4th. _Runaways._--Of the proportion of the slaves that run away, to those that do not, and of the proportion of the runaways that are _taken_ to those that escape entirely, it would be difficult to make a probable estimate. Something, however, can be done towards such an estimate. We have before us, in the Grand Gulf (Miss.) Advertiser, for August 2, 1838, a list of runaways that were then in the jails of the two counties of Adams and Warren, in that State; the names, ages, &c. of each one given; and their owners are called upon to take them away. The number of runaways thus taken up and committed in these _two_ counties is FORTY-SIX. The whole number of _counties_ in Mississippi is _fifty-six._ Many of them, however, are thinly populated. Now, without making this the basis of our estimate for the whole slave population in all the state--which would doubtless make the number much too large--we are sure no one who has any knowledge of facts as they are in the south, will charge upon us an over-statement when we say, that of the present generation of slaves, probably _one in thirty_ is of that class--i.e., has at some time, perhaps often, runaway and been retaken; on that supposition the whole number would be not far from NINETY THOUSAND. 5th. _Hired Slaves._--It is impossible to estimate with accuracy the proportion which the hired slaves bear to the whole number. That it is very large all who have resided at the south, or traveled there, with their eyes open, well know. Some of the largest slaveholders in the country, instead of purchasing plantations and working their slaves themselves, hire them out to others. This practice is very common. Rev. Horace Moulton, a minister of the Methodist Episcopal church in Marlborough, Mass., who lived some years in Georgia, says: "A _large proportion_ of the slave are owned by masters who keep them on purpose to hire out." Large numbers of slaves, especially in Mississippi, Louisiana, Arkansas, Alabama, and Florida, are owned by _non-residents_; thousands of them by northern capitalists, who _hire them out_. These capitalists in many cases own large plantations, which are often leased for a term of years with a 'stock' of slaves sufficient to work them. Multitudes of slaves 'belonging' to _heirs_, are hired out by their guardians till such heirs become of age, or by the executors or trustees of persons deceased. That the reader may form some idea of the large number of slaves that are hired out, we insert below a few advertisements, as a specimen of hundreds in the newspapers of the slave states. From the "Pensacola Gazette," May 27. "NOTICE TO SLAVEHOLDERS. Wanted upon my contract, on the Alabama, Florida, and Georgia Rail Road, FOUR HUNDRED BLACK LABORERS, _for which_ a liberal price will be paid. R. LORING, _Contractor_." The same paper has the following, signed by an officer of the United States.