A Hydrated Lime Plant (Courtesy of the Palmer Lime and Cement Company, York, Pa.)
CHAPTER XII
LIME HYDRATE
Slaking Lime. The usual means of reducing fresh burned stone lime to a condition that makes even distribution upon land possible is by slaking. A few years ago considerable effort was made to create a market for lime pulverized by machinery, but the difficulty in excluding the moisture of the air so that packages would not burst has been in the way of developing a market. Slaking, by the addition of water to the fresh burned lime, is the common method of getting the required physical condition. When the slaking is done on the farm, the custom has been to distribute the lime in small piles in the field, placing the piles at such convenient distance apart that the lime, after slaking, could be spread easily with a shovel.
The water for slaking comes from rains, or from moisture in the air and earth. The method is wasteful and can be justified, if ever, only where farm-burned lime costs little per ton, and the nature of the soil is such that a relatively heavy application can be safely made. The distribution is necessarily uneven, and if the required amount goes upon all the surface, a great excess is sure to go upon a portion of it. Very often an excess of water puddles much of the lime in the pile, and lumps may be seen lying in ineffective form in the soil for years. The practice is responsible for much of the excessive application that brought the use of caustic lime into disrepute.
Slaking in Large Heaps. A preferable method is to put the lime in flat heaps of large size and about four feet deep, so that water may be applied or advantage be taken of rainfall. The value of the lime is so great that one can well afford to draw water and apply with a hose so that the quantity can be controlled with exactness. When fresh burned lime is perfectly slaked, each 56 pounds of pure lime becomes 74 pounds of hydrated lime, water furnishing the added weight.