A dialogue concerning the slavery of the Africans; shewing it to be the duty and interest of the American states to emancipate all their African slaves. : With an address to the owners of such slaves. : Dedicated to the Honourable the Continental Congress. : To which is prefixed, the institution of the society, in New-York, for promoting the manumission of slaves, and protecting such of them as have been, or may be, liberated. : [Four lines of Scripture texts]