General view of an unidentified employee at work in a laboratory at the Rohm and Haas Company home office located at West Washington Square in Philadelphia.

The Rohm and Haas Company was founded in 1907 in Esslingen,…

Map depicting the facility and grounds of the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of Philadelphia,…

Two views of exposure racks designed to test the weathering capabilities of varnishes and other products manufactured by the Rohm and Haas Company. The racks are positioned on the roof of the company's home office…

Exterior view of a section of the zinc chloride manufacturing facility (Building 4) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the…

General view of the west side of the sulphuric acid contact plant (Building 41) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the…

Exterior view of the west side of the aluminum plant at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

General view of the exterior of the warehouse facilities (Building 53) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast…

Exterior view of the storeroom (Building 18) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of Philadelphia,…

Exterior view of the southeast corner of the aluminum plant at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

Exterior view of the southeast corner of the Leukanol and Sorbanol manufacturing facility (Building 2) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the…

General view of the south side of the power house (Building 43) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

Exterior view of the sodium tungstate manufacturing facility (Building 34) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast…

Exterior view of a section of the sodium sulfide manufacturing facility (Building 26) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the…

Exterior view of a section of the sodium sulfide and glaubersalt manufacturing facility (Building 33) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the…

Exterior view of a section of the sodium sulfide crystals manufacturing facility (Building 30) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware…

Exterior view of a section of the sodium nitrate storage and nitric acid plant at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the…

General view of the exterior of the semi-works facility at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

Exterior view of a section of the semi-works at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of Philadelphia,…

Exterior view of the road and railroad track running between the copper oxide and aluminum manufacturing facilities at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located…

General view of the exterior of the orthochrome facility (Building 58) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast…

General view of the north side of the power house (Building 43) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

Exterior view of a section of the nitric acid manufacturing facility (Building 15) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the…

Exterior view of a section of the muriatic manufacturing facility at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast section of…

General view of the construction of the methol amines plant (Building 22) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in the Northeast…

General view of the exterior of the main office and laboratory facilities (Building 51) at the Charles Lennig and Company chemical manufacturing plant in Bridesburg, a neighborhood located along the Delaware River in…