Hydrogen peroxide is one of the best, least harmful, and most convenient agents for preserving syrups, wine, beer, cider, and vinegar. For this purpose 2.5 fluidrachms of the commercial peroxide of hydrogen may be added to each quart of the article to be preserved. Hydrogen peroxide also affords an easy test for bacteria in water. When hydrogen peroxide is added to water that contains bacteria, these organisms decompose it, and consequently oxygen gas is given off. If the water be much contaminated the disengagement of gas may be quite brisk.

To Preserve Milk (which should be as fresh as possible) there should be added enough hydrogen peroxide to cause it to be completely decomposed by the enzymes of the milk. For this purpose 1.3 per cent, by volume, of a 3 per cent hydrogen peroxide solution is required. The milk is well shaken and kept for 5 hours at 122° to 125° P. in well-closed -vessels. Upon cooling, it may keep fresh for about a month and also to retain its natural fresh taste. With this process, if pure milk is used, the ordinary disease germs are killed off soon after milking and the milk sterilized.