (from the word ‘Ελαυνω,’ _agito_, _moveo_, _stimulo_), but by succeeding authors it was _exclusively_ applied to denote the active matter which subsides from the juice of the _wild cucumber_. The word _Fecula_, again, originally meant to imply _any_ substance which was derived by spontaneous subsidence from a liquid, (from _fæx_, the grounds or settlement of _any_ liquor); afterwards it was applied to _Starch_, which is deposited in this manner by agitating the flour of wheat in water; and lastly, it has been applied to a peculiar vegetable principle, which like _starch_[80] is insoluble in cold, but completely soluble in boiling water, with which it forms a gelatinous solution; this indefinite meaning of the word _fecula_ has created numerous mistakes in pharmaceutic chemistry; Elaterium, for instance, is said to be a _fecula_, and in the original sense of the word it is properly so called, inasmuch as it is procured from a vegetable juice by spontaneous subsidence, but in the limited and modern acceptation of the term, it conveys an erroneous idea; for instead of the active principle of the juice residing in _fecula_, it is a peculiar proximate principle, _sui generis_, to which I have ventured to bestow the name of _Elatin_. For the same reason, much doubt and obscurity involve the meaning of the word _Extract_, because it is applied _generally_ to any substance obtained by the evaporation of a vegetable solution, and _specifically_ to a peculiar proximate principle, possessed of certain characters, by which it is distinguished from every other elementary body—See _Extracta_. On the other hand, we find that many words which were originally only used to denote particular substances, have, at length, become subservient to the expression of General Characters; thus the term _Alkali_, in its originally sense, signified that particular 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 definite properties.