288 SORGHUM. 



As the character and composition varies so greatly, as to the im- 

 purities of the juice, it naturally follows that the methods which have 

 been suggested, and which have been adopted in practice, have differed 

 as widely. That there yet remains great room for improvement, none 

 will more readily admit than those fully conversant with the advan- 

 tages and defects of the present methods. In the hope that the in- 

 ventive faculties of those who are engaged in this new sorghum sugar 

 industry may be stimulated and directed, it will be the aim of this 

 chapter, not only to describe the methods of defecation in use or sug- 

 gested, but also, so far as is possible, to consider the principles in- 

 volved in the several methods. 



Mechanical Impurities of Juice — Nature of, and Methods of Removal. 



The mechanical impurities of the juice of sorghum are fragments 

 of the cane, dirt, wax, and starch. 



We have already seen how readily fermentation is excited in a sam- 

 ple of juice by the presence of the bagasse with the formation of what 

 appears to be the so-called gum, which has proved so troublesome in 

 the extraction of sugar from syrups. The most careful experiments 

 "with freshly expressed juices, have invariably failed to reveal even a 

 trace of this gum; so that its subsequent presence in the products proves 

 conclusively that it must be the result of the method of manufacture. 

 Owing to the trouble it produces in purging the sugar^ and the loss of 

 sugar it causes, the source whence it is derived, and the method by 

 which it is produced, should be careftdly investigated, so that the 

 source may be removed, or the method of its production avoided or 

 modified. 



Nearly every sample of sorghum juice will reveal the presence of 

 starch grains, wdiicli will give their characteristic color with iodine so- 

 lution ; and we have already referred to the presence of the starch in 

 the slices of cane when examined under the microscope. In the crush- 

 ing of the cane these grains are mechanically carried along with the 

 juice. 



The presence of this starch, although the actual amount is small, is 

 beyond question highly detrimental to the juice, aud does not appear 

 to have received the attention it demands. Its removal must be ac- 

 complished at the outset, if at all, since the heat employed in the ordi- 

 nary methods of defecation would speedily convert it into a form ren- 

 dering its removal, by mechanical means at least, quite impossible. 

 The size of these starch grains is such as to preclude their separation 

 by ordinary filtration, such as would readily suffice for the removal of 

 the principal mechanical impurities. 



