— 72 — largely depends. Given a series of solid phases or salts, the relative proportions will remain constant in a solution until some one phase permanently disappears, provided that sufficient time has elapsed to fonn a saturated solution.

In practical irrigation the amount of water present in the soil must diSer from time to time, so that with a large quantity of water a saturated condition may not be arrived at. Any difference in amount of soluble salts found in the resulting drainage water may be traced to this cause.

The normal drainage water consists of a solution of almost constant constitution, representing the ionic saturation of the various salts contained in the soil over and above the amount held by the absorptive power of the particular soil mass through which it has been moving.

Following the examination of the salt given above, an analysis of the drainage water was made with the following results. It should be noted that no determination was made of the proportion of potassium, as the bases not calcium and magnesium were calculated to their equivalent in sodium : lion. Calcium carbonate ...