This novel... will create a sensation, both for the ability with which it is written, as well as the interest of the subject, and will be universally read and admired. It was written expressly for the New World, by one of the best novelists in this country... The incidents of the plot are wrought out with great effect, and the excellence of its moral, and the beneficial influence it will have, should [give] this Tale the widest possible circulation.
The ad was certainly misleading; Whitman was hardly "one of the best novelists in the country." Further, the most unusual aspect of Franklin Evans is that it is a temperance novel, part of a long tradition of popular literature that discouraged the use of alcohol. In fact, it was not Whitman's first temperance writing (an earlier example was his story "Reuben's Last Wish"). The title character falls in with the "wrong sort" and starts visiting bars and whorehouses. Even so, he marries a good woman, though he drives her to an early grave because of his overuse of alcohol. Evans moves south, where he marries a former slave. He falls in love, however, with another woman — and she is killed by his wife.
Whitman's temperance novel is different from others, including the famous Ten Nights in a Bar-Room by Timothy Shay Arthur, in that bad things happen even when the alcoholic character is sober. This effectively implies that inebriation is so destructive that there is no hope for reform once it becomes a habit. Franklin Evans had a circulation of at least 20,000 copies (compare to 800 copies of the first edition of Leaves of Grass in 1855).
Some four decades after the publication of Franklin Evans, Whitman laughed it off as something he never believed. He called the book a "damned rot — rot of the worst sort." Though he once claimed he never drank alcohol until he was 30, he joked that Franklin Evans was written in three days — while he had been drinking.
*A particularly good section on Franklin Evans, the cultural context of the temperance movement and Whitman's later denial of it, is found in Jerome Loving's Walt Whitman: The Song of Himself (1999).