A scale used on some sorts of hydrometer on which 0o is the point to which the instrument goes down in water and 10o the point to which it goes down in a 10% solution of NaCl at 12. 5oC
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}