704 



SOKGHUM. 



Evaporation and Concentration of Sorghum , 

 Juice. In course of the earlier experiments, it, 

 soon became evident that the general plan of 

 concentrating the juice of the tropical cane could 

 not in all respects be adopted with that of the 

 sorghum ; but that, with the latter, rapid boil- 

 ing in a shallow stratum, and with the shortest 

 possible exposure to the fire, gave the best re- 

 sults. This discovery led to the general adop- 

 tion of shallow pans, which, whether used 

 singly or in series, would present a large surface 

 to the action of heat. "With these, there are 

 two distinct modes of operating : the Intermit- 

 tent, in which, with one or more pans, the juice 

 is introduced in successive charges, each by 

 itself finished in what is called a "strike" of 

 eyrnp ; and the continuous, in which a small 

 stream of juice is kept flowing into one end of 

 a long pan or series of pans, and the partly or 

 wholly finished syrup is nearly, or quite as con- 

 tinuously drawn off at the other. 



In the intermittent mode, a variety of plans 

 and arrangements are employed, the pans being 

 commonly made in form of a shallow box, with 

 sheet iron, galvanized iron, or copper bottom, 

 and frequently with flaring sides or shores, over 

 which the scum collects. The pans are not 

 uncommonly made with partitions, dividing 

 them into compartments, and into which, by 

 various devices, the juice is successively trans- 

 ferred ; while arrangements of several pans, set 

 at levels descending, and each above commu- 

 nicating with the next by a tube and faucet, are 

 in use ; and also that of auxiliary pans, for set- 

 tling and perhaps straining the juice at the in- 

 tervals of transferring. An apparatus much in 

 use consists of a large defecating pan and two 

 finishing pans of less size, the latter to be alter- 

 nately in use for boiling and being emptied^ and 

 these being perhaps preferably placed over the 

 hottest part of the furnace. 



Mr. Hedges describes his method of concen- 

 trating the juice, with two pans, 4 feet wide, 

 and 15 and 11 feet long, the heating in each 

 being by steam, within systems of brass tubing 

 that are terminated short of one end ; this being 

 also made sloping, in order further to facili- 

 tate the removal of the scum, and which is con- 

 veniently effected by means of a simple long- 

 handled scraper of light wood, of the width of 

 the pan, and buoyed at the ends with cork, so 

 that it floats on the syrup. In the first pan, he 

 inspissates the juice to (while hot) 15 B. ; and 

 having then drawn it off into a tank to settle 

 for an hour or two, he afterward runs it thence 

 into the smaller pan, adding lime again if neces- 

 sary, boiling gently for a time, until impurities 

 have mainly risen, and then violently to remove 

 the grassy and lime odors, and to secure the 

 best quality of syrup. This being thus reduced 

 to about 36 B., it is finally drawn off through 

 a cooler, into suitable tanks or barrels. Simi- 

 lar pans may be worked over a furnace ; but 

 the ebullition is not in such case so perfectly 

 under control. 



The same writer estimates that two pans, 



4x30 and 2Jx20 feet, well set and heated, 

 requiring a mill of 24 and 14-inch rollers, 22 

 inches in length, and driven by a 6-inch engine, 

 or by 6 horses acting on a leverage of 1 6 feet, 

 the furnace consuming about 4 cords of wood, 

 will, with proper attendance, turn out 300 gal- 

 lons of syrup per day of 15 hours. Mr. Clough 

 considers 1,200 Ibs. of bituminous coal equiva- 

 lent to one cord of good wood, and on theoret- 

 ical grounds concludes that this amount of fuel 

 should, evaporating 10 gallons to 1, give 119 

 gallons of syrup, or, 6 to 1, 215 gallons; but 

 he believes that, in practice, not more than an 

 average of V5 gallons of syrup to the cord of 

 wood are obtained. The megass is yet little 

 used for fuel ; it is in some cases disposed of 

 for the making of paper, but most commonly 

 returned to the land as manure. Mr. Hedges 

 describes a form of furnace for the burning of 

 fresh, wet megass, and which is said to afford 

 an intense heat. The best material for the 

 evaporating pans is undoubtedly heavy sheet 

 copper, which, though expensive, is durable and 

 easily cleaned ; and next to this, Russia iron. 



The scum, where considerable in quantity, 

 should be received into a suitable tank, from 

 the bottom of which some syrup can from time 

 to time be drawn off, to be returned to the 

 pans ; while the tank, to prevent souring, should 

 be emptied and cleansed daily. The scum is 

 used for fattening swine; or, along with other 

 waste, is fermented, affording an excellent vin- 

 egar ; while both may also, and along with the 

 last washings of bone-black filters, if these are 

 employed, be fermented only to the stage at 

 which they yield alcohol. Mr. J. K Leedy, of 

 Bloomington, 111., has devised in quite compact 

 form a sorghum-juice evaporator, furnace, and 

 still the latter for separating alcohol from fer- 

 mented waste-matters of the sorts just named. 



Mr. Clough regards the continuous process 

 as, for concentration of sorghum juice, the most 

 advantageous. The juice being caused to flow 

 in a shallow body continuously and slowly over 

 the bottom of the pan, evaporation is secured 

 with the shortest exposure of the saccharine 

 matter to the destructive action of heat, and 

 which would be aided by the free acids, salts, 

 and other impurities, in which the sorghum 

 juice abounds ; while, under the like circum- 

 stances, the impurities are also very thoroughly 

 expelled. The process is conducted in two 

 forms : in one (represented by the " Jacobs " 

 pan, and by that of Dr. Harris), the flow of the 

 juice is direct from the supply end of the pan 

 to the other, where it is discharged finished or 

 partly finished; in the other (represented by 

 the "Cook" pan), the juice is made to pass 

 back and forth through a series of transverse 

 channels, until it reaches, as syrup, the outlet 

 end of the pan. 



Jacobs' evaporator is a shallow rectangular 

 pan, which, by introducing the transverse 

 wooden partitions not quite fitting to the b'jt- 

 tom, is separated as may be desired into a num- 

 ber of sections, the partitions serving' to keep 



