Is it the duty of American slaveholders to liberate their slaves? I feel no hesitancy in replying to this interrogatory. It would be their duty, as Christians, to liberate their slaves, provided the condition of the slave would be improved thereby; otherwise it is their duty to retain them in bondage, and make that provision for them which their circumstances require. They should make ample provision for their physical wants--enlighten their minds; and so far as is practicable under existing circumstances, they should elevate their characters above that debasement and degradation, in which, ignorance, prejudice and vice has involved them. It is clearly the duty of slaveholders to place their slaves in that condition, which will conduce most to their happiness here and hereafter. But if this is their object, they could not, as a general rule, take a worse step, than to liberate them in their present condition and turn them loose among us. Nor do I consider the mass of the negro population in this country as yet prepared for colonization: but I would rejoice to see all well-disposed and intelligent negroes manumitted and colonized. The poverty, vice and degradation of free negroes is notorious, throughout the length and breadth of this country--North and South; but having so frequently alluded to it, I deem it unnecessary to say more on the subject. I will however remark, that if the entire African population were manumitted and turned loose among us; they would be forced to subsist almost entirely by theft, and all the county jails and state prisons in the Union, would not contain one in a hundred of the convicts. The fact is, such would be their depredations on the white population, that the whites would shoot them down with as little ceremony as they now shoot a mad dog; and their ultimate extermination would be the inevitable consequence! I appeal to facts. It was stated a few years ago by an able writer; that in Massachusetts the free negroes were 1 to 74, viz., there were 74 white persons for every free negro in the State; and yet one-sixth of all the convicts were free negroes. That in Connecticut the free negroes were 1 to 34; and that one-third of the convicts were free negroes. That in New York the free negroes were 1 to 35; but that one-fourth of the convicts were free negroes. That in New Jersey the free negroes were 1 to 13; negro convicts one-third. That in Pennsylvania the free negroes were 1 to 34, and that one-third of the convicts were free negroes. He moreover stated, that one-fourth of the whole expense connected with the prison system of the entire North was incurred by crime committed by free negroes; and that the same was true with regard to the pauper expenditures of the entire North. In view of these facts, we can feel but little surprise, that Indiana and Illinois have enacted laws to interdict the immigration of free negroes into those States.