108 



inversion in a 30 per cent solution at 100° was 0.0423, and at 110°, 0.0557. 

 Assuming that the impurities in a cane juice raise the boiling point up to even 

 105°, during the four hours, there would only be lost about 0.2 per cent of total 

 sucrose by inversion. Local overheating of the pans, and boiling the juice before 

 it is completely neutralized, will raise this figure somewhat, but it may be safely 

 stated that ordinarily less than 1 per cent of sugar is lost by inversion prior to 

 boiling do\vn in the "caua mayor." 



Sucrose turned in manufacture. — While sugar solutions of moderate concentra- 

 tion may be heated for a long time with little loss, when they are highly concen- 

 trated a much more rapid inversion takes place. Eckleben -^ found that an 85 per 

 cent sugar solution heated in a closed vessel at 120° to 125° was completely 

 inverted in six hours. The "massecuite" from the No. 1 "caua," since it contains 

 as a rule only from 5 to 10 per cent of water, must attain a temperature of 

 from 120° to 130° during the last stages of concentration, and owing to imperfect 

 circulation and conduction of heat in such a thick solution, the temperature of 

 that portion in immediate contact with the sides of the kettle is necessarily 

 much higher. As has been previously explained, only a small percentage of the 

 total inversion occurring here can be determined analytically, since the invert 

 sugar formed is rapidly decomposed at this high temperature. 



Probably the largest losses incurred in the process of manufacture take place 

 in the "caua mayor" during the last fifteen or twenty minutes' boiling of each 

 "cocida," and the longer it is necessary to keep the "massecuite" in this pan 

 the greater becomes the loss. A "massecuite" of high purity can be concentrated 

 rapidly without so much danger of sticking to the pan and burning, since sucrose 

 is more soluble in the water of such a "massecuite" than of one containing more 

 impurities ^ consequently it remains in solution longer and boils more uniformly. 



An impure sirup, during the first half of its evaporation in the final kettle, 

 may appear as light colored as any other, but, as it becomes thicker and hotter, 

 decomposition of the invert sugar begins, giving rise to dark-colored products, 

 some of which, probably, being of an acid nature, cause still more inversion of 

 sucrose. Sometimes a "cocida" will boil along very smoothly for a time, then 

 suddenly turn dark and begin to stick to the pan, at times bumping with suffi- 

 cient violence to scatter hot "massecuite" clear out of the pan. In such cases 

 any attempt at further concentration is generally useless, as the sugar decom- 

 poses rapidly, often giving off smoke and acrid vapors, and it can never be made 

 to crystallize properly. Boiling too much "massecuite" at one cooking, poorly 

 arranged "cauas," ineflicient firing, poor fuel, in fact anything which prolongs the 

 stay of the "massecuite" in the first kettle, increases the loss by burning. This 

 fact is well appreciated by the planters in general, who say that it is very difficult 

 to produce good sugar in rainy weather, even from excellent cane, since the 

 bagasse can not be sufficiently dried to give a hot fire. 



Mechanical losses. — These are, of course, impossible to determine separately. 

 They will be estimated together with those due to burning in manufacture in the 

 calculation of the percentage yield from the cane, which is given in a subsequent 

 portion of this paper. 



='»Z. Ver. Zuckerind. 40, 817. 



=»Geerlig3, Cane Sugar and its Manufacture. Manchester (1909), 225. 



