178 



GIBBS. 



The minus reading gradually returns to zero as the sugars disappear by 

 fermentation. When sap is collected in alcohol, no fermentation of any kind 

 results and an albuminous precipitate gradually settles out. Since this pre- 

 cipitate was supposed to contain the enzyme causing the inversion, a portion 

 was filtered from a 50 per cent alcohol solution of sap, washed and placed in a 

 pure sugar solution under toluene. 



Initial rotation 

 After 24 hours 

 After 20 days 



+9.7 

 +9.7 

 +9.0 



This precipitate is inactive, while that which forms spontaneously in the sap 

 is active. 



Alcohol fermentation. — A comparatively small yield of alcohol results 

 from the spontaneous fermentation of the sap of the buri palm. 



Fresh sap containing 10.5 per cent sucrose was allowed to stand until 

 the latter had decreased to 1 per cent, and then the alcohol was deter- 

 mined at intervals. 



Date. 



Time in 

 hours. 



Alcohol 



by 

 volume. 



November 9, 1910. 

 November 10, 1910. 

 November U , 1910. 

 November 15, 1910. 



24 



72 



168 



2.0 

 2.0 

 1.65 

 .65 



Other samples of sap yielded about 3 per cent of alcohol. 



Acetic acid fermentation. — Fresh sap collected at 11.30 in the morning 

 of August 19, 1910, being neutral at the start, showed the following 

 acid fermentation: 



Time interval. 



Acidity. 



cc. of tenth 

 normal sodi- 

 um hydrox- 

 ide required 

 to neutralize 

 100 cc. 



Calculated 

 as acetic. 



hour 



Neutral or 

 slightJy 

 alkaline. 

 Neutral or 

 slightly 

 acid. 



4 



5 



48 



54 



315 





2 hours 





4 hours 



0.024 

 .030 

 .288 

 .324 



1.890 



5 hours 



24 hours 



26 hours . _ 



22 days „ . 





