76 ELEMENTS OF BOTANY. 



103. Experiment 22. Testing for Grape SMpror. 7— Heat to 

 ■boiling in a test-tube or a, small beaker some weak syrup of grape sugar 

 or some honey, much diluted with water. Add Fehling's solution, a fe-vr 

 drops at a time, until a decided orange color appears. Repeat the test 

 with the water in which some slices of onion have been boiled, filterinf 

 the water through a paper filter and heating again to boiling before add 

 ing the test solution.! 



Does the onion contain grape sugar ? 



1 The deposit will in this case, even if orange at first, finally become black, prol 

 ably owing to the presence of sulphur in the onion. 



