Answer
The principal is bound by the acts of the agent done within the scope of the agent's authority (Article 1910). Even where the agent exceeds his authority, the principal may still be bound under the doctrine of ratification, where he expressly or impliedly adopts the act, or under apparent authority (agency by estoppel), where the principal's own conduct led a third person to reasonably believe the agent was authorized. A principal who revokes an agency but fails to notify third persons may remain bound to those who, in good faith, continued to deal with the agent.
Agency is extinguished by the modes listed in Article 1919 — among them revocation by the principal, withdrawal by the agent, the death, civil interdiction, insanity, or insolvency of the principal or the agent, the dissolution of the firm or corporation that entrusted or accepted the agency, the accomplishment of the object of the agency, and the expiration of its term. An agency coupled with an interest, however, cannot be revoked at the principal's sole will and survives his death.