127-129] ROOTS 47 



of strong lead acetate solution. Shake up well and allow 

 to stand for quarter of an hour to settle. Whilst it is settling 

 go on with the next experiment. At the end of the quarter 

 of an hour the liquid in the test-tube will have become quite 

 clear, except for a thick deposit of white material at the 

 bottom. Pour off a little of the clear liquid into another 

 test-tube and add caustic potash solution ; a white precipi- 

 tate will be caused. Add more caustic potash until the pre- 

 cipitate is redissolved ; then add a little Fehling's Solution, 

 and boil. A yellow or bright red precipitate will be formed, 

 which shows the presence of sugar. 



* 127. Cane Sugar and Grape Sugar.— The sugar 

 found in swedes and turnips is a different substance from 

 the sugar which we use for sweetening purposes. The former 

 is glucose or grape sugar, the latter is cane sugar. The 

 properties of these two kinds of sugar are best studied by 

 using the pure substances. Dissolve a little cane sugar in 

 water in a test-tube. In another test-tube make a solution 

 of glucose ; to each of these add a little Fehling's Solution 

 and boil. The glucose will give a reddish precipitate, whilst 

 the cane sugar will not. 



* 128. Inversion of Cane Sugar. — Make a solution 

 of cane sugar in a test-tube half full of water ; add a few 

 drops of strong hydrochloric acid and boil well. After 

 boiling add a little potash to neutralise the acid, then a little 

 Fehling's Solution, and boil again. A precipitate will now 

 be formed, showing that the cane sugar has been changed 

 to glucose by boiling with the acid. 



* 129. Albuminoids in Turnip Juice.— One of the 

 properties of albuminoids is that they are rendered insoluble 

 by carbolic acid. Pour a tablespoonful of turnip juice into 

 a beaker and add two drops of strong carbolic acid solution 

 (80 per cent.) Allow the beaker to stand overnight The 

 albuminoids will settle, leaving the liquid clear. 



