NORTHUMBERLAND - On the 12th day of Christmas, the Joseph Priestley House will host its annual Twelfth Day holiday celebration.

From 1 to 4 p.m. Sunday, the English manor at 472 Priestley Ave., will be adorned in decorations depicting the late 1700s, when the influential chemist and his family resided at the estate. Volunteers will also be wearing homemade 18th century garb while serving traditional holiday refreshments, including wassail, a hot mulled cider and "twelfth cake."

"You know the song 'The Twelve Days of Christmas?' This is the 12th day and part of that celebration," said Tom Bresenhan, president of the Friends of Joseph Priestley House.

The 12 days of Christmas is considered, in religious terms, to be the holiday season that begins on Christmas Day and ends on Jan. 5 with the Feast of Epiphany. Some beliefs have the season overlapping into Jan. 6, the day Christians celebrate the arrival of the Magi.

According to Bresenhan, the annual event at the Joseph Priestley House began about 20 years ago. Every aspect of the event, from the food, music and clothing, is designed to transport visitors back to a Pennsylvania life more than two centuries ago. That includes authentic decor made with natural materials.

"The old house will be decorated as it would have been back then," Bresenhan said.

Priestley was an English chemist and theologian best known for his discovery of oxygen in 1774. Facing prosecution in England, Priestley moved his family to Northumberland in 1794, where he resided until his death in 1804. The site, featuring his house and laboratory, are declared a National Historic Landmark and National Historic Chemical Landmark.

Visitors of the Twelfth Day event will have the opportunity to tour the house and the laboratory. Unlike regular guided tours held on Saturdays and Sundays throughout the year, the house will be open for visitors to roam freely.

"People will tour the house at their own pace," Bresenhan said, adding that the most popular spot is Priestley's laboratory, where he has seen people spend their entire trip soaking in the history.

Bresenhan said the highlight of the event is a chemistry demonstration by Robert Blatchley. Scheduled from 1:30 to 2:30 p.m., Blatchley will demonstrate how chemistry was studied back in the 18th century.

Activities for children are also planned, included a scavenger hunt through the house.

Tickets are $6 for adults and $4 for children. Active military and their families are admitted for free.

"It's an interesting event, like walking into the house 200 years ago and joining the Christmas celebration," Bresenhan said.

For more information, call 473-9474 or visit the Joseph Priestley House website at www.josephpriestleyhouse.org.