42 



INTRODUCTION. 



Fig. 44. 



Fig. 45. 



Fig. 46. 



Potato Starch. 

 a Normal particle, b Irregular do. c d Particles 

 with two hila. efg Particles broken by pressure 

 and water. 



other granulated, which is either white or brown. The first is whitish, with 

 a somewhat reddish tint; it has a faint odour. Under the microscope it is 

 found to consist of oval or ovate particles, many of which appear as if trun- 

 cated, so as to be more or less mullar-shaped. They are usually more or 

 less broken, and most of them have an irregular or tuberculated surface. 

 The hilum, when perfect, is circular, and cracks either with a simple slit, or 

 in a cruciform or stellate manner. The surface is annulated, but less distinct 

 than in potato starch. The granular sago consists of the same kind of 

 particles, but larger, more broken, and less regular in their form. Sago is 

 obtained from several species of Sagas. 



Tapioca. Is in small irregular lumps or grains, partially soluble in cold 

 water. When examined under the microscope, they 

 are found to consist of entire and broken particles ; the 

 first of which appear circular or mullar-shaped, with a 

 ^distinct and marked hilum. Sometimes the mullar- 

 formed ones have a contracted base ; at others, instead 

 of the flat end, there are two faces meeting at an obtuse 

 angle. The hilum is surrounded by rings and cracks 

 in a stellate form. 



Suga.r. There are several kinds of sugar, some capable of undergoing 

 fermentation, the others not. To the first class belong cane, grape, or 

 starch sugar, and to the latter liquorice sugar, mannite, &c. 



Cane Sugar. This is found principally in the sugar cane, but also exists in 

 some quantity in the root of the beet, in the sap of the maple, &c. It crys- 

 tallizes in oblique rhombic prisms, and requires one-third its weight of cold 

 water to dissolve it. When acted on by dilute acids, it is converted into 

 grape sugar. Its composition is C 13 H 11 O 11 . 



Grape Sugar. This exists in grapes, honey, figs, &c, and can also be 

 obtained by the action of dilute sulphuric acid on starch, lignin, &c, and 

 even by the same means from cane sugar. Much of it exists in molasses. It 

 is less soluble than cane sugar. Its composition is C lf2 H 1 * O 14 . 



Mannite. Forms the greater portion of pure manna, and is also found in 

 the celery and other plants. It is not capable of fermentation. Its composi- 

 tion is C 8 W O 8 . 



Liquorice Sugar. This is very soluble in water, but cannot be made to 

 crystallize ; with acids it forms compounds which are very sparingly soluble. 

 It is incapable of fermentation. 



Gum. This substance exudes in a fluid form from many plants, and be- 

 comes hard by an evaporation of its watery particles. When pure, it is co- 



Tapioca. 



