3Iar. 2, 190S.] Agricultural Gazette of N.S.W. 237 



a warm room. It is this kind of acidity which is really the grape acids whicli 

 Australian grapes for wine-making are deficient in. 



The other acidity is called volatile acidity, and forms during fermentation 

 and after, in more or less quantity, according to the more or less skilled way 

 in which the grape-juice has been fermented and the wine kept. 



This volatile acidity is mainly due to acetic acid, or vinegar acid, and other 

 acids called, in the chemical nomenclature, fatty acids. They are not fixed, 

 but volatile, because if exposed or shaken in the air they volatilise, and their 

 volatilisation is the more rapid the higher the temperature of the environ- 

 ment. The smell of very dilute acetic acid is pungent, not disagreeable, but 

 that of the other fatty acids is pungent and disagreeable at the same time. 



The wines made in hot climates are all susceptible to contain a relatively 

 large proportion of such acids compared to what you would find in wines 

 made in cooler climates, all other conditions being equal. Portuguese, 

 Spanish, Southern French, Calabrian, Sicilian, Dalmatian, Algerian wines 

 that have not been taken special care of during and after fermentation, 

 contain a proportion of volatile acidity beyond the degree tol^^rated by an 

 ordinarily sensitive palate. 



The climate of Albury district must be regarded as a hot one during 

 :summer, and, while little trouble will be found in growing grapps, extra care 

 must be taken to avoid high temperatures in the cellar and vats, or fermentation 

 will take place too violently. 



I have already stated that the alcoholic yeast is an organised and living body, 

 the life of which is much influenced l)y its environment. Too much sugar is 

 a fault in gra2)es if you want to make light wine. Light dry wines should 

 not cont-iin more than from 10 to 12 per cent, of absolute alcohol by volume, 

 to obtain which from 17 to 20-2 per cent, of sugar are required. In Albury 

 disti-ict you get 25 and 30 per cent, and over. Such musts are specially 

 indicated for making swe^t wines of Port and Sherry types, also of Muscats, 

 or for heavy dry wines useful for blending; lighter vintages can, however, 

 supply a Burgundy. Fixed acids are generally deficient, in so far their pro- 

 portion is from .3-5 to 5 parts of must per 1,000, or a little over. Tliose 

 nuists would be better if they contained from 6 to 8 parts per 1,000. 



The operations on musts and wines may be divided in licit and illicit 

 treatments. The correction for the deficiency of acidity by increasing it 

 through the addition of tartaric acid is quite licit, and allowed by the ^Yine 

 Adulteration Act, 1902, in force in this State. Tartaric acid is a natural 

 ingredient of the grape-juice, and its deficiency may be corrected within the 

 limits of what a suitable degree of acidity should have been. Now, to 

 do so, one should Ije able to estimate how much fixed acidity the various 

 kinds of grape-juice naturally contain at every vintage. To make such 

 estimation requires a knowledge of chemistry, and the possession of manipu- 

 lative skill, which is not usually found in vignerons, but I may safely say 

 that, if you increas- the acidity of your nmsts by two parts per thousand, 

 you will keep within safe, limits — that is, you may safely add to the must 

 and .skins of 1 ton of grapes, 2 lb. -t oz. -of tartaric acid. 



