Oliver Johnson, an anti-slavery lecturer, recently visited this prison, and gives the following account of the adventure in the Anti-Slavery Standard. On going to the slave prison, and inquiring for the owner, Hope H. Slatter, I learned that he was absent; but a man who represented himself as his brother and partner, and who told me that he resided at New Orleans, and was employed in effecting the sale of the human chattles purchased at the North, readily granted me permission to enter and examine the premises. The prison is situation on one of the most public streets of the city, and in the rear of the dwelling and office of the owner. A simple sign, on which was inscribed the well known name of the dealer in human flesh, hung over the office door. - There was nothing upon it, however, to indicate the horrid business in which he was engaged - a business in which, it seems almost incredible to suppose, any man could follow, who had not 'rocked conscience asleep,' and arrived at a state where, 'At last, extinct each social feeling, fell And joyless inhumanity prevades And petrifies the heart.' And yet I am told that Mr. Slatter is a man of so much natural amiability, in the ordinary intercourse of life, that no one would suspect him of being engaged in an occupation which sunders the holiest ties of our nature, and tramples all inalienable rights in the dust! How such apparent contradictions are to be reconciled, is more than I can tell. Some times I am tempted to declare, that the amiability of such men is nothing more than 'well trimmed hypocricy;' but when I consider the facility with which man, when he once enters on a criminal course, 'Puts out the eye of reason- prisons, tortures, binds, And makes her thus, by violence and force, Give wicked evidence against herself-' I am half inclined to take back the assertion, and to conclude that they have by some strange, and, to me, unnaccountable process, 'conquered a peace' with there consciences. By emotions on entering the mart of slaves and souls of men I will not attempt to describe. Here I saw nearly a hundred human beings, of all ages and both sexes, locked up like so many wild beasts, and awaiting purchasers- Many flocked around me as I entered, evidently supposing that I had come to look at the assortment, and to make choice of such as I wanted to buy. I at once undeceived them, by telling them that I was an abolitionist; that I abhorred slavery as one of the worst of crimes; and that I had been laboring, to the extent of my ability, for several years to procure their emancipation. I told them also that thousands of people in the northern States had associated together for the purpose of breaking their chains; and begged them to remember, for their consolation under the sore trials they were called to suffer, that although the day of emancipation might not come in their time, some of their children would surely live to see it. I told them that they might rest assured, that those who had undertaken their cause would never turn back, but would persevere until victory crowned their exertions; and I begged of them to convey this information to their companions in tribulation, wherever their lot might be cast. They listened to me with an eagerness which showed how deeply they were interested in what I said; and the hearty 'God bless you,' which some of them uttered while tears of gratitude filled their eyes, was more than enough to compensate me for all my labors in their behalf. The pleasure I felt in communicating to them these 'glad tiding' was indescribable. Among the group were several mothers, which infants in their arms, who told me, with deep emotion, that they had been sold away from husbands and children whom they never expected to see again in this world. Among the females were two whose complexion was so near white as to attract peculiar attention. They told me that they were sisters, and the children of their master! Some time before they were sold, they ran away from Frederick, and reached Philadelphia in safety. Here they took lodgings with a colored family, and I believe they told me they did not communicate the fact that they were slaves, for fear of being betrayed. By some means the master found out the place of their retreat, and recovered them by stratagem. A company of white men went to the house with a carriage, one of the pretending that the girls were his sisters, and that he had been sent to convey them home! The ruffians seized them, thrust them into the carriage, and then drove all speed to Wilmington, I believe, where they were put on board the cars and carried to Baltimore. For the crime of running away, they were sold by their own father, for the New Orleans market! The substance of their story, I understand, has been published in the Pennsylvania Freemen, though I have never read it. Perhaps my account may not be accurate in every particular, as I was interrupted before I had done conversing with them. Their tale was enough to harrow up every soul not absolutely petrified by participation in 'crimes of the blackest hue.' While I was conversing with these girls and taking notes of their story, the colored gate-keeper of the establishment became alarmed, and informed the brother of Mr. Slatter what I was doing. In consequence of this, the latter come to the gate, and sent for me to come out. Of course I obeyed his orders; and as I passed out, he said, in a passion, 'D--n you, you've been taking notes; you've abused my confidence; when I let you in, I supposed you to be a gentleman, d--n you.' I told him I was not aware that he had any objection to a visiter's taking notes of whatever he found to interest him; and frankly informed him that I had made some memoranda of the story of the two girls from Frederick. He said that such a course was not allowable, and appeared to be quite angry with me. When I ventured to inquire how he could reconcile his conscience to his business, he assured me, as he laid his hand on his breast, that he was a very conscientious man! that although he was not a professor of religion himself, he had as much respect for christianity, as any other man, he would be d----d if he hadn't! 'Slavery.' said he, in according to christianity, and justified by the ablest divines in this country, at the North as well as the South. I treat my niggers in the kindest manner. When they arrive at the South, I give them pleasant homes; and every one is furnished with a good bed, and a net to keep off the musquetoes! Why d--n it, there is not a happier set of laborers on God's earth than the niggers of the South,' &c. &c. I retired with a firmer resolution than ever to wage a war of extermination against the nefarious and bloody system, and with a mind filled with abhorrence on account of such wickedness. If I had needed any thing to impress indelibly upon my mind, a sense of the injustice of slavery, and to make the principles of abolition a part of my nature, the scenes I witnessed in this slave prision would have been sufficient.