This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
The Florist and Pomologist says: " The sweet violets are among the most charming little gems of the spring garden, and they will grow almost anywhere, provided they get pure air; but what they most delight in is a rich, deep, loam soil, with liberal soakings of manure water during the flowering season. The following are a few of the most distinct: King of Violets, an improvement on arborea, dark violet, a good grower, free bloomer, and fit for green-house or out-door culture. Heine des Violettes, blush-white, very double and hardy, a free bloomer; will do either in-door or out. The Giant and Czar, if not the same, are very much alike; both have large flowers, with long stalks; which make them very valuable for either bouquets or vases. Rubra-plena, double red or copper color, very distinct, hardy and a free bloomer. Arborea alba, tree habit, pure white, one of the best for in-door cultivation, as it likes a little protection. Devoniensis, in bloom the whole season, and has a long flower stalk, which makes it valuable for gathering; is of a light violet color. Neapolitan, one of the most beautiful, second to none, remarkably sweet-scented, with charming pale-blue flowers.
These are all worthy of general cultivation".