NEW YORK CITY — Sotheby’s has been retained by The New York Public Library to sell 19 works of art comprising 15 paintings and four busts. Among the works are Asher Durand’s masterpiece “Kindred Spirits” and two Gilbert Stuart portraits of George Washington.

The consignment is expected to bring in the range of $50 million to $75 million.

Durand’s “Kindred Spirits,” painted in 1849, commemorates the friendship of Thomas Cole, America’s first great painter, and William Cullen Bryant, America’s first great poet, by depicting them in a magnificent natural setting.

Bryant delivered a stirring eulogy for Cole when he died suddenly in 1848 and in recognition of this eulogy, “Kindred Spirits” was commissioned by one of Durand’s most important patrons as a surprise gift to Bryant. In the picture, Bryant and Cole stand on a majestic rocky ledge overlooking a breathtaking vista of Catskills scenery. Titled with a phrase that appears in a sonnet by Keats, “Kindred Spirits” captures the shared reverence for nature both men had achieved in their respective artistic spheres.

The painting descended in Bryant’s family, and was given by his daughter, Julia Bryant, to the New York Public Library in 1904.

Of the two portraits by Gilbert Stuart of George Washington, the earlier was painted in 1797 while Washington was serving his second term as President of the United States. The Revolutionary War hero and Chief Executive is depicted half-length, seated, wearing a black velvet suit, holding a document that bears his name and with a sword across his lap.

The portrait was commissioned by William Kerin Constable, a New York City merchant, to present to Washington’s first Secretary of the Treasury, Alexander Hamilton. While many elements of this portrait recall those that appear in the famous “Lansdowne” portrait in the National Portrait Gallery, a seascape in the background of the present work is unique in Stuart’s output. It has been suggested that it may commemorate Hamilton’s support of the Jay Treaty with Great Britain, a timely issue that would have been of crucial importance to a New York merchant and called forth the gift.

The portrait descended in Hamilton’s family and became the property of the New York Public Library upon the consolidation in 1895.

A second portrait of George Washington by Gilbert Stuart, dating from around 1800, is the first of four identical full-length paintings — the other three are in historical societies — and the only one that was painted completely by Gilbert Stuart.

Depicting Washington with his right hand resting on a document on a table, his left hand holding a sword hanging from his waist, the portrait is known as the “Munro-Lenox Portrait” after two Nineteenth Century owners, Peter Jay Munro and James Lenox.

 After Lenox’s death, the library he had established in 1870 merged with the Astor Library and Tilden Trust to become the New York Public Library.

Also among the offerings will be John Singleton Copley’s “Portrait of Francis Deering Atkinson,” painted in 1765 and depicting the elegant Mrs Theodore Atkinson seated at a table playing with a pet squirrel on a chain. The motif of the squirrel had been used by Copley in a portrait of his half-brother Henry Pelham, painted the same year in which won Copley acclaim when it was exhibited at the Society of Artists in London.