In bottling jam It is not necessary to use the same amount of care in having the jars absolutely air-tight, as it is in canning fruit or vegetables, as such a high percentage of sugar is used that the sugar acts as a preservative, and provided the jam is cooked sufficiently and stored in a dry, cool place, there ought to be no trouble with mould or fermentation. It is therefore useful to know how to make use of ordinary bottles, especially in these days when the cost of vacuum jars is very high, and the following, taken from a Bulletin on "Fruit and Vegetable Bottling" by Vincent and Georgiana Banks, published in England, will prove valuable.
"Clarified mutton fat is a very old-fashioned material for sealing, and is quite good if carefully done, but if the bottle is shaken during the cooling, it does not stick to the glass, and when cold the juice will be seen oozing up round the edge. Some complain that the fat occasionally mixes with the fruit; this can be got over by cutting paper to fit inside the neck of the bottle, and dipping the paper in the melted fat with a pair of scissors, and laying it directly on top of the water. Dipping it in the hot fat makes the paper waterproof and sterilises it at the same time. After the paper has been put in, pour fat on top of it to about 3/4 to 1 inch thick, and stand it aside until next day. Only do one bottle at a time, and do it as quickly as possible. Do not pour the fat on if fumes are rising from it, as it is then too hot and will splutter. If a speck of juice shows through the next day, gently scrape it and pour another thin layer over the top; this usually puts things right. Tie down with ordinary paper to keep the dust away, and store.
Another inward seal is salad oil. Make it just hot and pour it about 3/4 of an inch, and tie over with paper to prevent its spilling. To remove the oil before using the fruit, get a basin and give the bottle a sharp twist, when nearly all the oil will fall into the basin and can Be saved. To get the few remaining drops of oil away a piece of cotton wool will absorb it readily.
Corks are the next inward seal. Put them into the bottles with some sort of greaseproof paper under them. They should be well scalded first, and then driven firmly in. Trim away any roughness or paper from the top, and paint over with - or better still dip into - some melted bottle wax, paraffin wax, or resin, so as to close up all pores and fill in the junction between the cork and bottle's neck.
Passing now to the outward seals, the first place must be given to the old-fashioned bladder. It is quite waterproof, and consequently the bottles may be moved about freely if necessary. Cut the bladder to the required size and soak it in cold or tepid water, wipe it and stretch it tightly over the bottles, and tie it down very tightly.
There is also vegetable parchment, but the best is not nearly so good now as it was a few years ago, so we have to give it help. First damp and wipe the parchment dry - this makes it soft and pliable. Then tie it very tightly over the bottle, and to strengthen the parchment and fill up the pores, either gum it all over and all round, brushing it over with starch or flour and water paste, or white of egg, or ordinary painters varnish, in fact, anything that will close up the pores and strengthen the parchment.
Ordinary paper may be used, but it should not be too thick. Paper from a writing pad is quite good, bat three layers of it are necessary; cut two pieces to come well down round the neck and one just to cover the top. Now make some flour and water paste, or mix some starch fairly thick, or get a bottle of gum, and press the first pieces of paper on to the bottle so as to get the size; then paint it all over, except the centre, with some of the seal stuffs mentioned, and press firmly round the neck of the bottle. Then take the small piece of paper and paste that all over and press it over the top. Lastly, paste the third piece over and press firmly over all, and paste the outside of the paper to finish off. This may read rather a long process, but it is not so really. The details have been given purposely, as when once you have acquired the habit you can almost go about it blindfold. Another way is to mix a little paste with flour and cold water to the consistency of thick cream, brush it evenly over, and use the three layers of paper, putting each one on separately.
Another excellent way is to get 1 lb. of resin, 2 ozs. tallow, 2ozs. beeswax, and melt them all together. Then get some stout cloth or linen and cut it to the required size and paint the mixture freely on; it will set quite hard. A large number may be done at one time and stored away, ready for use at any time. All that is required is to place one over the bottle as soon as it is taken out of the pan or oven, when the heat from the bottle will soften the mixture. Press the seal firmly round the bottle, tie round, and it will set and stick quite fast. This method has the great ad vantage over all the other seals that it can be prepared beforehand. Should a drop of the resin fall into the water it sets and floats on the top and does not matter, but this may be avoided by cutting a small piece of paper and laying it across the bottle before pressing the seal on. A good way to melt the resin, tallow, and beeswax together is to put them into a jar, and the jar into a pan of water before putting it on the fire.