What was mcelveen purpose for writing this letter

The McElveen's purpose for writing the letter was to inform Oakes that he had bought for him a new slave named Isaac who is a young and brilliant boy and also to tell him about his other affairs in the future.

Explanation:

In the letter written by A. J. McElveen to Ziba Oakes, McElveen speaks particularly about the trade of slaves. He tries to praise the new slave that he has bought for Mr. Oakes for $11. He tells about his upcoming engagements at various places that he's going to participate in for the purpose of getting more slaves for trading.