Milk may be preserved good in hot weather, for a few hours, by placing the jug which contains it in ice, or very cold water; or a pinch of bicarbonate of soda may be introduced into the liquid.

To accomplish this, strong lime water is introduced in a clear state to the water to be softened, the quantity being regulated according to the amount of bicarbonates in solution.

The immediate effect of this is that a proportion of the carbonic acid of the latter combines with the invisible lime of the clear lime water, forming a chalky precipitate, while the loss of this proportion of carbonic acid also reduces the invisible bicarbonates into visible carbonates.