The Song of Los, composed in 1795, was color-printed rather than watercolored later. This technique was more efficient and subject to less variation, but it produced thicker, denser areas of color than when watercolor was added later. The Trianon Press facsimile was made from copy B. It was purchased for Union College by the Friends of the Library.
This work has a complex publication history. Songs of Innocence was composed in 1789 and Songs of Experience in 1794, after which the two were often combined, sometimes with an additional, unified title page. The order of poems within the combined publication varies considerably, as does the number of poems selected for it (and for later reproductions). Thus not all of the poems in the series are included in all versions. The coloration also varies from copy to copy. The 1955 version by the Trianon Press was made from copy Z. Union College holds two copies of this facsimile, which were donated by Hans Rozendaal and Walter Tower.