2 3^ CAPE WINE-LEVURES. 



But ioo ccm. alcohol are formed out of 156.5 grs. sugar if 



100% of the sugar is decomposed. 



H x X 258 



Hence — - — ,= iz(y z. 



157.0 J D 



whence x = 94.8%. 



In case of the wine with 16.37 volume per cent, alcohol this 

 becomes 99.3%. Reckoning 170 grs. sugar per 10 volume per 

 cent, alcohol means that only 92% sugar gave alcohol. This 

 makes no allowance for alcohol lost by evaporation. 



4. Cellar Experiments with these Levures. 

 1. Pontac. Vintage 191 1. 



Pressed on 8th February, 191 1. 



Composition of must : Sugar = 27.7 Balling. 



Total acidity = 9.7% as Tartaric acid. 



The crushed grapes minus their stalks were immediately 

 inoculated with a pure culture of the levure PB2. the proportion 

 being about 1.200 or }%. Fermentation started very soon, since 

 the must had a temperature of 26 C. atthe very start. During 

 48 hours the fermentation was conducted in an open cement 

 tank, the cake that forms on the fermenting must being pressed 

 under about every two hours. Then the must was drawn off 

 into 4 hogsheads — the press-must being added to the rest. When 

 the temperature had got to 35 ° C. in the hogsheads, 100 grs. of 

 potassium metabisulphite was added to each of them. This so 

 far checked the fermentation that the temperature did not rise 

 above 35° C. On the 23rd February (15 days after the grapes 

 had been crushed) the young wine was racked over into a 

 stukvat (under 2 leaguers capacity). On the 15th March the 

 wine was fairly bright, and just a little sweetish. It was then 

 racked into hogsheads, where a slight fermentation set in, and 

 the remaining sugar fermented out. 



An analysis made on the 27th April, 191 1, gave the following 

 results : — 



Alcohol = 15.34% by volume. 



Total Acidity = 8.75 per mille as Tartaric acid. 



Volatile acids = 0.75 per mille as Acetic acid. 



The wine was again analysed about the 20th November, 

 191 1. and then gave the following results: — 

 Specific Gravity at 15 C. . . 3.9982. 



Alcohol 15.7 volume per cent. 



Extract 4.6 grs. per 100 ccm. 



Ash 0.4820 grs. per 100 ccm. 



Sugar O.05 grs. per 100 ccm. 



Total Acidity 7.95 per mille as Tartaric acid. 



Volatile acids 0.85 per mille as Acetic acid. 



Glycerine (on 22/11/11) 1.33 grs. per 100 ccm. 



Alcohol: glycerine .. — 100:10.6. 



