Who does Tituba accuse of being a witch in the first act?
Tituba is in a truly pitiable situation: accused of witchcraft by Abigail, she is threatened with death by both her master, the Reverend Parris, as well as Mr. Thomas Putnam. However, Mr. Hale is kind to her, and gentle; he asks, "You would be a good Christian woman, would you not, Tituba? [....] And you love these little children?" He gives her an opportunity to speak for herself, and he doesn't threaten her with pain or death ever. He asks her questions gently, and he believes her answers.
Then, "Hale takes her hand. She is surprised." Tituba is shocked to be treated kindly because she is so unused to it. Hale says that they will bless Tituba, that she is "God's instrument put in [their] hands to discover the Devil's agents among [them]." He tells her that she is special and that she has a holy purpose, not that he will beat her or hang her as the others have. Tituba seems to want to please Hale, to give him the information he desires: and so she names Goodwife Good and Goodwife Osburn as witches that she has seen with the Devil. Once she does so, however, Abigail seems to realize the great power that is conferred on those who accuse others (after all, she accused Tituba and was believed, and now Tituba has accused two others and is believed), and she begins to make further accusations herself (along with her cousin, Betty).
In Act One, Abigail Williams claims that Tituba was able to conjure Ruth Putnam's dead sisters. Shortly after, Tituba admits to speaking with the Devil after being threatened by Reverend Parris and Mr. Putnam. Tituba then tells Reverend Hale that she believes that somebody else has bewitched the children. Mr. Putnam then suggests to Tituba that Sarah Good and Sarah Osburn were working with the Devil. This is significant because it provides Tituba with two people to cast the blame. Sarah Good and Goody Osburn both have terrible reputations throughout Salem and are viewed with contempt by the community members. Tituba, sensing the dangerous situation she is in, accuses both Sarah Good and Goody Osburn of witchcraft. Sarah Good is a mentally unstable homeless woman, and the two women are both considered easy targets.
Tituba is led to accuse Goody Good and Sarah Osburn. She tells Parris and Hale that she had had dealings with the devil: "...And then he come one stormy night to me and he say, "Look! I have *white* people belong to me." And I look -- and there was Goody Good...And Goody Osburn."