n. [ Of Egyptian or North African origin. ] (Chem. & Min.) A native double salt, consisting of a combination of neutral and acid sodium carbonate, Na2CO3.2HNaCO3.2H2O, occurring as a white crystalline fibrous deposit from certain soda brine springs and lakes; -- called also urao, and by the ancients nitrum. [ 1913 Webster ]

n. [ From Trone a steelyard. ] A toll or duty paid for weighing wool; also, the act of weighing wool. [ Obs. ] Nares. [ 1913 Webster ]

n. [ LL. See Tronage. ] An officer in London whose duty was to weigh wool. [ Obs. ] [ 1913 Webster ]