From 1836 to 1839, the American Anti-Slavery Society published The Slave's Friend, a juvenile periodical edited by abolitionist Lewis Tappan. Each issue, specially sized to fit small hands, was 16 pages in length and featured a mix of stories, news items, and poems meant to gently but firmly tell white children about the evils of slavery. The New York Public Library's digital collection offers a small collection of scans of the magazine's 1837 issues.
Because the American Anti-Slavery Society favored complete and immediate emancipation, writes historian Christopher D. Geist, The Slave's Friend was sometimes shockingly blunt in its depiction of slaveholding. "A frequent theme of The Slave's Friend was the total cruelty of the slaveholders," writes Geist. The magazine's stories told of slaveholders who cropped enslaved people's ears and chained them in attics or lashed them for the smallest of offenses.
Many pages of The Slave's Friend equated cruelty to animals—imprisonment, physical torment—with enslavement of people, suggesting that Christian sympathy, when properly felt, would lead a person to be humane to both animals and the enslaved. This kind of imagery, writes historian Spencer D.C. Keralis, "is ubiquitous in abolitionist writing in general, but particularly prevalent in texts marketed to children."
Issues of The Slave's Friend were included in the society's mailings of abolitionist publications to Southern states. In 1835, the magazine's third issue reached the post office in Charleston, South Carolina, along with other abolitionist literature for adults. Pro-slavery citizens seized and burned the delivery, immolating The Slave's Friend along with its more mature cousins.
Unfortunately, the NYPL's collection of The Slave's Friend pages is somewhat random—the library didn't digitize full issues, and the metadata for each page doesn't note which issue it came from. (I think this may be because the pages were initially scanned and published as part of a Web exhibit.) But Swarthmore College has digitized all of the 1836 issues it holds in its library, and you can read them here. Also, historian of children's literature Pat Pflieger has transcribed a full issue from 1835; you can read that here.
Thanks to historian Adam Rothman, who shared a link to the NYPL's Slave's Friend collection on Twitter.