107 



As in the previous test, only a slight inversion can be detected up to the time 

 the juice is ifully limed; here the formation of reducing sugars seems to continue 

 to some extent, even with an alkaline reaction to litmus in "caua" No. 4, but, 

 owing to the destructive effect of the lime, the "glucose" ratio diminishes again 

 from this point on until the final boiling takes place in No. 1, where it is much 

 increased. 



Since reducing sugars are so easily decomposed at the temperatures which 

 must exist during this final boiling, it is impossible to determine just how much 

 inversion does take place at this stage of the process, but it must be considerable in 

 amount, as the proportion of reducing sugar to sucrose is always decidedly larger 

 on leaving than on entering this "caua," and the increase continues even while the 

 hot "massecuite" is being crystallized in the "enfriaderas." The purity of the 

 juice diminishes gradually during the first heating until clarification is nearly 

 complete, when it again increases. The purity of the last two samples, calculated 

 on the percentage of total solids obtained by drying in an oven to nearly constant 

 weight, is naturally higher than that of the previous ones which were figured on 

 degrees Brix; the difference here is less marked than is generally noted in 

 massecuites from modern sugar factories, the reason probably being that low- 

 grade sugars of the open-kettle type always carry a certain percentage of insoluble 

 impurities such as sand, dirt, bits of bagasse, etc., which raise the true total 

 solids of the "massecuite" without affecting its specific gravity, thus counteracting 

 in a measure the high Brix readings caused by salts in solution. 



From the above tests it is clear that, even with the old open-kettle process 

 of sugar boiling, there is comparatively little loss to be feared by inversion while 

 evaporating the juice down to a density of 50° or 60° Brix, preliminary to the 

 real sugar boiling which takes place in "caua" No. 1, provided reasonable care 

 is taken in liming so as to have the juice either neutral, or very slightly alkaline 

 or acid. This is what might be expected theoretically, since this first evaporation, 

 corresponding approximately to that carried on in modern works in the multiple 

 effects, is seldom carried further than a density of 55° Brix, and even at 

 atmospheric pressure the boiling point of a sugar solution of this concentration 

 is not very high. 



Gerlach " determined the boiling point of aqueous sugar solutions as follows : 



For the purpose of calculation, it may be assumed that the juice is heated in 

 "cauas" Nos. 5, 4, 3, and 2 for a period of four hours, and has during that time an 

 average sugar content of 30 per cent. Herzfeld,=* working with very slightly 

 alkaline solutions of pure sucrose, found that in one hour the percentage loss by 



"Z. Ver. Zuckerind. 13, 283. 

 '^ Z. Ver. Zuckerind. 43, 745. 



