THE CHEMISTRY OF SAKE BREWING. 



219 



Influence of Mineral Acids and Caustic Potash. 



The flasks which contained increasing quantities of sulphuric 

 acid contained lO cc- of aqueous solution of the enzyme. After 

 standing for 20 hours, neutralising with sodium carbonate and 

 adding 10 cc. of a 0.2 % solution of starch paste the mixture was 

 digested at 40°C for one hour. FeJiling s test showed then : 



I % SO3 destroyed. 



0.1 ,, ,, destroyed. 



0.0 1 ,, active. 



I % KOH destroyed. 



0.1 ,, ,, destroyed, 



o.oi ,, ,, activ^e. 

 In a second experiment carried out in the same wa)- 1 

 obtained the following results : 



0.02 % SO3 active. 



0.04 ,, ,, active. 



0.06 ,, ,, active, but week. 



0.08 



0.02 % KOH active 

 0.04 ,, ,, active. 

 0.06 ,, ,, weakened. 

 0.08 ,,• ,, destroyed. 

 The sulphuric acid at 0.06 % is therefore less noxious than 

 potassa in the same concentration. 



Action of Heat. 



Atkinson has found that at above 55°C. the activity of the 

 glucace rapidly diminishes and that between 60 and ycPC this 

 activity is completely destroyed. But it seemed to me of interest 

 also to determine exactly this point with the pure cnzyuie solution 

 as the experiments of /Itkinson were simply made with an 

 aqueous extract of ^(yV which had an acid reaction, that may have 

 had an injurious influence. He observed that this extract turns 

 very turbid upon heating to 6o-70°C. which was due to the presence 

 of coagulable albumin. I did not observe this phenomenon with 

 the solution of the enz)'me wdiich I had prejiared from the koji 



