CHAPTER XXV 



The Determination of Cane Sugar and the Assay of 

 Sugar House Products 



The routine analyses necessary for the control ot a cane sugar-house com- 

 prise the determinations of : — Specific Gravity, Soluble Solids, Water, 

 Polarization, Sucrose, Reducing Sugars, Fibre, Ash, Acidity and Alkalinit}'. 

 Other specialized determinations are mentioned separately. The bearing 

 of these determinations on the control and other inter-relations is discussed 

 in this chapter, together with the means adopted for their execution. 



Specific Gravity, Degree Brix, Soluble Solids, etc. — The specific gravity, 

 or density, of a material is used for determining the solids in solution referred 

 to a sucrose-gravity basis. Thus a i6 per cent, solution of sucrose in water, as 

 determined at 20° C. and compared with water at 4° C. as unity is of specific 

 gravity 1-06346. A sugar-house material of this specific gravity is said to 

 contain 16 -o per cent, soluble solids, or to be of 16 -o degrees Brix.* 



Other synonymous terms are total solids and apparent dry substance. 

 The writer has used the term gravity solids, as thereby confusion as to the 

 basis of reference is avoided. 



In place of deducing the apparent dry substance from the specific gravity, 

 the refractive index has also been used. Thus the refractive index at 28° C. 

 compared with water at 28° C. of a 16 per cent, solution of sugar is 1-3562, 

 and a sugar-house material with this refractive index is said to have 16 

 per cent, apparent dry substance, or total solids. The term used by the writer 

 is refractive solids, and the expression optical solids is also in use. The intro- 

 duction of this method is due to Main.^ The real dry substance in solution 

 is determined by drying to constant weight. The results of determinations 

 made in this way are referred to as total solids, true total solids, or dry sub- 

 stance. The term used by the writer is absolute solids. 



The relation between the three bases of comparison is as under : — 



Gravity solids > Refractive solids > Absolute solids, and the difference 

 is found to increase with the quantity of non-sugar, particularly salts in 

 solution. Reducing sugars have almost the same solution factor as cane 

 sugar, and the difference is not great for other organic bodies which occur in 

 sugar-house materials. 



* Brix is the name of the German chemist whose determinations of the relation between sugar per cent, and 

 specific gravity of solutions are generally accepted. Previously the degree Balling, named after an Austrian chemist, 

 was used. The principle involved is the same and the difierences are very small. In France the degree Vivien 

 is used. This gives, referred to a sucrose basis, the grams soluble solids per lOo c.c. of material. Hence Degrees 

 Brix X Specific gravity = Degrees Vivien. 



490 



