This fantastic jam recipe originally came from a Better Homes and Gardens canning magazine, as did the tip about making peach bellini floats with it. I added the butter to help tame the foaming. Use your tallest stockpot for this recipe - even with the butter it foams up a lot! Do not increase the amount of butter as this could lower the acidity of your recipe too much and make it unsafe for canning. Bottled lemon juice has a more consistent acid level then fresh lemon juice and is the preferential choice for canning recipes. Cooking time listed is processing time and this will vary depending on your altitude (consult a trusted source such as the Ball Blue Book for an altitude adjustment chart).