44 A FEW CHEMICAL CHANGES 



Liebig and Wohler prepared amygdalic acid or glucoman- 

 delic acid, C 9 H O from amygdalin, by boiling it with 



baryta water, the change taking place i'n this way: 



This acid is a white crystalline substance which readily 

 forms amorphous salts. 



It is probable that the change taking place with Fehling's 

 solution is one similar to this. The action of the potassium 

 hydroxide is to form amygdalic acid and ammonia., 'and at the 

 same time a'n insoluble salt of the former is formed with the 

 copper, which is held in solution by the sodium and potassium 

 tartrate in the Fehling's solution. 



The decomposition of amygdalin by Fehling's solution does 

 not take place unless the solution is boiled. However, if the 

 solution of amygdalin is boiled with potassium hydroxide, 

 cooled, and then a few drops of Fehling's solution added to it 

 the bluish precipitate is formed. 



A quantity of this precipitate was formed and washed free 

 from amygdalin and Fehling's solution. When some of it was 

 heated on a piece of platinum foil it charred, showing that it 

 contained organic matter, and a greyish residue containing a 

 carbonate and copper, but no sodium nor potassium was left 

 behind, 



From the foregoing facts it would seem that, on adding 

 Fehling's solution to a solution of amygdalin and boiling, we 

 have ,a change taking place like that observed bv Liebig and 

 Yvohler, resulting in the break down of the amygdalin. As a 

 result of this decomposition the nitrogen of the amygdalin is 

 changed to ammonia, and a bluish white precipitate, which is 

 probably a copper salt of amygdalic acid, is formed. It is 

 believed that the evolution of .ammonia and the formation of the 

 precipitate noted above, might be used for the detection of 

 amygdalin. When the amygdalin has been under the influence 

 of radium for a time, it is found this change is more complete. 



