41<^* AClDiTV OF WINli. 



SO that there were 12 different experiments for each yeast con- 

 centration. After ten weeks the fermentations were over, and 

 the H(|uids above the lees were quite clear. Each of the 36 

 sami)les of lees, taken one from each of the T,h bottles when the 

 analyses were made, was perfectly ])ure and free from bacteria or 

 Mycodcrma vini. In every case the alcohol and volatile acid 

 were now determined. The original experimental licjuid con- 

 tained o. I per mille volatile acid. Below are given the results for 

 the three yeast concentrations in groups i and 4 {i.e., where 3 and 

 f) gr. alcohol ijer 100 c.s. li(|uid were present at beginniuii' of ex- 

 periments) and for sugar concentrations i, 2 and 3: 



Tst Series. 2nd Series. 3r(l Series. 



1st Group. 

 Alcoliol gr. per 



100 CO 6.,u ''^.4'j 10.4a 6._'[ S.4_' 10.14 6.34 S._'8 lO.S*) 



Volatile acid, gr. 



per litre o.jj o.3(> 0.31 0.35 0.4J 0.54 0.3.' 0.43 0.56 



4141 Group. 

 Alcohol, gr. per 



100 c.c. ('-9^ 8.84 10. (X' (^-My '^■77 10. Sj (i-^c, 9-4- 10. (j() 



V'^olatile acid, gr. 



per litre 0.26 0.31 0.40 O.27 0.31 0.40 0.20 0.3,^ 0.44 



From these data we conclude tiiat : 



(1) Although the dift'erences are not great, it will still be 

 noticed that in all three series, on comparing the corresjxjuding 

 ti^ures of groups i and 4 in each vertical column, the volatile 

 acidity in group 4 is in e\ery case api)reciabl\' lower than in 

 group I. This means that more volatile acid was formed where 

 the initial alcoholic strength of the liquid was lowest. 



(2) The increasing amounts of yeast cells introduced, when 

 Inoculating series i, 2, 3, had no influence on the volatile acid, 

 formed. 



(3) As the sugar concentration in the original exijcrimental 

 liquid rose (columns i, 2, 3 above), so the alcohol and the 

 volatile acid in the fermented li(|uid rose. This is in keeping 

 with general exi)erience. 



In actual cellar ])ractice conclusion (2) ;il)o\c does not hold 

 good. By adding more active yeast cells of a i)ure culture to^ 

 a wine that got stuck, we get a wine with less volatile acid than^ 

 when only a relatively small number of yeast cells is introduced. 

 Here we are not working under sterile conditions ; hence the 

 explanation is that the laruer number <)f yeast cells can keep 

 down the development of acetic and oilier I)acteria, and tints 

 hel]) to keep the volatile acid low. 



New Experiments. 



I. Pcnncntatioiis conducted zvilli Pure Cultures of />ifj'erei!f 

 Yeasts and Different Concentrations of Sugar in the Must. 



A. Experiments with Must of 27.9^ /> a///"*///. —Sterilized 

 must of 22.5"^ j-ialling was eva|)orated on a waterbath till it had 



