Ad Dig. 12,6,53ROHGE, Bd. 22 (1878), Nr. 66, S. 299: Cond. possessionis gegen den aus Irrthum Besitzenden. Besitz ein Vermögensobject.Proculus, Epistles, Book VII. A master gave his slave freedom by his will, on condition of his paying ten aurei, and the slave, not knowing that the will was void, paid me the ten aurei; the question arises, who has a right of action to recover the money? Proculus answered that if the slave paid the money out of his peculium, when permission to do so had not been granted him by his master, the money remains the property of his master, and he can bring suit for the recovery of the same by an action in rem. But where another party, at the request of the slave paid me his own money, it becomes mine, and the owner of the slave on whose account it was paid can bring an action for its recovery; but a more indulgent, as well as a more practical method would be for the party who paid the money to himself recover what belongs to him directly from me.

Ad Dig. 23,3,67Windscheid: Lehrbuch des Pandektenrechts, 7. Aufl. 1891, Bd. II, § 422, Note 4.Proculus, Epistles, Book VII. Proculus to his grandson, Greeting. Where a female slave marries, and gives her husband money, as dowry, whether she knows that she is a slave or not, she cannot make her husband the owner of said money, and it will still remain the property of the person to whom it belonged before it was given as dowry to her husband, unless he should have obtained it by usucaption. And not even after the woman has become free, while living with the same man, will she be able to change the condition of this money. Hence, not even after a divorce has taken place, can she legally bring an action based on her right of dowry, or a personal action to recover the money, but the party to whom it belongs can legally sue for it. But if the husband has obtained a right to said money through usucaption after having had it in his possession, of course because he thought that the woman was free, I am confirmed in my belief that he has profited by the transaction, provided he obtained the right to the money by usucaption, before the marriage. I am of the same opinion where he obtained anything by means of said money before it became the dowry, provided he was not in possession of it, and was not guilty of fraud to avoid being in possession.

Proculus, Epistles, Book VII. You brought an action De peculia against a master for a debt of his slave, and it was held that the sureties were not released. If the same slave who had been entrusted with the management of his peculium should pay the money, you have read correctly that the securities will be released.