Today, being Friday, we'll focus on the Litany of the Most Sacred Heart of Jesus. Like the Litany of St. Joseph, it was only approved for public prayer relatively late, in this case by Pope Leo XIII in 1899. This Litany is actually a composite of other litanies, primarily from the 17th century (please see the link above for more information). While virtually all litanies were forbidden from public use in 1601 (that of All Saints and of Loreto being exceptions), there was a slight loosening of this prohibition in the 19th century, during which the other approved Litanies received their approbation.
In structure, it is much like the other litanies which we have seen: the Kyrie, invocation of the three members of the Trinity to have mercy on us (first individually, then as a unity), the come petitions to the Heart of Jesus to have mercy upon us, followed by the invocations of the Agnus Dei. One of the notable features is that the series of petitions to the Heart of Jesus are 33 in number, reflecting the number of years which Jesus is said to have lived on earth.
Like other devotions to the Sacred Heart of Jesus (for instance the Little Office of the Sacred Heart, mentioned in an earlier post), it seems best suited for Fridays, especially the First Fridays of the month and the Solemnity of the Sacred Heart of Jesus (third Friday after Pentecost). Additionally, it is well suited to every day during the month of June, which is typically held in honor of the Sacred Heart of Jesus, and is the month in which the Solemnity of the Sacred Heart of Jesus usually falls. Like the other approved litanies, it is enriched with a partial indulgence