Litmus test (politics) Litmus test (politics) A litmus test is a question asked of a potential candidate for high office, the answer to which would determine whether the nominating official would proceed with the appointment or nomination. The expression is a metaphor based on the litmus test in chemistry, in which one is able to test the general acidity of a substance, but not its exact pH. Those who must approve a nominee, such as a justice of the Supreme Court of the United States, may also be said to apply a litmus test to determine whether the nominee will receive their vote.
Fractional crystallization (chemistry) Fractional crystallization (chemistry) In chemistry, fractional crystallization is a method of refining substances based on differences in solubility. It fractionates via differences in crystallization (forming of crystals). If a mixture of two or more substances in solution are allowed to crystallize, for example by allowing the temperature of the solution to decrease or increase, the precipitate will contain more of the least soluble substance. The proportion of components in the precipitate will depend on their solubility products. If the solubility products are very similar, a cascade process will be needed to effectuate a complete separation. This technique is often used