432 CHAPTER XXI 



The largest constituent present in the ash of a cane sugar is potash. 

 The other bases present are lime and magnesia, with traces of iron. The 

 acids with which these are combined are organic acids (appearing in the ash as 

 carbonate) sulphuric, silicic, and phosphoric. Chlorides are also very often 

 present. From inspection of a large number of analyses the following may 

 be given as the limits in which these occur : — 



Potash 40 to 50 per cent. ; lime, 3 to 10 per cent. ; magnesia, i to 5 per 

 cent. ; soda, o to i per cent. ; carbonic acid, 5 to 20 per cent. ; sulphuric 

 acid, 4 to 15 per cent. ; silicic acid, i to 5 per cent. ; phosphoric acid, o to 2 

 per cent. ; chlorine, 5 to 20 per cent. 



The actual composition of the ash wiU be influenced by conditions of 

 soil, manuring and variety and by the maturity at harvesting. 



Of the organic non-sugar, but little is known ; as calculated from the 

 composition of molasses a typicEil 96 test sugar will contain from 0-05 to 

 o • 2 per cent, of gums (or alcoholic precipitate) : from o • 01 to • 05 per cent, of 

 nitrogen, much of which is present as amide, very great variation being ob- 

 served as between different analyses. Calculated from carbonic acid in 

 the ash the organic acids may be estimated as from 0-05 to 0-2 per cent. 

 In the balance, which is more than half of the organic non-sugar, will be found 

 caramel, all the bodies of unknown constitution and varying quantities of 

 suspended matter derived from cane fibre. 



The Physical Characteristics of Raw Sugar, — ^The physical characteristics 

 of a raw sugar that have influence in determining its value are the amount 

 of insoluble matter, the size and the regularity of the grain, the hardness of 

 the grain, and the nucleus of the crystal. The quantity of suspended matter 

 depends on the efficiency of the defecation process, and what insoluble matter 

 is present is due to suspended particles carried through the processes. It 

 consists very largely of particles of cane fibre. The quantity present in raw 

 sugars of 96 test made by a process of defecation without bulk filtration 

 win vary between the limit of o- 02 to 0-2 per cent., with an average of about 

 0*1 per cent. 



The size of the grain varies from a maximum of over 2 mm. side to a 

 minimmn of less than 0-5 m.m., but in any one sample grains of all sizes 

 will be found with a very different distribution of crystals classed as large, 

 medium and small. 



The hardness of a sugar is doubtless a misnomer, since it is probable 

 that all crystals as individuals are equally hard. What is indicated by the 

 term is rather friability. A sugar composed of small crystals cemented 

 together by molasses will be easily crushed between the fingers and will 

 appear soft to the touch, while one consisting of large individual crystals 

 will appear hard under a similar test. 



By the nucleus of the crystal is indicated a difference in the method used 

 to form grain. Generally, the grain is formed directly from the syrup, but 

 in other cases low grade sugars of small grain are used as seed. In the latter 

 case an impure material is contained in the interior of the crystal. 



The colour of the sugar refers to both the colour of the dry sugar and to 

 the colour in solution. It is evident that the colour wiU be correlated to the 

 quantity of molasses adhering to the crystal. What colour is actually 

 present may be due to the natural colouring matter of the cane, or may have 

 been developed in the process of manufacture by the action of heat-giving 

 caramel or by the combined action of heat and lime on the reducing sugars. 



