In presenting the circular, which will be found in another column, of which a committee of colored persons have undertaken the distribution, (and which was written by one of themselves,) it gives us pleasure to commend it as the evidence of a new and generally unexpected change of sentiment on the part of the colored population, or, at least, some portion of it. It is well known that for twenty-five years the Colonization Societies in this country have labored to present before that portion of our population, the advantages which must accrue to them, from emigration to a land where they might enjoy, undisturbed, those social and material privileges which it was impossible ever to expect they could obtain by a residence of centuries in this country, and that these appeals have met with comparatively little attention, and, in deed have been received with very bad grace by the great mass of those whom it was intended to benefit. The cause of this opposition was to be found in the steady and violent animosity of those white fanatics, who, setting themselves up as the peculiar friends of the blacks, represented that the prejudice against their color was merely an arbitrary sentiment, which time would weaken or entirely dissipate; and that they might still look forward to enjoying, in this country, an equality in social and political rights with the whites. This assumption of peculiar friendliness on the part of the Abolitionists, and the plausible reasonings with which they approached their "colored friends," have acquired the confidence of the latter, who are now, however, beginning to awake to a just idea of their condition and future prospects in this country. They have discovered that the loud-mouthed protestations of the Abolitionists, are the mere effervescence of an intermeddling and dangerous faction, against whose principles the whole Union--whose destruction they have meditated--has pronounced in tones of thunder; a faction whose baleful alliance is shunned most religiously, by both of the great parties of the country. They have discovered that underground railroads are a device to inveigle the slaves from a condition of comparative comfort, into the _freedom of starvation_, with a poor display of political privileges, which are mockery in view of their exercise by an ignorant and despised minority; that the expectations fostered in behalf of the free blacks are proved to be entirely futile by the continued attitude of opposition held towards them, when there is a question of lessening the social and political gulf which divides the races. They discover that the rapid immigration of whites from every quarter, is encroaching upon their employments, and lessening their chance of gaining a thrifty livelihood, even in those menial pursuits to which they are chiefly limited.