The discovery of powder in the wrong place prompted a second emergency response in two days Friday in Center City.
The 18-story Municipal Services Building was evacuated after a powder spilled out of an envelope about 9 a.m., officials said.
The evacuation was later limited to the concourse of the tower at 1401 John F. Kennedy Blvd., and the all-clear was sounded at 10:20 a.m. after it was determined the powder was harmless.
Deputy Fire Commissioner Ernest Hargett said the beige substance spilled out of an envelope in a room where workers open water-bill payments. The envelope had been damaged and was in a sealed plastic Postal Service bag.
The woman who opened the envelope was taken from the building in a white hazmat-style suit to an ambulance for an on-site examination. She emerged about an hour later in her street clothes as workers were allowed to return.
On Thursday, the discovery of a white powder inside a balloon at the Liberty Bell Pavilion caused havoc around Independence Mall. The powder was later determined to be flour.
Television news reports Thursday night had suggested that a Food Network show might have been responsible for the Hazmat scare. The Food Network and the FBI denied the connection.
Chef vs. City, a Food Network program, was shooting at Independence Hall near the pavilion that houses the bell.
"However, no balloons were used in association with the production shoot, and no cooking ingredients or items that could be misconstrued to be a white powdery substance were part of the taping that occurred at this location," the network said in a statement.
The FBI never said the Food Network was connected to the event, spokesman J.J. Klaver said Friday.
Klaver said that about three ounces of flour - about the size of a small meatball - was packed into the balloon, found near Sixth and Chestnut Streets. An investigation is continuing.