COLLABORATIVE DETERMINATION OF SPECIFIC-GRAVITY BY DENSITY METER

A method employing a density meter for the determination of specific g ravity (SG) has been tested for the determination of the gravity (G) o f beer, aqueous sugar solutions and aqueous ethanol solutions by the A nalysis Committee of the Institute of Brewing. The term ''gravity'', u sed throughout this report is defined by the equation G = SG x 1000. R epeatability (r(95)) and reproducibility (R(95)) values were calculate d over the range 994.6 to 1124.2 gravity. For beer, it was judged that precision values were independent of the gravity of the sample. Value s for r(95) and R(95) were 0.1 and 0.9, respectively, for instruments with a 5 figure display and 0.08 and 0.32, respectively, for instrumen ts with a 6 figure display, over the range 999.1 to 1017.0 gravity, Fo r solutions of ethanol in water, precision was also independent of the gravity of the sample. Values for r(95) and R(95) were 0.1 and 0.3, r espectively, for instruments with a 5 figure display and 0.05 and 0.19 , respectively, for instruments with a 6 figure display, over the rang e 994.6 to 999.1 gravity. For aqueous sugar solutions the values of r( 95) and R(95) increased with increasing gravity. At 1049.3 gravity, va lues for r(95) and R(95) were 0.1 and 0.8, respectively, for instrumen ts with a 5 figure display and 0.07 and 0.35, respectively, for instru ments with a 6 figure display. At 1124.2 gravity values for r(95) and R(95) were 0.2 and 1.4, respectively, for instruments with a 5 figure display and 0.16 and 1.35, respectively, for instruments with a 6 figu re display.