Conversation so far:
is slang specific to a particular group
Slang can be either culture-wide or known only within a certain group or subculture.
when was the term slang first used
In its earliest attested use (1756), the word slang referred to the vocabulary of low or disreputable people.

Question: did anything change about the term in the nineteenth century
Self-contained rewrite: did anything change about the term slang or how it was used in the nineteenth century