PER LITRE ) . THE COLOURING MATTER OF THE WINE SHOULD BE CHANGED BY THE ALKALINITY . IN THE CASE OF VERY ACID , SOUR WINES , ETC . ADD THE LIME UNTIL THE WINE IS CLEARLY ALKALINE TO PHENOLPHTHALEIN USED EXTERNALLY . ADD , IF NECESSARY , SOME INERT POROUS MATTER AND A DROP OF AN AQUEOUS SOLUTION , OF ONE PART PER 100 OF WATER-SOLUBLE SILICONE TO PREVENT FROTHING . COLLECT THE DISTILLATE IN THE SAME FLASK AS THAT USED FOR MEASURING OUT THE WINE , AND INTO WHICH HAS BEEN PLACED 10 ML OF DISTILLED WATER .
DISTILL AT LEAST 200 ML . SHAKE THE FLASK AND MAKE UP TO THE MARK AT THE SAME TEMPERATURE AS INITIALLY ( TO WITHIN 5 C ) .
NOTE :
NEUTRALIZATION MAY BE AVOIDED BY THE USE OF 10 G OF A STRONGLY BASIC ION EXCHANGE RESIN ( 50 TO 100 MESH ) SUITABLY WASHED WITH DISTILLED WATER AND SUPPORTED ON A GLASS FRIT TO RETAIN FINE PARTICLES .
THIS RESIN RETAINS ACETIC ACID , FREE AND COMBINED SULPHUR DIOXIDE AND CARBON DIOXIDE .
10 G OF RESIN IS EFFECTIVE FOR 30 DISTILLATIONS WHEN USED FOR NORMAL WINES . CARRY OUT REGENERATION USING A 5 % SODIUM HYDROXIDE SOLUTION AND SIX FLUSHINGS WITH DISTILLED WATER ( SEE DRAWING ) .
2 . MEASUREMENT OF SPECIFIC GRAVITY OF THE DISTILLATE : POUR THE DISTILLATE INTO A LEVEL GLASS CYLINDER OF 36 MM INTERNAL DIAMETER AND 320 MM HEIGHT . KEEP THE CYLINDER VERTICAL . PLACE A THERMOMETER AND HYDROMETER IN THE CYLINDER . READ THE THERMOMETER ONE MINUTE AFTER SHAKING , SO ENSURING EQUILIBRIUM TEMPERATURE OF CYLINDER , THERMOMETER , HYDROMETER AND DISTILLATE HAS BEEN REACHED . WITHDRAW THE THERMOMETER AND READ THE APPARENT DEGREE OF ALCOHOLIC STRENGTH AFTER ONE MINUTE . TAKE AT LEAST THREE READINGS USING A MAGNIFYING GLASS . CORRECT THE APPARENT DEGREE MEASURED AT T C FOR THE EFFECT OF THE TEMPERATURE WITH THE FOLLOWING TABLE .
WHEN MAKING THE OBSERVATIONS THE TEMPERATURE SHOULD NOT DIFFER FROM AMBIENT BY MORE THAN 5 C . IF A GREATER DIFFERENCE IS OBSERVED IT MAY BE AVOIDED BY USING A VACUUM FLASK .
INTERNATIONAL ALCOHOLIC STRENGTH BY VOLUME AT 20 C
TABLE OF CORRECTIONS TO BE APPLIED TO THE APPARENT DEGREE OF ALCOHOLIC STRENGTH TO CORRECT FOR THE EFFECT OF THE TEMPERATURE ( SEE O.J . )
SECOND USUAL METHOD
DENSIMETRY BY THE HYDROSTATIC BALANCE
THE DISTILLATION APPARATUS AND ITS METHOD OF OPERATION ARE THE SAME AS FOR THE FIRST USUAL METHOD .
THE APPARATUS , THE CALIBRATION OF THE FLOAT AND THE PROCEDURE HAVE BEEN DESCRIBED IN CONNECTION WITH THE MEASUREMENT OF THE DENSITY , BUT THE MEASUREMENT OF DENSITY OF THE DISTILLATE MUST BE MORE ACCURATE THAN THAT OF WINE . IT SHOULD BE OBTAINED AT LEAST TO THE NEAREST 5 BY 10-5 . IN ORDER TO ACHIEVE THIS RESULT ONE SHOULD USE A FLOAT OF AT LEAST 50 ML AND TAKE ALL NECESSARY PRECAUTIONS TO AVOID ANY