METRICATION 453 UNITS TO BE ALLOWED IN CONJUNCTION WITH SI physical name symbol definition quantity of unit for unit of unit length parsec pc 30.87 X 10 •5 m area barn b 10 -28 m 2 hectare ha 104 m 2 volume litre 1 10 -3 m 3 pressure bar bar 105 N m -2 mass tonne t 103 kg ----- 1 Mg kinematic viscosity stokes St 10 -4 m 2 s -• diffusion coefficient dynamic viscosity poise P 10 -• kg m -• s -• magnetic flux density gauss G 10 -4 T (magnetic induction) radioactivity curie Ci 37 X 109 s -• energy electronvolt eV 1.6021 X 10 -•9 J The common units of time [e.g. hour (h), year] will persist, and also, in appropriate contexts, the angular degree. Until such time as a new name may be adopted for the kilogramme as the basic unit of mass, the gramme will often be used, both as an elementary unit (to avoid the absurdity of mkg) and in association with numerical prefixes, e.g. •g. EXAMPLES OF UNITS CONTRARY TO SI, WITH THEIR EQUIVALENTS* physical quantity length area volume unit equivalent Kngstr6m 10 -•ø m inch 0.0254 m foot 0.3048 m yard 0.9144 m square inch 645.16 mm 2 square foot 0.092 903 m 2 square yard 0.836 127 m21 cubic inch 1.638 71 X 10 -5 m 3 cubic foot 0.028 316 8 m 3 U.K. gallon 0.004 546 092 m 3 U.S. gallon 0.003 785 41 m 3 fluid ounce 28.413 1 cm 3 Fuller lists are to be found in Anderton, P. and Bigg, P. H. Changing to the metric sy.stem. 2rid edn. (1967). (H.M. Stationery Office, London.)

454 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS mass pound 0.453 592 37 kg ounce 28.349 5 g dram 1.771 85 g grain 64.798 9 mg density pound/cubic inch 2.767 99 X 104 kg m -• pound/cubic foot 16.0185 kg m -• concentration ounce/gallon 6.236 02 g 1 -t force dyne 10 -s N poundal 0.138 255 N pound-force 4.448 22 N kilogramme-force 9.806 65 N pressure atmosphere 101.325 kN m -2 torr 133.322 N m -2 pound (f)/sq.in. 6894.76 N m -2 --6.894 76 kN m -2 inch of mercury 3386.39 N m -2 energy crg 10- 7 j therm 105.506 MJ calorie (I.T.) 4.1868 J calorie (15 øC) 4.1855 J calorie (thermochemical) 4.18 • ] B.t.u. 1055.06 J= 1.055 06 kJ foot poundal 0.042 140 l J foot pound (f) 1.355 82 J power horse power 745.700 ¾V=0.745 700 kW temperature degree Rankine -*0 øK degree Fahrenheit t /øF -.•-.ø s 1'/øC q- 32