To wash out the last bits of jam from a jar, I add water, put on the lid and shake it vigorously. Too little water and the remnants aren鈥檛 easily dislodged because there isn鈥檛 enough 鈥渙omph鈥� in the water. Too much has the same result because there is no space for the 鈥渙omph鈥� effect to kick in. What are the optimum proportions of water, jam and empty capacity?
Ken Hawkins, Sheffield, South Yorkshire, UK