. Principes de la chimie agricole [microforme] . absorber les quantités suivantes d'hygroscopichumidite: Hygtoscopic humiliquePar cent. Sols sablonneux (moins de 5 pour cent, argile) 3 Loams sableux 3-5 loams 5 Loams d'argile ... 5-7 argile 7-10 la quantité d'eau hygroscopique prise par une sous-position donnée dépend en partie de sa surface. Une masse de quartzwill absorbe beaucoup plus d'humidité lorsqu'il est en poudre fine que lorsqu'il est en gros fragments. Il est également fortement influencé par le caractère amountaand des constituants colloïdes dans le sol, tels que l'oxyde ferrique ashydraté, l'alumine, la silice gélatineuse, la silice hydratée

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. Principles of agricultural chemistry [microform] . absorb the following amounts of hygroscopicmoisture: Hygtoscopic moisturePer cent. Sandy soils (less than 5 per cent, clay) 3 Sandy loams 3-5 Loams 5 Clay loams ... 5-7 Clay 7-10 The amount of hygroscopic water taken up by a given sub-stance depends partly upon its surface area. A mass of quartzwill absorb much more moisture when in fine powder than whenin large fragments. It is also greatly influenced by the amountand character of the colloid constituents in the soil, such ashydrated ferric oxide, alumina, gelatinous silica, hydrated silicates, and especially humus. Pure clay has a somewhat lower absorp-tive power than these. Value of Hygroscopic Moisture.—Plants are not able to utilizethe hygroscopic moisture of soils. At least, they wilt before themoisture in the soil is withdrawn to the amount held byhygroscopic power. Heinrich- grew plants in very small boxes until well developed Rep. Cal. Exp. Sta., 1897-8. - Jahresber, f. Agr. Chera., 1875-6, p. 368. the; soiIv and wati^r 129. and then placed them under conditions of very little evaporationuntil they began to wilt. The moisture in the soil was thendetermined. The hygroscopic moisture was also determined bythe method already indicated. A variety of soils and plants wereused. The following table shows the average results secured withIndian corn and oats : Water per 100 of dry soil Coarse sandy soil ■Sandy garden soilFine humus sand ■ Sandy loam Calcareous soil ■ - •Peat It appears that hygroscopic water may be of advantage inregions of hot, dry winds; the higher the hygroscopic water, theless rapidly the soil dries out and heats up. It also appears thatheavy fogs, such as occur in parts of California, may add to thehygroscopic water of the soil, and keep the plant growing slowlywhen rainfall is lacking. Capillary Moisture.—This is the thin film of water surround-ing the soil particles and so held between them that it cannot flowofif. In a clean gla

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