The Utilization of Bagasse.— The cane after receiving its final crushing, whether passed through two or three mills, contains from 40 to 50 per cent of water and is, therefore, a poor fuel if its value be estimated on the weight of bagasse. If allowed to accumulate it would become a great nuisance about the factory, hence it is consumed as fuel. If the ash con tains silica and alkalies in proportion to form a fusible mixture, a slag will result and choke the furnace by forming a coating over the gratings; for this reason the burning of a mixture of bagasse and molasses has not been satisfactory. Notwithstanding its high water content, it supplies about two-thirds of the fuel in the Louisiana sugar factory and practically all of it in the tropical countries where the percentage of fibre is from 2 to 3 per cent more than in this State. Six tons of wet bagasse or three of water-free, are said to be equivalent to one ton of ordinary bituminous coal. Ex periments at a very great cost have been made to produce paper from bagasse at Sugar Land, Tex., and at Kenilworth Sugar Factory in Louisiana. Neither has been a commercial suc cess, though there has been a considerable amount of rather an inferior grade of brown paper from these mills put on the market in this section. The Kenilworth mill cost about $300,000 and it is said that the running of it for one year added to this amount $50,000 to $60,000 more. This mill is shut down and the bagasse from the last crop was consumed as fuel. The manager of this mill claims that the percentage (about 30 per cent, according to his estimate) of paper-producing fibre is too small, that the color is poor and bleaching is too expensive and that the paper is wanting in strength. The opinion of the writer is that a fair test has not yet been made.
Clarification.— The juice as extracted by the mill has a gray or dark green color, an acid reaction, and contains sucrose, glucose or dextrose, perhaps a little levulose, gums, albu men, organic acid, pectine, the ash or mineral constituents, earthy and coloring matter, fine particles of suspended bagasse, etc. The fol lowing analyses show the composition of three samples of Java cane juice taken respectively from first, second and third mills in triple crushing: These results indicate the composition of cane juice in Java and other tropical countries where cane is grown under most favorable conditions. In Louisiana the juice has from 10 to 15 per cent sucrose, 1 to 2.5 per cent glucose or re ducing sugars and the non-sugars vary from 1 to 3 per cent. There is usually a difference of 2 to 3 per cent sucrose and even more in some instances from the beginning, October, to the end, December and January, of the grind ing season. The reducing and non-sugars also vary very much between the opening and close of the grinding. The purpose of clarification is to remove the impurities as far as possible. This is accomplished by chemicals and heat, causing the soluble impurities to become in soluble or solid. These are removed by settling or filtration. The principal chemicals are sul phur, lime and phosphoric acid. Sulphur is applied as sulphur dioxide which bleaches, dis infects, coagulates some of the albumen and prepares the juice for taking more lime, thereby causing a heavier precipitation which brings about a mechanical cleansing. Sulphur is not much used in the tropical countries where the juice is of a high degree of purity, but it is extensively used in Louisiana and other sec tions where the juice contains large portions of impurities. Lime is universally used and is the most important of all the chemicals em ployed in the sugar factory. It neutralizes acids, acts upon the gums, albuminous substances, coloring matters and, if added in excess, upon the glucose, converting it into organic acids. The lime compounds thus formed are largely insoluble, but some of them are soluble, the in soluble portion is removed by settling or filtra tion and much of the soluble can be got rid of by the addition of phosphoric acid to form the insoluble tri-calcium phosphate, or in some cases sodium carbonate, to form the almost insoluble calcium carbonate. Phosphoric acid is also used to correct any alkalinity resulting from excessive liming and sodium carbonate is very essential in properly correcting the acidity of sour juices. Lime salts, if left in solution in any considerable quantity, give trouble by depositing on the coils of the °effects') and 'xpans,D thereby reducing their efficiency in the evaporation. Carbon dioxide is used to correct
alkalinity and remove excess of lime.
Defecation.— To carry out the process of clarification the juice as it leaves the mill is strained through a copper-wire gauze, then drawn into a sulphur box or tank, if sulphur be used, where it is thoroughly mixed with sulphur dioxide which is produced by the burning of sulphur in an appropriate oven nearby. From the sulphuring apparatus which may consist of a box in which the juice and sulphur gas" are mixed by a pump or of a cylindrical rotating and inclined vessel in which the mixing takes place by rotation, the juice is drawn into meas uring tanks of 2,000 to 6.000 gallons capacity. The clarifiers are rectangular or circular metal lie pans, 700 to 1,200 gallons capacity, provided with a steam coil. These pans may be used also for measuring. In some cases the juice is heated before entering the clarifier, in others it is heated in them. Milk of lime, prepared by slaking and grinding, in especially constructed machines, is added in the clarifiers in sufficient quantity to neutralize, or leave slightly acid, or slightly alkaline, according to the practice of the factory, acid juices being worked to pro duce high-grade sugar and alkaline or neutral to produce low grades. The necessary quantity of lime required for a given quantity of juice is not easily determined. Several methods are in use for this purpose: (1) By the addition of lime until it shows a desired reaction with litmus or turmeric papers. (2) By testing a litre or gallon of the juice with milk of lime and applying the same proportion in the clari fier. (3) An approximate quantity is added, the juice heated, agitated, a small portion fil tered and tested with sucrate of lime (prepared by shaking powdered lime with a 20 per cent sugar solution) which forms a precipitate if an insufficient quantity has been added. More lime is then added and the sucrate test repeated. This testing is repeated until the necessary quantity is obtained (Prinsen Geerligs). (4) The acidity of the juice is determined with a tenth normal caustic soda solution, using phenol phthalein as an indicator. An approximate but insufficient amount of lime according to the soda test is added, the juice heated, agitated, a small portion filtered and again tested with the soda. Now the exact quantity indicated by the soda may be put into the clarifier. On heating the limed juice a portion of the impurities rise to the surface, while others fall to the bottom. In some factories the settling takes place in the clarifiers, while in others the boiled juice is drawn off into large cylindrical tanks provided with conically-shaped bottoms, which facilitate settling. If the former method is used it is the practice of some to brush off the scum of impurities into a trough attached to the side of the clarifier and then allow other suspended particles to subside when the clear liquid is drawn off through a two-way cock and led into the evaporators or °effects.° When all of the clear juice has been drawn off and the mud be gins to show up, the clear-juice cock is closed and the other one is opened and the residual juice with impurities is conducted to a recep tacle provided for this quality of the liquid. The custom in other factories is to beat the limed juice nearly to boiling (about 95° C.), shut off the heat and allow to stand until the heavier particles of the precipitated matter col lect at the bottom. The clear portion of the liquid is then separated as above stated. When settling is to take place in the settling tanks the juice is heated to boiling and at once drawn into these tanks. After complete settling the clear liquid is drawn off in a manner similar to that already described. It is the custom in some factories to filter through heavy canvas bags (one folded within another) the entire volume of juice, that is, the partially clarified Juice, the muddy portion being conveyed to fil ter presses, arranged with cloths that fit in be tween cast-iron plates. The juice is pumped into the filter press where these cloths retain all the solid particles. The juice defecated and clarified as above described is sometimes defe cated a second time, but in a very similar man ner to that already described. This second de fecation may take place immediately after fil tration or in some instances it is after partial concentration or evaporation.