nig vs welsh

nig

verb
  • to behave as a stereotypical black person 

noun
  • nigger 

welsh

verb
  • To cheat or swindle someone, often by not paying a debt, especially a gambling debt. 

  • To go back on one's word. 

How often have the words nig and welsh occurred in a corpus of books? (source: Google Ngram Viewer )