40;^ ACIDTTN OF WINE. 



months. The following extract from the tignres given for th^ 

 analyses made oai the 25th February, 191 1 (fermentation of 

 grape-juice), will show the great differences between the amount^ 

 of volatile acid formed bv the different yeasts : 



In most cases a strong new growth df yeast cells was ob- 

 served overlying the lees as a flocculent layer, which had taken 

 place after the fermentation was over. Osterwalder ascribes the 

 abnormal amounts of volatile acid formed to this pronounced 

 subsequent growth of yeast cells. 



He then commenced a new series of experiments with two of 

 the above yeasts that had formed much volatile acid, namely. 

 Siders 5 (Pendant) and Neuenburg 2 (Pinot), and with two that 

 had formed very little volatile acid,, namely, Chardonnay and 

 Steinberg 3. Half the bottles were closed with perforated corks 

 having concentrated sulphuric acid air-seals, whereby the air was 

 cut off, whilst the other half were closed with plugs of cotton- 

 wool having a piece of paper tied over them, whereby the air was 

 given fairly free access. The bottles were inoculated on the 12th 

 i\pril. 191 1, and kept in a cupboard at summer air temperature. 

 The wines were analyzed towards the end of May, 191 1, when 

 the fermentations were over. The original must contained per 

 litre: 162.24 gr. invert, sugar, 2.96 per cent, total acid (as tar- 

 taric acid), 0.20 per mille volatile acid (as acetic acid). Fur- 

 ther analyses were made in August and October respectively. 

 The following are some of the results obtaiaied : 



(i) Where the air was excluded (concentrated sulphuric acid 

 air-seal), the volatile acidity in the case oif the four yeasts 

 above mentioned was as below : 



Date of Siders 5 Neuenburg Chardonnay Steinber<i 



Analysis. (Pendant). 2 (Pinot). i 3 



Per mille. Per mille. Per mille. Per mille. 

 30 May— 14 June 0.36 0.66 0.48 0.67 



30/5/1 r 30/.SA1 14/6/1T .3/.S/11 

 8 August, 191 1 0.66 0.56 0.60 0.67 



17 Octoiber, 1911 0.60 0.56 0.70 0.64 



On the whole the volatile acidities here found are not high, 

 and on the 17th October they did not differ very materially. The 

 first two even show lower values than the last two. 



