"REMOVAL.--Blakey & McAfee have removed to No. 93, Olive-street, six doors west of their old stand. They are prepared at all times to pay the highest prices for negroes. _They have also a good secure yard, with a strong jail attached_, and are prepared to board negroes sent to this market for sale. Persons having negroes for sale will please call and see us. Those wishing to purchase can find what they want at our yard. BLAKEY & MCAFEE, No. 93, Olive-street." Hon. Horace Mann has described to us the slave-pen in the city of Washington; and another member of Congress informs us, that the United States jail in the District of Columbia is frequently used for the purpose of storing human beings for sale! Thus, in the "National Intelligencer" (Dec. 19, 1844), we find the following notice:-- "FOR SALE,--A likely young negro, in the jail of Washington. He is a most excellent teamster, and well acquainted with the care of horses. Persons wishing to purchase will apply to Mr. Ball, at the jail, where the boy may be seen, and further information given." The activity of this trade may be inferred from these advertisements, which constitute but a small portion of what might be produced. In the "National Intelligencer," March 28, 1836, three slave-traders in the District of Columbia advertise for _twelve hundred_ negroes, and a fourth offers to buy any number! Here is one of the advertisements:-- "CASH FOR FIVE HUNDRED NEGROES, including both sexes, from ten to twenty-five years of age.--Persons having likely servants to dispose of will find it their interest to give us a call, as we will give higher prices in cash than any other purchaser who is now or may hereafter come into the market. FRANKLIN & AMFIELD, Alexandria." In a later number of the same paper are the following:-- "CASH FOR NEGROES.--I will give cash and liberal prices for any number of young and likely negroes, from eight to forty years of age. Persons having negroes to dispose of will find it to their advantage to give me a call at my residence, on the corner of Seventh-street and Maryland Avenue, and opposite Mr. Williams's private jail. WILLIAM H. RICHARDS." "CASH FOR NEGROES.--The subscriber wishes to purchase a number of negroes for the Louisiana and Mississippi market. Himself or an agent at all times can be found at his jail, on Seventh-street. WM. H. WILLIAMS." In a later number, June 24, 1843, Mr. Richards is not so eager:--