INDUSTRIES DKPENDING ON PLANT PRODUCTS 



1679 



Among other points that have been examined are the influence exerted 

 on the combination of sulphurous acid by i) the nature of the must ; 

 2) the acidity, which at the strength generally used has no effect; 3) the 

 temperature which, while hastening the action, has within the usual limits, 

 i. e. from 15*^ to 250 C, but Uttle effect on the amount combined; 4) the 

 pressure of the atmosphere which has no influence either. A verv' low 

 pressure can remove aU the free sulphur dioxide, but only acts on combined 

 sulphur dioxide if the temperature is considerably raised. A study has 

 also been made of the disappearance in musts of sulphur dioxide due to 

 evaporation and to oxidation into sulphuric acid by exposure to air. 



The action of sulphur dioxide on special musts has been examined. 

 According to experiments carried out by Muller Thurgax and Oster- 

 WALDER (i), must of health}' grape and of grape infected bj^ Botrytis cinerea, 

 to which 0.225 gm. and 0.450 gm. per Htre of sulphur dioxide had been 

 added, gave the following results. 



Amount of sulphur dioxide combined 



Historj- of must 



After I hour 



After 3 days without 

 fermentation 



These experiments were repeated with Botrytis cinerea grown on grape 

 must and on grapes. Some of the results are shewn in Table III. 



Table III. — The cJiemical combination of sulphur dioxide with must 

 of healthy grapes and of grapes infected by Botrytis cinerea. 



Historv of must 



Amount 

 of acid 

 per litre 



Amount 

 of sugar 



per litre 



I Amount of combined 

 sulphur dioxide 



Per litre 

 of must 



mgms. 



Per litre 

 of sugar 



mgms. 



(i) See R. 191 5. No. 738. 



(Ed.) 



