54 



SILK MANUAL, ANt> 



BEKT ROOT. 



(Continued.) 



As soon as the bottom of the evaporating ves- 

 sel in covered with juice, the fire is kindled, and 

 ebullition is produced as speedily as possible, — 

 the juice which c( ntinues to flow from the clarify- 

 ing boiler supplying the loss occasioned by evap- 

 oration. 



When the boiling juice marks 5° or 6'^ ( = 1.036 

 to 1.044) of concentration, a portion of animal 

 charcoal is thrown in, and this is continued, the 

 quantity being gradually increased, till the juice 

 is concentrated to 20° ( = 1.161.) Sixty poimds 

 of charcoal arc used in this manner, for a quan- 

 tity of juice equal to from 422 to 475 gallons. 



After having brought the liquor to the twenti- 

 eth degree of concentration, the boiling is con- 

 tinued till the sirup marks 27 or 28° of the hy- 

 drometer, (=specific gravity of 1.231 to 1.242.) 

 The sirup being mixed with animal charcoal, re- 

 quires to be filtrated. This operation, as it is 

 usually performed, is very tedious, and sometimes 

 becomes injpracticable ; the consistency of the 

 sirup is increased two or three degrees by cooling, 

 and the pores of the filter becoming in a short 

 time, obstructed by the finely divided charcoal, 

 the thickened liquor can no longer pass through 

 them. 



To obviate these inconveniences I place a large 

 willow basket over a boiler: into the basket I put 

 a coarse bag of the same diameter, but about two 

 feet deeper, I pour the thickened sirup into the 

 bag ; for soijie minutes filtration goes on very well, 

 but as the liquor grows thick in consequence of 

 its cooling, filtration slackens and at length stops ; 

 as soon as i perceive this, 1 turn the borders of 

 ihe sack into the basket, and U[)on them place a 

 wooden trencher, which I gradually load with 

 cast iron weights till the necessary pressure is 

 produced ; filtration is by this meaas completed in 

 twe or three hours. 



The charcoal contained in the sack is leaehed 

 with warm water, and afterwards submitted to the 

 Jever f)ress to force from it all the sirup contained 

 in it. The waters used for these loachings dur- 

 ing on« day, are the next day mixed in the clari- 

 fying iboiler with the juices that are then prepar- 

 ed. 



The conversion of the juice into sirup should be 

 done as speedily as possible ; for when evapora- 

 tion is slow the liquid becomes pasty, as part of 

 the sugar is decomposed and passes to the state of 

 molasses, and the difficulty of boiling is increased. 

 It is necfjssary then that evaporation should be 

 carried on with violent boiling, and for this reason 

 the boilers made use of should be broad and shal- 

 low, so as to heat only layers of the liquor, and in 

 order that ebullition may take place at once through 

 the whole mass of the liquid ; <he furnaces like- 



wise should be so built as to heat the boilers 

 equally. The evaporation of 422 gallons should 

 be completed in four hours. 



The operation is known to be good and the 

 juice to have boen well prepared, when ebullition 

 takes place without causing the liquor to swell and 

 blister ; when there appears on the surface only a 

 brownish foam, the bubbles of which disappear 

 immediately upon being pressed with a spoon, and 

 when a dry sound is produced by striking upon 

 the liquor. 



If, on the contrary, there formsa whitish, gluey 

 foam, which does not subside, the ojteration is 

 bad ; evaporation requires a long time and the 

 boiling is difficult. In this case a little butter is, 

 from time to time, thrown upuv the surface to 

 quiet the eflfervescence ; the quantity of animal 

 charcoal is increased, and the fire is checked. All 

 these jjalliatives, however, do not correct the radi- 

 cal fault, and such appearances always presage 

 bad results. 



ON BOILING THE SIRUP. 



The sirups prepared over night are the next day 

 dried to extract the sugar from them. 



Theproducts of two operations upon 6000 beets 

 are mixed together in a boiler, whence they are 

 taken to form four successive dryings or boilings. 

 One fourth part of these sirups is thrown into a 

 round boiler, forty inches in diameter and twenty 

 in dejjth ; under this a fire is kindled; the liquor 

 is made to boil, and the boiling continued till the 

 operation is ended. 



Tiie process is judged to be going on well if the 

 liquor exhibits the following symptoms. 



1. When the sirup breaks short, and the bub- 

 bles upoii returning into it produce a .sensible 

 sound. 



2. When a dry sound, like that produced by 

 striking silk, is returned from the surface of the 

 sirup, when it is struck with a skimmer. 



2. When the bubbles of foam disappear im- 

 mediately upon being pressed with a spoon. The 

 boiling is always perfect when the interior surface 

 of the boiler is foimd, after the operation is ended, 

 to retain no trace of blackness. 



The sirup is known to be bad by the following 

 signs : 



1. When a thick, whitish, gluey foam appears 

 upon the surface of the liquor, 



2. When the liquor swells and foams, and does 

 not subside. 



3. When the escape of puft's of acid steam an- 

 nounces that the boiling substance is burnt. 



The evils are palliated and the boiling termi- 

 nated, 



1. By removing the foam as fast as it forms. 



2. By throwing into the substance small pie- 

 ces of butter. 



