Short answers, pulled from the story.
Manumission, also called enfranchisement, is the act of freeing enslaved people by their owners. Historian Verene Shepherd defines the most widely used form as gratuitous manumission: the conferment of freedom on the enslaved by enslavers before the formal end of the slave system.
In ancient Rome, a freed slave became a libertus and a citizen, taking the former owner's family name. The formal ceremony called manumissio vindicta involved a magistrate's lictor laying a rod on the slave's head while declaring the person free. Manumissions were subject to a state tax, and the lex Fufia Caninia of 2 BC capped how many slaves could be freed in a will.
Reytory Angola was a freed slave who in 1661 became the first Black person to individually petition a legislature in North America. She petitioned for the manumission of her enslaved adopted son in New Amsterdam.
After the cotton gin was invented in 1793, manumissions declined sharply because the new machine enabled vast new areas of cotton cultivation, driving up demand for enslaved labour. Most Southern states eventually made manumission legally near-impossible, with Florida prohibiting it outright.
In colonial Peru, enslaved children could be freed at the moment of baptism, but these freedoms often came with conditions requiring years of continued servitude. Female slave owners were more likely than male owners to use baptism for manumission, and often used language of personal affection in the written records. Children freed at baptism while their parents remained enslaved were far more likely to be re-enslaved.
The Law of February 1794, passed by the French First Republic's National Convention, abolished slavery throughout the French colonial empire. An earlier edict of the 3rd of July 1315 by King Louis X had abolished serfdom in the French royal domain and established the principle that the soil of France frees the slave who touches it.