SORGIWM. 



705 



back the scum for removal, while th'.< dear 

 syrup passes on underneath. Tho siuv 



<.f impurities, already referred to. arc, 



lactorily brought up and rc- 



':; the purification being completed by 



llu- rising of the lighter adhesive scum in the- 



lions, \\ here ebullition is not maintained. 



Tho concentration is completed in separate 



Cook's evaporator is also a long rectangular 

 mailer sixes at least of which are 

 usually mounted with the furnace on rock- 

 ' that, hy giving to the pan more or less 

 inclination, the advance of the juice can be 

 oil her quickened or retarded, in order, while 

 admitting it in a constant stream, to deliver the 

 product always at the required degree of con- 

 centration for syrup, or, as may be, for granula- 

 tion. The passage of the juice, however, is 

 prolonged, by means of a series of ledges run- 

 ning out from the two sides alternately, and 

 each nearly to the side opposite, so that nu- 

 merous transverse sections are formed, but in 

 reality constituting a single tortuous channel 

 from the inlet to the outlet extremity of the 

 pan ; while, the sides of the latter projecting 

 beyond the width of the furnace, a tumultuous 

 boiling is secured along the middle of the pan, 

 and the parts of the current of juice at the sides 

 being meantime quiet, the scum is thrown upon 

 and conveniently removed from these the dif- 

 ferent forms of impurities appearing in succes- 

 sion, and the "cane gum" being very thor- 

 oughly " precipitated " (Mr. Cook states) in the 

 last sections. To this last circumstance, indeed, 

 Mr. Cook attributes in good degree his success 

 in obtaining a syrup capable of granulating 

 well. 



Mr. J. II. Uartwell, of Indiana, constructs his 

 furnace with direct and return flues, alongside, 

 and by dividing his pan, one-half longitudinally 

 and the other transversely, by partitions, causes 

 the juice to take a serpentine course to the 

 point of its exit as syrup. Mr. J. C. McKee, of 

 Illinois, has patented an evaporator essentially 

 in form of a helical inclined channel, receiving 

 the liquid to be evaporated in its middle and 

 highest part, and discharging below, so that in 

 it> passage the liquid is spread in a thin sheet 

 over a large heated surface ; while its admission 

 is regulated to suit the heat and the concentra- 

 tion desired. It should be added that "port- 

 able " evaporators, that is, such as with the 

 furnace and other appliances are mounted on 

 wheels, are also in use. 



The density a syrup will have when cold is 

 conveniently approximated by use of the com- 

 mon taccharometer, an instrument which, as 

 well as the thermometer, should first have been 

 carefully verified. Still, a correct judgment 

 from the indications afforded by these instru- 

 ments will require some practice; as is true 

 also of the common " signs " of a proper con- 

 centration, as found in the appearance of a 

 syrup, its smell, the sound made in boiling, the 

 behavior of a drop between the thumb and fin- 

 VOL. vi. 45 A 



ger, etc. Finished syrun should be speedily 

 cooled to at h-ist 175 (Clough) ; thix, with tho 

 continuous process, ! ted by a broad, 



shallow conductor from the panto the tank or 

 barrel, and, where the finishing is in "strikes," 

 by transferring each of these into a long box, 

 ! on pivots by a lever, and having cross- 

 bars within to agitate and let air into the mass. 



filtering and Management of Syrupt. For 

 the making of the best syrup, not less than of 

 sugar, a very thorough filtering of the liquor is 

 essential ; and this, practised at least once with 

 the syrup, may, with great advantage, in order 

 to remove at first the grosser impurities, be be- 

 gun with the juice. It is not uncommon to 

 strain the raw juice through a sieve, or through 

 clean straw ; but as the running either of 

 juice so treated, or of the syrup from it, through 

 bone-black filters, still rapidly clogs the latter 

 and renders them inoperative, Mr. Clough ad- 

 vises to fit into a tight cask (some inches up) a 

 false perforated bottom, fill in upon this clean 

 straw, and then by a tube from an el 

 reservoir introduce the juice underneath, the 

 pressure causing it to be filtered upward : the 

 suspended matters are thus very effectually de- 

 tained, and the medium is not soon clogged. 



Bone-black filters, however, can alone be 

 relied on to filter the syrup in a manner nearly 

 or quite perfect. Their use may be preceded by 

 that of the double or folded bag-filters; but 

 these, usually foul speedily. The bone-filters 

 maybe of moderate size four feet diameter to 

 about seven feet high : over a false raised bot- 

 tom a blanket or rug is spread, the coal then 

 filled in, leaving a depression a few inches in 

 depth at top, and a second rug laid over alL 

 The syrup, which should not mark more than 

 20 B., is then run on in a small stream, and, 

 when the case is filled, the discharge faucet be- 

 low opened. The first parts escaping, if not 

 quite pure, should be returned, perhaps allow- 

 ing the whole to rest for an hour, when the 

 faucet is again opened ; and as soon as the 

 syrup escapes clear, the draw off and supply 

 may be adjusted to each other. "When the fil- 

 ter ceases sufficiently to decolorize the syrup, 

 the supply is exchanged for that of hot water; 

 and the discharge, when it becomes too thin 

 for syrup, may be returned to the pans for re- 

 evaporation, or the more dilute portions per- 

 haps added to materials to be fermented, until, 

 finally, the almost pure water is allowed to run 

 to waste. 



For the modes of treatment of the washed 

 coal, in order to the revivification of its absorb- 

 ent power?, the reader is referred to the article, 

 BONE-BIJLCK. Mr. Hedges doubts the propri- 

 ety of washing the coal alter re-burning, and 

 recommends to apply no more water than is 

 required for quenching it. 



The great impurity of the sorghum juico 

 renders it desirable that this should have I. ecu 

 clarified as thoroughly as possible before pass- 

 ing it through the coal ; as the latter, besides 

 giving a better result, serves without revivify 



