those organisms already present; and second, to exclude others from entering.  The first we usually accomplish by cooking, and the second by sealing.  In order to live these organisms require three conditions; first, a particular temperature; second, a certain amount of moisture; third, the right kind of food.  By taking away all or anyone of these requirements we may stop the growth or, in other words, we may preserve the food.  For example:  with the familiar method of cold storage the factor of temperature is removed; in the drying of the fruits and vegetables the factor of moisture is removed; by salting the factor of food is taken away.

The fruits and vegetables, commonly preserved in the home, are divided into five classes: 

l.—­Canning. 2.—­Jellies. 3.—­Jams. 4.—­Marmalades and Butters. 5.—­Pickles.

[820 Mothers’ remedies]

Canning.—­Under this head there are four common methods: 

1.  Steaming.—­By this method the fruit is put into the sterilized jars, the jars filled with boiling water and the covers loosely set on.  Then the jars are set on small blocks of wood in a pan of cold water.  Cover this pan and let the water come to a boil and boil for 15 minutes.  Remove the jars and fill them with boiling water, if necessary.  Seal tightly.  Small berries, such as strawberries and raspberries, retain their color and are especially good done in this manner.  Whole tomatoes done in this way are especially attractive for winter salads, and corn will keep indefinitely.

2.  Boiling in Syrup.—­This is the common household method of preserving fruits, such as peaches and pears.  A syrup is prepared of sugar and water, into this the fruit is dropped and cooked until soft; it is then put into sterile jars, sufficient syrup added to fill jar and the jar then sealed.

3.  Preserving.—­This is the same as boiling in syrup, except that equal quantities of sugar and fruit are used.  Small fruits such as berries are usually done in this way.

4.  Cold Water Process.—­This is a simple and easy method to use, and is especially desirable for vegetables such as rhubarb.  Great care must be taken to use only perfect fruit, because in this method of canning bacteria are merely excluded, not destroyed, and if any are present in the food there is nothing to prevent it from spoiling.  If fruit is over-ripe, or not perfectly fresh one of the other methods, such as boiling or steaming, is preferable.

To Can by the Cold Water Process.—­Pack the fruit in a sterilized jar; pour over it water which has been boiled and cooled, seal your jar and keep in a cool place.  Sometimes a solution of salt and water is used in place of pure water.  When salt water is used food will need to be freshened by being allowed to stand in cold water for some time before using.  Vegetables, such as beans, put up in this way are very similar to the fresh product.