EXAMINATION OF WINE. 53 



preservative, and by plastering. Plastering is rarely resorted to in 

 northern wine districts of Europe, and this is also probably true of 

 American wines. 



The maximum quantity of sulphuric acid allowed by the Weinstatis- 

 tik Commission is 0. 2 gram per 100 cc calculated to potassium sulphate. 



SULPHUROUS ACID. 



Sulphurous acid is sometimes, although rarely, added as sulphite as 

 a preservative and bleaching 1 agent, and a small amount is almost 

 always introduced in sulphuring the casks before the introduction of 

 the wine. This latter practice is not to be condemned, although the 

 amount of sulphur to be burned in the casks should be limited. 



It is now recognized that sulphurous acid exists in wine in two forms 

 free, and in combination \vith aldehyde, of which the latter is consid- 

 ered by far the least objectionable. There is considerable difference 

 of opinion concerning the amount of sulphurous acid which should be 

 permitted. The Bavarian Association considers wines too strongly 

 sulphured if 0.008 gram of sulphurous acid is present per 100 cc, while 

 the Swiss Association permits 0.02 gram of total sulphurous acid and 

 0.002 gram of free sulphurous acid per 100 cc. 



ANALYTICAL METHODS. 



EXAMINATION OF MUST. 



The ordinary determinations to be made in the examination of 



"must" are specific gravity, extract, reducing sugars, total acids, and 

 tannin. With the exception of the specific gravity, these determina- 

 tions are made according to the methods described under the examina- 

 tion of wines. 



Specific gravity is determined at the temperature of 15.6 by means 

 of the picnometer, small accurately graduated hydrometer, Westphal 

 balance, or Westphal plummet on the analytical balance. The first of 

 these methods is greatly to be preferred on account of accuracy, but 

 the others are much less tedious and for that reason are usually con- 

 sidered to be more practicable. 



EXAMINATION OF WINE. 



The ordinarv determinations to be made in the examination of wine 

 are specific gravity, alcohol, glycerol, extract, ash, total acids, vola- 

 tile acids, fixed acids, polarization, potassium sulphate, sodium chloride, 

 total sulphurous acid, free sulphurous acid, tannin, and phosphoric acid. 

 The glyceroi-alcohol ratio, ash-extract ratio, and "undetermined 

 extract " should also be calculated. It is believed to be much more 

 convenient and satisfactory to state all results in terms of grams per 

 100 cc than in terms of percentage by weight. The calculation is thus 

 materially simplified, and at the same time the results do not vary 

 greatly from those expressed in terms of percentage by weight. 



