MULTIPLYING THE DENSITY OF THE AIR BY THE VOLUME OF THE PYCNOMETER . UNDER AVERAGE CONDITIONS OF TEMPERATURE AND PRESSURE ASSUME A VALUE OF 0.0012 G/ML FOR THE DENSITY OF AIR . FOR THE CALCULATION OF M , CONSIDER THAT THE VOLUME OF THE PYCNOMETER IS NUMERICALLY EQUAL TO P1 - P , P1 BEING THE WEIGHT OF THE PYCNOMETER FILLED WITH WATER OBTAINED AT THE TIME OF THE DETERMINATION OF THE WEIGHT OF WATER IN THE PYCNOMETER AT T* C .
HENCE : P0 = P - M , WHERE M = 0.0012 ( P1 - P ) .
TO OBTAIN THE VOLUME AT 20* C OF THE PYCNOMETER , DETERMINE THE WEIGHT P1 OF THE PYCNOMETER , FILLED UP TO THE MARK WITH DEGASSED WATER AT T* C . THIS TEMPERATURE MUST BE MEASURED TO 0.02* C .
THE MASS MT OF THE WATER AT T* C CONTAINED IN THE PYCNOMETER IS EQUAL TO :
MT = P1 - P0
MULTIPLY MT BY THE FACTOR F ( PRODUCT OF THE RECIPROCAL OF THE DENSITY OF THE WATER AT T* C AND THE RATIO OF THE VOLUMES OF THE PYCNOMETER AT T* C AND AT 20* C ) GIVEN IN TABLE I ( PAGE 5 ) TO OBTAIN THE VOLUME OF THE PYCNOMETER AT 20* C :
V20 = F ( P1 - P0 )
2 . DETERMINATION OF A DENSITY
WEIGH THE TARE BOTTLE TO THE NEAREST 0.1 MG ; LET THIS WEIGHT BE T1 .
FILL THE PYCNOMETER WITH LIQUID ( MUST , WINE OR DISTILLATE ) AT T* C AND WEIGH ; LET THIS BE P2 .
CALCULATE THE DIFFERENCE DT = T1 - T0 ; THIS REPRESENTS THE VARIATION IN THE BUOYANCY OF AIR .
THE MASS LT OF THE LIQUID CONTAINED IN THE PYCNOMETER AT T* C IS EQUAL TO LT = P2 - ( P0 + DT ) .
NOTE MUST BE TAKEN OF THE SIGN OF DT . THE APPARENT DENSITY * IS EQUAL TO THE RATIO OF LT TO V20 .
ONCE THE APPARENT DENSITY AT T* C IS KNOWN , THE DENSITY AT 20* C OF THE LIQUID UNDER TEST ( DRY WINE , MUST OR CONCENTRATED MUST , SWEET WINE CONTAINING RESIDUAL SUGARS , ALCOHOL-FREE RESIDUE ) IS DETERMINED AS SPECIFIED ON PAGE 6 .
NUMERICAL EXAMPLE
1 . STANDARDIZATION OF THE PYCNOMETER :
WEIGHT OF TARE BOTTLE : T0 = 171.9160
WEIGHT OF PYCNOMETER FILLED WITH AIR : P = 67.7913
WEIGHT OF PYCNOMETER FILLED WITH WATER AT 21.65* C : P1 = 169.2715
MASS OF AIR CONTAINED IN THE PYCNOMETER : M = 0.0012 ( 169.2715 - 67.7913 ) = 0.1218
WEIGHT OF EMPTY PYCNOMETER : P0 = 67.7913 - 0.1218 = 67.6695
VOLUME OF THE PYCNOMETER AT 20* C : V20 = 1.002140 ( 169.2715 - 67.6695 ) = 101.8194 ML OR 0.1018194 DM3
2 . DETERMINATION OF THE APPARENT DENSITY OF A WINE :
WEIGHT OF TARE BOTTLE AT THE TIME OF THE DETERMINATION :