RAW SUGAR 437 



7. If a cooling tower or distillery is operated, place these to leeward of 

 the factory so as to avoid air-borne infection of the sugars and juice. 



8. Keep all containers and the whole factory as clean as possible, pre- 

 venting not only infection but also the evolution of a virulent strain of 

 organisms, since Owen^^ has shown that this occurs when the forms respon- 

 sible have a continuous habitat. Aseptic conditions should be particularly 

 maintained at and near the centrifugals, since Kopeloff^® has shown that 

 generally the floors and immediate surroundings are foci of infection, 

 whence the organisms can be drawn into the centrifugal basket b^^ a current 

 of air, as was first suggested by Shorey.' 



9. If it were possible to do so, cold storage below 20° C. would eliminate 

 destruction due to micro-organisms. Conversely in Java, when during 

 the Great War large quantities of sugar were stored, the warehouses were 

 kept as hot as possible, %vith the object of drying the sugars and concentrating 

 the film of molasses. 



In the great majority of cases where sugars are attacked by micro- 

 organisms a fall in polarization occurs. Exceptionally, instances are found 

 where a rise in polarization results. This phenomenon is due to a selective 

 action of the micro-organisms towards reducing sugars, the cane sugar itself 

 not being attacked. This observation was first made by Watts and Tem- 

 pany,^^ and has also been observed by Deerr and Norris,^^ and by Browne.^' 

 The last-named has suggested that the occasional appearance of a sugar 

 with a sucrose content lower than the polarization may be due to the destruc- 

 tion of the fructose due to a selective action of certain micro-organisms. 



The Valuation of Raw Sugars. — In the American market raw sugars are 

 valued on a polarimeter test alone, the basis being a direct polarization of 96°. 

 The value to the refiner is, however, also governed b}^ the phj'sical char- 

 acteristics and by the purity, as is discussed in other sections. In other 

 countries other methods of valuation are in use, and include special methods 

 of analysis, which are briefly indicated in this section. 



In 1863 Monnier-2 introduced a method for the valuation of sugars based 

 on the supposition that the quantity of sugar retained in the molasses was 

 proportional to the ash content of the sugars. In his method a sugar was 

 estimated to \deld the polarization less five times the ash content, and in- 

 cluded in this formula are all the mechanical and other sources of loss. 

 This formula was accepted as a basis of sale between refiners and producers. 

 At various times other formulae have been in use. Thus one due to 

 Pagnoul-3 deducted four times the ash, twice the reducing sugars and 

 allowed a manufacturing loss of 1-5 per cent. Another formula deducted 

 five times the ash and the reducing sugars. Scheibler-^ proposed to obtain 

 the rendement by deducting four times the organic non-sugar, but this 

 proposal was never adopted. 



Stammer and Weiler^^ were the first to propose the use of the total non- 

 sugar, and at present in Germany sugars are valued on the basis of polariza- 

 tion less 2*25 times the non-sugar. It is evident that this is the same as 

 a sale on a purity basis with a purity in the molasses of i -^ (2-25 +1) or 

 30-8, and neglects the specific effect of the various substances present in 

 the non-sugar. These formulae should be read in connection with Geerligs' 

 theory of molasses formation {see Chapter XXII). The purchase of sugars 

 on a purity basis is discussed in a subsequent section. 



The second method determines the actual crystal content of a raw sugar. 



