Duffus came home one afternoon to find his wife in the kitchen making homemade jam. She had a few jars on the table, and was attempting to tape the vacuum hose on a lid, when Duffus arrived. “What are you doing, dear?” he asked, confused by the piles of twisted tape that clung to everything in the kitchen. Mrs. Redneck said that vacuum sealing the jars helps keep them fresher and tasting good longer. Duffus laughed as he put a large pot on the stove to heat up, then filled up the sink with water, took the vacuum and tape from his wife and said, “Let me show you how it’s done, dear.”
How was Duffus planning to vacuum seal the jars?
Answer
Duffus took the lids off the jam jars and placed them in the hot water, which caused the jam to expand in the jar. When they were hot, he removed them, put the lids back on and placed them in the cooler water in the sink, which caused the jam to contract. Since the lid was sealed tight, the air pressure inside was less than the pressure outside the jar, which created a sort of vacuum-sealed effect.
