BOTANY. 215 



Starch Sugar. 



If starch be boiled for 48 hours in water, holding 

 jfoyth part of its weight of sulphuric acid in solution, 

 it is dissolved and converted into sugar. The sugar 

 thus acquired is heavier than the starch from which 

 it was formed, the sulphuric acid remains unaltered, 

 and no gaseous substance is either absorbed or 

 emitted. 



Starch sugar does not crystallize into prisms like 

 common sugar, the grains assuming the form of 

 spheres like honey. According, to Kirchhoflf, its 

 sweetening power is to that of common as 1 to %%.* 



Sweet Potatoes. 



Frost converts the starch and mucilage of the po- 

 tatoe into sugar. When potatoes that have been 

 frozen are thawed, they become sweet, probably from 

 oxygen having been absorbed. To remedy this, they 

 ought to be thawed out of contact with the air, as 

 under water that has been recently boiled. 



Saccharine Matter. 



There are two perfectly distinct kinds of saccharine 

 matter, white barley-sugar and treacle ; the one 

 crystallizable and transparent, the other highly 

 coloured, and not crystallizable. 



Ardent Spirits. 



No other substance than sugar can be converted 

 by fermentation into ardent spirits, which, whatever 

 be their name, consist almost entirely of these ingre- 

 dients, viz. water, pure spirit or alcohol, and a little 

 oil or resin, which flavours them. 



* This appears doubtful. 



