Final answer:
The specific slave owner who freed Isabel and Ruth upon her death is not named in the provided information. This act of freeing slaves posthumously through a will was a practice some slave owners followed and could be contested by heirs or state laws.
Step-by-step explanation:
The slave owner who specified in her will that Isabel and Ruth should be freed upon her death is not directly named in the information provided. However, it is a historical fact that during the period of American slavery, it was not uncommon for slave owners to free their slaves upon the owner's death through provisions in their wills. This practice could be a reflection of their change of heart, the close personal relationships they might have had with certain slaves, or their beliefs about slavery at the end of their lives. Such acts sometimes resulted in court battles when other heirs contested the wills or when the laws of the state interfered with the act of manumission.
When discussing the broader context of slavery, many former slaves recounted the severe treatment and family separations they endured, which is evident from the excerpts taken from LibreTexts™. The details highlighted provide a glimpse into the lives of slaves and the difficulties they faced, but they do not conclusively determine the identity of the specific slave owner in question.