The volume of brine necessary to cover vegetables is about half the volume of the material to be fermented. For example, if a 5-gallon keg is to be packed, 2½ gallons of brine is required. Table 2.--_Freezing point of brine at different salt concentrations_ ----------+-------------+------------ Salt | Salinometer | Freezing | reading | temperature ----------+-------------+------------ _Per cent_| _Degrees_ | °_F_ 5 | 20 | 25.2 10 | 40 | 18.7 15 | 60 | 12.2 20 | 80 | 6.1 25 | 100 | 0.5 ----------+-------------+------------ Table 3.--_Density of sugar sirup_ ---------+--------------- | Quantity of | sugar for Density | each gallon | of water[4] ---------+--------------- _Degrees | Brix or | Balling_ | _Lbs._ _Ozs._ 5 | 7 10 | 14.8 15 | 1 7.5 20 | 1 14.75 25 | 2 12.5 30 | 3 9 40 | 5 8.75 45 | 6 13 50 | 8 5.25 55 | 10 4 60 | 12 8 ---------+--------------- [4] When vinegar is used, the equivalent sugar hydrometer reading would be about 2 degrees higher than that indicated in the table. Table 4.--_Number of cucumbers of various sizes required to make a gallon of pickles_ -------------------+----------------+----------- | | Number to Size | Variety | a gallon -------------------+----------------+----------- 1 to 2 inches long | Gherkins[5] | 250 to 650 2 to 3 inches long | Small pickles | 130 to 250 3 to 4 inches long | Medium pickles | 40 to 130 4 inches and longer| Large pickles | 12 to 40 -------------------+----------------+----------- [5] Small pickles are usually designated as gherkins. Those of very small size are sometimes called midgets. The maximum acidity formed by a lactic fermentation of vegetables in brine varies from 0.25 to 2 per cent. The maximum is reached at or soon after the close of the active stage of fermentation. After this the acidity usually decreases slowly. The stage of active fermentation continues for from one to three weeks, depending upon the temperature, strength of brine, etc. During this period gas is formed and froth appears on the surface, owing to the rising of gas bubbles. At the close of this period the brine becomes "still." The quantity of acid formed depends primarily upon the sugar content of the vegetables fermented, but it may be influenced by other factors. Dipping a piece of blue litmus paper (obtainable at drug stores) in the brine will show whether the brine is acid. If the paper turns pinkish or red, the brine is acid, but the litmus paper does not give a definite indication of the degree of acidity.