Two watercolors that art collector Dr. Alfred Barnes bought 90 years ago for $100 have yielded an unexpected surprise.

Conservtors at the Barnes Foundation in Philadelphia recently removed the frames from the watercolors depicting the landscape of southern France. On the reverse side two unfinished sketches--one graphite and the other watercolor--were discovered. 

Museum officials say the sketches have likely not been seen since the early 20th century.

'We've had (the watercolors) out of the frame before. But the backs were covered with brown paper,' said Barbara Buckley, the foundation's senior director of conservation and chief painting conservator, to The Philadelphia Inquirer. 

'That's one of the reasons they were sent (for conservation). Brown paper is very acidic, and they needed acid-free paper.'

“Barnes bought The Chaine de l'Etoile Mountains (BF650) and Trees (BF655) from Leo Stein, the American collector who, along with his sister, Gertrude, had assembled one of the world’s most important collections of modern European art,” said Martha Lucy, Assistant Professor at Drexel University and Consulting Curator at the Barnes Foundation. “What Barnes probably didn’t know was that in purchasing these two watercolors from Stein, he had actually acquired four works by Cézanne.”