[From the Chicago Tribune.] Tho chilliug northershave swept over the malarial rcgions of the South, and purifted the utmosphore. Jack Frost, who in our Northern clime disports himsolf in ponciliiig window-pietures, hns luid more serious work in the yalley of death, and at last has triumphed in bis conflict with the yellow monster. There are yet sufforers who will linger along and die, but tiie spread of the pestilence is stopped ; and thosë who have tlms fur escaped can breatbe more freely at the blessed assurance of safety brougbt by the crost, and thoso who fled from their homes can now return, for thé dangev is over. The good news lias spread fastej than the fever, and from every part of the country the refugees are hurrying home to their friends. Life is taking the place of death all through the Mississippi valley. The sileiit cities are waking up. The deserted fields and plantations are once more fllling with laborers. The baryesi will be gathered. The wheels of business once more begin to revolví, nftor their long vest, and the tidc of trade resumes its flow through its aceustomed ehannels. The horrible reality of fever will soon be only a memory, bitter in its associations to many pooi souls, dark as it stretches to the graveyard where so many thousands have gone to their rest, but blessed and illuininated with the beneficcnce of charity and sympathy that rlowod in upan them when everything else wa.s darle. Now that the worst is over and the limita are defined beyond which the pestilence cannot go, it is possible to roughly estímate the full extent of the disaster it bas oaused. On the 24th of July last a brief dispatch from New Orleans said : " 33he Picayune. publishes a statement that fourteen cases of yellow fever have occurred, seven fatal. Tlie Board of Health hopes to check the spread of the disease." On the nest 3ay Ur. Ghoppin, who afterward saerinced his life in his seivice for humanity, officially announced its presence in New Orleans to Surgeon General Woodworth, of the Marine Hospital service. In the three months whioh have elapsed siuce tbe Boai'd of Health hoped to check its spread that littlo cloud of fever, " no bigger tLan a man's hand," has extended over portions of seven States, finding its extreme northern limit at Cairo, and embracing an area at least 150 miles wide along the eastern bank of tho Mississippi river, with exceptional cases in portions of Texas and Arkansas. In these three months fully 100,000 persons have been attacked by the pestilence, and at least 20,000 have died, and more are to follow who took the diseaso before the advent of frost. As a rule, about one in four cases has boen fatal, showing that the fever bas been us destructive to life as a battle, where the same proportiou of fátality to thoso struck usually prevails. It is almost impossible to estímate the material losses, but they will embrace millions upoii millions of dollars, caused by the stoppage of trude, the paralysis of commerce, the deprivation of likbor, and tho waste in ungathered hai-vests. It bas been a fearful blow to the South, not only in tbe thousands of homes that have been desolated, in the losses oí skillful and philanthropie men,aud in the comparativo depopulation of sniall interior towns, but in the sudden stoj)page of labor and business just at the time when the South was beginning to recover from the distress of war and panic and needed every man's work.