MANUFACTURE OF SUGAR. 427 



13 drawn oQ' clear from the defecating kettle, not a particle of scum is found in 

 the subsequent operations. 



The imperfect defecation in the Colonies is the cause why the brown sugars 

 made there do not dissolve clean, thouijh their color may be good. This is an 

 obstacle* to the direct consumption of those sugars, which must be removed. 



Kettles having vermicular or gridiron pipes at the bottom have been used for 

 defecation ; such kettles do not answer well, the pipes rendering it dilhcult to 

 get rid of the scum and to clean the kettles, which should be done after each 

 strike. 



The importance of the process of defecation being well understood, it will be 

 seen hovv^ little notion of sugar-making those persons have who propose to do 

 away with it. 



Filtration through Animal Charcoal in Grains. — Employment of Large Filters. 



The filtration through animal charcoal is a process which is not analogous to 

 the lillralion of water through sand. Animal charcoal acts chemically on the 

 sugared liquid : it takes hold, as we have already observed, of that excess of lime 

 wliich is necessary for a good defecation, but whicii becomes hurtful in the after- 

 boiling ; it absorbs the vegetable matter, wliich, while it darkens the color of the 

 syrup, favors the decomposition of crystalizable sugar. Animal charcoal, there- 

 fore, acts by abstracting substances Avhich are in combination with the juice, and 

 not by arresting, as would a strainer, substances in simple siispcnsion. 



It is by not taking into account this dill'erence, real as it is, betAveen the proper 

 action of animal charcoal and that of any mere filter-serving substance, that many 

 persons have taken up the erroneous impression that animal charcoal might be 

 dispensed with by filtering through sand or any other inert substance. 



Filtration through animal charcoal is one of the most important points in the 

 manufacture of sugar — not so much, as is generally supposed, in regard to the 

 improvement of quality, as to increase of quantity ; for upon the purity of the 

 juice depends the amount of crystalization. There are manufacturers of beet- 

 root sugar that employ 200 kilogrammes! of animal charcoal for 100 kilogrammes 

 of sugar obtained. The expense is small, considering the facility of revivification. 



From observations made by us during some years past, we have satisfied our- 

 selves that it is highly important tiiat the juice or syrup should remain a long 

 time in contact with the charcoal. Far from being rapid, the filtration should 

 be very slow. This consideration has induced us to substitute, in place of the 

 Dumont filters, other filters of a different shape and of greater capacity. The 

 smallest biters should now hold 1,200 kilogrammes of charcoal. We have had 

 some put up in beet-root sugar manufactories which hold as much as 3,000 kilo- 

 grammes. 



Although the filters employed should be of great capacity, their size does not 

 preclude the use of any quantity of animal charcoal less than the full measure 

 of the filter, even so little as 10 or 12 per cent, of that amount ; but then the 

 juice must remain longer in contact with it. 



From the importance Avhich, it is seen, should be attached to the chemical 

 processes of the manufacture of sugar, no planter would, from motives of econ- 

 omy, be disposed to dispense, in such a system as that described in our work, 

 either with the double-bottom defecating kettles, or with the large size filters. 



Planters should bear in mind that the manufacture of beet-root sugar has be- 

 come possible only since the application of animal charcoal in grains. 



Processes of Evaporation. 



If, for a number of years past, manufacturers agree in regard to the nature 

 of the chemical processes to be employed in the manufacture of beet-root sugar, 

 except as to some changes in the manipulation of those processes, the same 

 agreement has not existed in regard to the evaporative processes. 



For twenty years past, a great number of systems of apparatus have been 



* Note by Translator.— This does not apply so stionijl.v lo tin; Louisiana brown sugars, which, although 

 ♦hey leave a sediment when dissolved, are cleaner and better flavored than the generality of West India 

 sugars. Oui suyHi ia iimde in thi: lull and vvimor. when wc are not troubled with Hies and other insccta, 

 and, having a weaker juice to operate on. are oblieed to use more care and cleanliness. Indeed, the adapt- 

 ation of our sugars for consumptiun. in tlieir unrefined state, will probably have a tendency to limit the re- 

 sort to improved but expensive processes. 



t 1 kilo2ramme=2'30 lbs. avoirdupois. 

 (859) 



