CONCENTRATED MUSTS MEASURED AT T C WITH A PYCNOMETER OR A HYDROMETER OF ORDINARY GLASS TO RELATE THE RESULT TO 20 C ( SEE O.J . )
TABLE VII
TEMPERATURE CORRECTIONS C TO THE DENSITY OF WINES OF 13 % VOL OR MORE MEASURED WITH A HYDROMETER OR A PYCNOMETER OF ORDINARY GLASS AT T C TO RELATE THE RESULT TO 20 C ( SEE O.J . )
CONVERSION OF THE SPECIFIC GRAVITY TO THE DENSITY
TABLE VIII ( SEE O.J . )
RELATIONSHIP BETWEEN THE SPECIFIC GRAVITIES CORRECTED FOR THE BUOYANCY OF AIR AND THE UNCORRECTED SPECIFIC GRAVITIES
TABLE IX ( SEE O.J . )
1.5 . SUPPLEMENT TO THE REFERENCE METHOD _ MEASUREMENT BY PYCNOMETER ON SINGLE-PAN BALANCE
PRINCIPLE
THE REFERENCE METHOD FOR THE DETERMINATION OF THE DENSITY OF MUSTS AND WINES AND FOR THE DETERMINATION OF THE ALCOHOLIC STRENGTH OF WINES REQUIRES THE USE OF A TWO-PAN BALANCE AND A PYCNOMETER WITH ITS TARE BOTTLE OF THE SAME EXTERNAL VOLUME TO ELIMINATE THE EFFECT OF AIR . THIS SIMPLE TECHNIQUE MAY ALSO BE APPLIED WHEN A SINGLE-PAN BALANCE IS USED SUBJECT TO A SUPPLEMENTARY WEIGHING OF THE TARE BOTTLE TO TAKE ACCOUNT OF THE VARIATIONS OF THE BUOYANCY OF AIR :
_ WHEN ESTABLISHING THE PYCNOMETER CONSTANTS : WEIGHT OF THE EMPTY PYCNOMETER , VOLUME AT 20 C , THE WEIGHT T0 OF THE TARE BOTTLE IS DETERMINED ;
_ WHEN DETERMINING DENSITY , THE WEIGHT T1 OF THE TARE BOTTLE IS AGAIN DERIVED AND THE WEIGHT OF THE PYCNOMETER FILLED WITH LIQUID IS CORRECTED FOR THE MATHEMATICAL VALUE OF THE DIFFERENCE BETWEEN T0 AND T1 . THE REMAINDER OF THE CALCULATIONS ARE UNCHANGED .
PROCEDURE
1 . STANDARDIZATION OF THE PYCNOMETER
ESTABLISH THE FOLLOWING CONSTANT CHARACTERISTICS OF THE PYCNOMETER :
_ ITS WEIGHT EVACUATED , P0 ,
_ ITS VOLUME AT 20 C , V20 ,
_ AT THE SAME TIME , RECORD ACCURATELY THE WEIGHT OF THE TARE BOTTLE T0 .
THE WEIGHT OF THE TARE BOTTLE T0 IS OBTAINED BY WEIGHING TO THE NEAREST 0 * 1 MG .
THE WEIGHT OF THE PYCNOMETER EVACUATED , P0 , IS THE WEIGHT P OF THE CLEAN AND DRY PYCNOMETER , FILLED WITH AIR , LESS THE MASS M OF THE AIR WHICH IT CONTAINS . OBTAIN THE MASS M OF THE AIR BY 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