Henry Cros was known as both a sculptor and a writer. He was the elder brother of the eccentric poet and inventor Charles Cros (1842–88) and he received a traditional training under the painter Jules-Emmanuel Valadon (1826–1900) and under the sculptors Francois Jouffroy and Antoine Etex. He first exhibited at the Salon of 1861 in Paris, showing a plaster bust of his brother (untraced), and in 1863 he participated in the Salon des Refuses.
In the early part of his career, Henri Cros made highly refined wax sculptures. The wax was bulk dyed then painted and decorated with beads. Cros's inspiration came from small wax reliefs and painted portraits from the Renaissance period.
Between 1869 and 1880 he researched techniques of making sculpture in polychromed wax. At the Salon of 1873 he exhibited the Prize of the Tournament (Paris, Mus. d’Orsay), a polychromed wax relief studded with pearls, which was purchased for the State. It depicts a stylized group of medieval women in court costumes occupying a box at a tournament. He produced 12 works in this medium, and although few have survived, they served as technical prototypes for the work of other sculptors, notably Degas and Désiré Ringel d’Illzach. His investigations into the way wax had been used in earlier art culminated in a study, undertaken in collaboration with the scientist Charles Henry, of the use of encaustic in the ancient world. From the mid-1880s Cros became interested in another ancient technique, that of making polychrome sculpture from fired glasspaste imbued with metal oxides. He sought State sponsorship for his research and was rewarded in 1891 by being provided with a studio at the Sèvres Porcelain Factory, for the production of pâte de verre sculpture and decorative work. His most substantial surviving pieces in this medium are the History of Water (1892–4; Paris, Mus. d’Orsay), a relief for a fountain, and the History of Fire (1894–1900; Paris, Mus. A. Déc.), a lunette relief. Unlike the medievalism of his wax pieces, these display a painterly classicism and a free, Symbolist approach to mythological themes. His use of decorative media to break down the boundaries between painting and sculpture is symptomatic of a wider endeavour throughout Europe at the end of the 19th century to unite the fine and the applied arts.

References : Musee d'Orsay Paris
Grove Art excerpts Oxford Art Online