For all that, unless great care and attention be exercised, a whole-fruit jam ought not to be made on a too violent fire, lest it burn. Conversely, when jellies are in question, wherein the juice alone of the fruit is treated, the fire should be as intense as possible; in order that the required degree of consistence, which marks the close of the operation, may be reached as speedily as possible.
The degree of consistence is the same for all jellies, and may be ascertained thus: when the steam given off by the preparation loses its density, and the boiling movement becomes perceptible, it may be concluded that evaporation has ceased, and that the real cooking-process, which is very rapid, has begun. At this stage frequently take the skimmer out of the saucepan.
The jam adhering to it falls off, at first very quickly; then, in a few minutes, it is seen to accumulate towards the centre of the skimmer and to fall therefrom slowly at lengthy intervals, in large drops.
This stage, which is indubitably indicative of the cooking being at an end, is called the “nappe” and is equivalent to the [large-thread] stage in the cooking of sugar; and, as soon as it is reached the jam should be taken off the fire. Allow it to cool for seven or eight minutes, and pour it into pots, which, if of glass, should be gradually heated, lest they crack.
The following day, set a round piece of white paper saturated with rectified glycerine, on each pot, and drop these pieces of paper directly upon the jam. Rectified glycerine will be found preferable by far to the commonly-used sugared brandy.
Then close the pots with a double sheet of paper, fastened on with string, and place them somewhere in the dry.
[2956—APRICOT JAM]
Cut the apricots in two, and use very ripe fruit, grown in the open, if possible. Break the stones, skin the almonds, and cut them in two. Allow three-quarters lb. of loaf-sugar per lb. of fruit. Put this sugar in a preserving pan with one-third pint of water per [822] ]two lbs. of sugar, and, when the latter is dissolved, boil for a few minutes, carefully skimming the while. Add the apricots, set the whole to cook on a moderate fire, and stir incessantly, especially towards the end, when the jam is more particularly prone to burn on the bottom of the saucepan. Take the jam off the fire as soon as it reaches the “[nappe]” stage, as explained above, and mix the almonds with the jam.
[2957—CHERRY JAM]
Stone the cherries, and allow one and a half lbs. of loaf-sugar per two lbs. of the fruit; taking care to have equal weights of sugar and fruit if the latter be not over sweet. Put the sugar in the preserving pan; moisten it with water that it may dissolve, and boil it for five minutes, skimming carefully the while. Add the cherries and a half-pint of red-currant juice, and cook over a fierce fire until the “[nappe]” stage is reached.