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leaching

(Encyclopedia)leaching, method of extraction in which a solvent is passed through a mixture to remove some desired substance from it. A simple example is the passage of boiling water through ground coffee to dissol...

thermography

(Encyclopedia)thermography thûrˌmŏgˈrəfē [key], contact photocopying process that produces a direct positive image and in which infrared rays are used to expose the copy paper. In a specially designed machine...

shellac

(Encyclopedia)shellac, solution of lac in alcohol or acetone. In commerce the name is applied to the resinous substance (lac) itself rather than to the solution. It ranges in color from orange to light yellow depen...

phlogiston theory

(Encyclopedia)phlogiston theory flōjĭsˈtŏn [key], hypothesis regarding combustion. The theory, advanced by J. J. Becher late in the 17th cent. and extended and popularized by G. E. Stahl, postulates that in all...

psychosis

(Encyclopedia)psychosis sīkōˈsĭs [key], in psychiatry, a broad category of mental disorder encompassing the most serious emotional disturbances, often rendering the individual incapable of staying in contact wi...

amphoterism

(Encyclopedia)amphoterism ămˌfətĕrˈĭzm [key], in chemistry, the property of certain substances of acting either as acids or as bases depending on the reaction in which they are involved. Many hydroxide compou...

naphthalene

(Encyclopedia)naphthalene năfˈthəlēnˌ [key], colorless, crystalline, solid aromatic hydrocarbon with a pungent odor. It melts at 80℃, boils at 218℃, and sublimes upon heating. It is insoluble in water, som...

Reichstein, Tadeus

(Encyclopedia)Reichstein, Tadeus tädĕˈo͞osh rīkhˈshtīn [key], 1897–1996, Swiss organic chemist, b. Vlotslavsk, Russia (now Włocławek, Poland), educated at the technical school in Zürich, where he also t...

teleology

(Encyclopedia)teleology tĕlˌēŏlˈəjē, tēˌlē– [key], in philosophy, term applied to any system attempting to explain a series of events in terms of ends, goals, or purposes. It is opposed to mechanism, th...

toluene

(Encyclopedia)toluene mĕthˌəlbĕnˈzēn [key], C7H8, colorless liquid aromatic hydrocarbon that melts at −95℃ and boils at 110.8℃. It is insoluble in water but highly soluble in most organic solvents. Tolu...