So-called hard waters should not be used in making a brine. The presence of large quantities of calcium salts and possibly other salts found in many natural waters may prevent the proper acid formation, thus interfering with normal curing. The addition of a small quantity of vinegar serves to overcome alkalinity when hard water must be used. If present in any appreciable quantity, iron is objectionable, causing a blackening of the pickles under some conditions. SHRIVELING Shriveling of pickles often occurs when they have been placed at once in very strong salt or sugar solutions, or even in very strong vinegars. For this reason avoid such solutions so far as possible. When a strong solution is desirable the pickles should first be given a preliminary treatment in a weaker solution. This difficulty is most often encountered in making sweet pickles. The presence of sugar in high concentrations is certain to cause shriveling unless EFFECT OF TOO MUCH SALT ON SAUERKRAUT Perhaps the most common cause of failure in making sauerkraut is the use of too much salt. The proper quantity is 2| per cent by weight of the cabbage packed. When cabbage is to be fermented in very warm weather it may be well to use a little more salt. As a rule, however, this should not exceed 3 per cent. In applying the salt see that it is evenly distributed. The red streaks which are sometimes seen in sauerkraut are believed to be due to uneven distribution of salt. EFFECT OF SCUM Spoilage of the top layers of vegetables fermented in brine is sure to occur unless the scum which forms on the surface is frequently removed. This scum is made up of wild yeasts, molds, and bacteria, which, if allowed to remain, attack and break down the vegetables beneath. They may also weaken the acidity of the brine, in which way they may cause spoilage. The fact that the top layers have spoiled, does not necessarily mean, however, that all in the container are spoiled. The molds and other organisms which cause the spoilage do not quickly get down to the lower layers. The part found in good condition often may be saved by carefully removing the spoiled part from the top, adding a little fresh brine, and pouring hot paraffin over the surface. EFFECT OF TEMPERATURE Temperature has an important bearing on the success of a lactic fermentation. The bacteria which are essential in the fermentation of vegetable foods are most active at a temperature of approximately 86° F., and as the temperature falls below this point their activity correspondingly diminishes. It is essential, therefore, that the foods be kept as close as possible to 86° F. at the start and during the active stages of a fermentation. This is especially important in the production of sauerkraut, which is often made in the late fall or winter. The fermentation may be greatly retarded or even stopped by too low a temperature.