362 SORGHUM. 



unfavorable showing, there are so many advantages to result from the 

 use of cold in concentration, that it is well worth careful investigation, 

 and it is scarcely improbable that, through improved appliances, such a 

 process maybe made practical. The fact that crystallization is a 

 means of purification, owing to the crystal during its growth excluding 

 all foreign substances, has been referred to, page 326. 



The formation of ice, which is simply the crystallization of water, 

 is not an e:sception to this rule. The concentration of cider and of 

 vinegar by the freezing of a portion of w'ater are familiar examples. 

 This method of concentration has been extensively used in the preparation 

 of salt from sea water in Northern Russia, shallow pits being dug upon 

 the shorp, into which the sea water is admitted and allowed to freeze, 

 the ice which forms being nearly pure water. The unfrozen portion is 

 thus concentrated to such a degree as to make furtlier concentration by 

 heat economical. 



SEPARATIOX OF THE SUGAR FROM MOLASSES. 



After the concentration of the juice has been eflTected, it is neces- 

 sary, if the open pan process has been used, to let the syrup remain in 

 coolers or cystallizing tanks until the sugar has had time to separate in 

 crystals. The time required fcjr the completion of this process depends 

 upon the character of the syrup. In case the relative amount of glu- 

 cose and other impurities is small, and the syrup thin and liquid, a day 

 or two will suffice ; but where the amount of sugar is relatively small, 

 the syrup stiff and viscid, weeks, or even months, are necessary to 

 complete the crystallization. It is found that the slower the crystal- 

 lization the fewer and larger the crystals, and, in some instances, crys- 

 tals over an inch in diameter have been produced. The production 

 of rock candy is a case illustrating this. 



Crystallization is facilitated by keeping it in warm rooms, as the heat 

 renders the syrup more liquid, and gives freedom to the 23articles of 

 sugar. 



Crystallization is more rapid from shallow coolers (6 to 10 inches) 

 than from those of great deptli (2 to 3 feet), but, when rapid, results in 

 a mass of fine crystals difficult to free from the molasses, wJiile the crys- 

 tals from the deeper vessels are larger. If the concentration has been 

 properly conducted, there will always be after crystallization a mass 

 of sugar crystals distributed in the molasses. 



The separation of this molasses is accomplished in a variety of ways. 

 The common muscovado sugar, obtained by boiling in the Jamaica 

 Train or open pan, was drained of its molasses by throwing the mass 

 of sugar and molasses from the coolers into hogsheads, arranged so 



