William Weightman I (September 30, 1813 – August 25, 1904) was a chemical manufacturer and one of the largest landowners in the United States.
Weightman was born on September 30, 1813 in Waltham, Lincolnshire, England. He immigrated to the United States at the age of 16 in 1829 invited by his uncle, chemist John Farr. Farr had founded the firm Farr and Kunzi, the first manufacturers of sulfate of quinine in the United States. Upon Kunzi's retirement in 1836, Farr partnered with Thomas Powers and 27-year-old Weightman to establish Farr, Powers and Weightman, manufacturing chemists. In 1841, Weightman married Louisa Stillwagon; together, they had three children: John, William Jr., and Anne.
When John Farr died in 1847, Weightman became an administrator and executive of the business, which was renamed Powers and Weightman, chemical manufacturers. It profited from quinine sales during the Civil War through a quasi monopoly. In 1875, Powers and Weightman won the Elliott Cresson Medal for Engineering, presented by the Franklin Institute.
Weightman amassed a large fortune through shrewd investments, derived from his manufacturing enterprise, estimated at $51.8 billion in 2014 adjusted value. He purchased hundreds of acres of farms in what is now North Philadelphia and built whole neighborhoods of middle-class housing, serviced by streetcar lines. His architect for these was Willis G. Hale, the husband of one of his nieces.
Having outlived his two physician sons, Farr and William, Weightman came to rely on his daughter, Anne Weightman Walker, in 1903, after her husband died and when she was admitted as a partner. Anne "was the only woman in the United States to hold such a position of responsible trust". They lived in a large mansion, Ravenhill also built by Hale, in the East Falls , Germantown section of the city. At his death in 1904, Ravenill passed on to Anne who gave the estate to the Archdiocese of Philadelphia in 1910. Cardinal Dennis Joseph Dougherty of the Archdiocese granted the Mansion to an order of nuns, the Religious of the Assumption. The sisters converted the mansion into a school and named it Ravenhill Academy.
Weightman died at the age of 90 years on August 25, 1904 at his Ravenhill Mansion in Philadelphia, Pennsylvania.
A posthumous portrait of William Weightman was also commissioned by his daughter Anne Weightman from the Swiss-born American artist Adolfo Müller-Ury; it was exhibited at the Corcoran Gallery in Washington and in Philadelphia in 1908.
The University of Pennsylvania gymnasium, Weightman Hall (1903–05, Frank Miles Day, architect), adjacent to Franklin Field, is named for him.