1911 Encyclopædia Britannica/Microcosmic Salt

MICROCOSMIC SALT, or ammonium sodium hydrogen or tho phosphate, NH₄NaHPO₄.4H₂O, so named by the alchemists because it is contained in the decomposing urine of man (the “microcosm”). It is interesting historically as being the raw material from which Brand prepared phosphorus, whence it is also called “salt of phosphorus.” It may be obtained in large transparent crystals from a mixture of solutions of sal-ammoniac and disodium phosphate, or by saturating a solution of monosodium phosphate with ammonia. When heated to redness, it leaves a transparent glass of sodium metaphosphate, NaPO₃, which like borax dissolves most metallic oxides, with formation of glasses that often exhibit characteristic colours, and which may be used in the qualitative analysis of substances. (See Chemistry, § Analytical.)