Microcosmical, Microcosmic adj. Of or pertaining to the microcosm. Microcosmic salt (Chem.), a white crystalline substance obtained by mixing solutions of sodium phosphate and ammonium phosphate, and also called hydric-sodic-ammonic-phosphate. It is a powerful flux, and is used as a substitute for borax as a blowpipe reagent in testing for the metallic oxides. Originally obtained by the alchemists from human urine, and called sal microcosmicum.