Substitution
the act of substituting or putting one person or thing in the place of another to serve the same purpose.
In chemistry, a term denoting the replacing of one element or group of elements for another. It is the great agent, and covers nearly the whole field of chemical change, and is always attended with some alteration of properties in the compound, the alteration increasing with the amount of substitution. (1) When chlorine replaces hydrogen in marsh gas, forming hydrochloric acid and methyl chloride, (2) When an alcohol radical replaces chlorine, as in trichloride of phosphorus, 3Zn (C2H5)2+2PCl3 = 3ZnCl2+2P (C2H5) 34 (3) A basylous or chlorous radical is replaced one for the other, as when nitrate or silver is decomposed by chloride of sodium, (4) When hydrogen is replaced by an alcohol radical, as in the case of acting on ammonia with iodide of ethyl, H₂N + C₂HI = HI + H C2H5N. See SALT.