This piece is is in the Art Nouveau style that was all the rage from the 1890's through to World War One (1914). Busts of this type produced in France and Austria during this period were made in pottery, porcelain, bronze and “Spelter”. The upper range pieces in genuine bronze tend to be well marked and carry the stamp of the foundry that cast it. This one is a late Art Nouveau piece, signed "H Jacobs" and stamped "Copyright 1914 Napoleon Alliot" appears to be bronze, but looks can be deceiving.
Some of the more mass market examples like this one were not actually bronze at all, they were cast “Spelter”, a zinc alloy that is given a very convincing bronze patina. Most like this one date from the turn of the 19th through the early 20th. The original designer of this piece was a Belgian Sculptor/Architect named Henri Jacobs (1864-1935) . In the current market a Spelter bust like this by Jacobs could sell at auction for close to $2000.00, with smaller examples in the $400.00- $600.00 range.