Saturation
2 of the 6 encyclopedias on this shelf carry an entry for Saturation. Both are reproduced below, so you can see where they agree and where they differ.
The Encyclopedia of Founding (1892)
A liquid is said to be saturated when it has taken up as large a quantity of a solid as it can dissolve, in which case the force of cohesion between the particles of the solid is equalled by the adhesion of the liquid and the solid to each other. Saturation means also the absorption of liquids by solids, the permeation of an element by other elements, etc. See SOLUBILITY. Scabbed Castings are castings on the surface of which rough and unsightly excrescences are found when the adhering sand has been removed. These imperfections arise from a variety of causes: such as imperfect venting; faults in the ramming; unsuitable material; too much coal; extreme moisture, and numerous other causes, all of which, in the great majority of instances, might be easily avoided if the intelligence of those engaged in their production was equal to the demands made on it. The moulders of to-day are deficient from both an intellectual and artistic point of view, and no substantial improvement in the quality of castings may be anticipated until a more rigorous system of apprenticeship and superior technical training shall have been adopted. This and this only will amplify the minds of our young men and enable them to intelligently trace cause and effect, and thus avoid the errors which, owing to their present ignorance, are now so frequent. See TECHNICAL EDUCATION FOR THE MOULDER; FACING-SAND; VENTING; RAMMING; CUTTING; CURRENT.
Collier's New Encyclopedia (1921)
the act of saturating, penetrating, or impregnating completely; the state of being saturated. In chemistry, that point at which a substance ceases to have the power of dissolving or combining with another. SATURDAY (from Anglo-Saxon Sæterdæg, Sæterndæg-Sæter, Sætern, for Saturn, and dæg, a day-the day presided over by the planet Saturn), the seventh or last day of the week; the day of the Jewish Sabbath.
What Has Changed in the Last Century
The core definition still stands: a saturated solution is one holding as much solute as it can dissolve at a given temperature. What has gone is the 1892 explanation that saturation is reached when "the force of cohesion between the particles of the solid is equalled by the adhesion of the liquid" — chemists now describe it as a dynamic equilibrium, with molecules leaving and rejoining the solid surface at equal rates, governed by thermodynamics rather than a balance of two attractive forces. Collier's 1921 note that saturation is also the point at which a substance ceases to combine with another survives in the everyday distinction between saturated and unsaturated fats, where a saturated chain is one carrying no more hydrogen. The word has since spread well beyond chemistry, to saturation of magnetic materials, the saturation of a colour, and saturation vapour pressure in meteorology.
Written for this edition, 2026.