Preserves and jams are so nearly alike that it is hard to draw a definite line of distinction. If there is any difference it lies in the fact that preserves are usually so prepared that the fruit, either sliced or whole, is as little broken as possible and rests in a clear, thick fruit juice; while jam is, as its name would imply, a thick and well mashed compote.
When cooking jam or preserves, the fruit is generally cooked alone or with a very little water, unless recipe calls for sugar to draw out the juice if no water is needed. As in making jelly, sugar should be added at two different times; this prevents fruit from hardening if it has to cook a long time, and insures successful thickening of the fruit after last sugar is added. In fact, some fruits may stay thin after the second part of the sugar is added, not because the recipe is faulty or a mistake has been made, but just because the fruit lacked the right amount of gelatinizing power. If dependent on the markets, the right quality of fruit cannot always be secured. In this case a few extra spoonfuls of sugar can be added and the preserves taken from stove as soon as it is dissolved. If it still fails to thicken, use this thin batch as a foundation for another time, adding unripe fruit of some kind, as directed in jelly making. The proportions given in these recipes are for a rich, fruity preserve, and, as has been said, all fruits do not congeal in the same length of time, so a little longer cooking after the first amount of sugar is added may be necessary if fruit is quite watery, and the final cooking must be determined by testing jam on a cold saucer; if it forms a clear, thick jelly, it is done.
Many cooks keep jams and preserves in crocks, covering them with a piece of paper dipped in brandy, and a plate, but a nicer way is to put them in selfsealing jars. Jam, like jelly, should stand covered with cheesecloth for one or more days to harden before closing. Although each recipe has methods and proportions given, it is well to refer to these instructions if any point is not clear.
Method. Thoroughly heat the blackberries over a moderate fire, then press through a coarse sieve. Measure, and to each pint of pulp add half a pound of sugar. Boil rapidly for twenty minutes, stirring occasionally to prevent scorching. Pour into jars and seal as other jam.
Method. Snip stem and blossom from perfectly green, unripe gooseberries, place in kettle and pour in enough water just to show through top of berries. Boil gently until fruit is tender. Measure, and to every one and a quarter cups of fruit use one cup of sugar. Boil the fruit ten minutes, then add half the sugar and cook ten minutes. Add rest of sugar, and after fruit looks clear and thick, test on a saucer. If it jellies as soon as cold, it is done. Place in scalded glasses and 6eal after one or two days.
Method. Use above dimensions, but cook slowly a long time until perfectly stiff. A few slices of lemon or orange and a teaspoon of ground cloves and cinnamon will improve the taste.
Method. Use above proportions, but take one third quinces to two thirds apples. Let the quinces simmer for a while before adding apples, as they require more cooking
Method. Double the above proportions, and let simmer at least three hours before adding any sugar. Continue to cook with sugar until the butter is so thick that it will stand stiff if dropped on a plate. If a very spicy butter is wanted, add to mixture two teaspoons of ground cinnamon and cloves.