No. VI. Technology. Part III. Defecation, Concluded The quantity of sugar contained in beet root juice varied between certain limits, the determination of which is important. Many various processes, chemical, mechanical, and optical, have been proposed for the attainment of this object, and tables have been computed and published in various works to facilitate the matter. The simplest, however, although a purely empirical method, is the direct use of Baume's areometer (also called Baume's hydrometer, saccharometer, or densimeter), which furnishes, by a very simple calculation, data which we found to approximate sufficiently to the truth,, for all practical purposes. The rule is as follows : 1. Float the Baume areometer, in the saccharine solution, or beet root juice, and read off the degrees of density marked on the scale of the instrument. 2. Multiply the number of degrees thus noted by two, and subtract from the result the same product divided by ten. The result obtained is the percentage of sugar in the liquid, very nearly. If, for instance, the juice indicates a density of ten degrees, Baume, we have: 10 X 2 [(10 X 2) -4- 10]=20 2 18 per cent sugar. If the instrument had marked only 4*8; the per cent of sugar would have been thus found : 4*8 X 2 [(4-8 X 2)-10]=9'6 0-96=:8-64 per cent of sugar. The importance of the determination of the quantity of sugar contained in beets induces us to furnish the exact correspondence existing between each degree of Baume's areometer and the percentage of sugar in a saccharine solution, as given in the books. It is as follows: Per cent Per cent Degrees, Baum . sugar. Degrees, Baume*. su ?ar. 1.................1-72 21................38-29 2.................3.50 23................40-17 3.................5-30 23 ...............42-03 4.................7-09 24................43-93 5.................890 25................4579 6.................10-71 26................47-70 7.................12-52 27................49-60 8.................14-38 28................51-50 9.................16-20 29................53-42 10 ................18-03 30................55-36 11.................19-88 31................57-31 12.................21-71 32................59.27 13.................23-54 33................61-32 14.................25-34 34................6381 15................ .27-25 35................6519 16..................2906 36................6719 17.................3089 37................6919 18................32-75 38................7122 19................36-40 39................73-28 20.................34-60 40................75-35 The lime used for defecation must be of as pure a quality" as possible, and free from potash, a fact which is determined by previous chemical analysis. To prepare it, stir it well into the water added for the purpose of slacking it, so as to convert it into a smooth, creamy mixture, to which water is then added, until the whole bulk of " milk of lime" marks a certain determined density on Baume's areometer. This density must, when once adopted as a standard, be kept constant during the campaign. The strength of the mixture varies between 14 and 20 degrees Baume in different establishments, but must be so regulated that the quantity of lime used shall be intermediate between one-half of one per cent and one per cent of the total weight of the beet roots worked up in the factory. The lime ought to be slaked in considerable masses at one time to insure uniformity of composition, by successive additions of hot water (river or rain water if possible). When it has attained the desired consistency, it must be passed through a metallic screen sieve to remove the solid particles, small pebbles, etc., which may accidentally have been retained. It must be used freshly prepared. A good plan, where the lime is not chemically pure, is to let it rest and settle for a while after having been slaked and watered, to run off the supernatant water, and to repeat the addition of fresh water several times in succession. In this manner any contained potash (which abounds in wood-burned lime) is effectually washed out of it. We have found that heating the milk of lime to the boiling point, before admitting it into the defecating pans, accelerates its action, which it also renders more perfect. It is known by the manufacturer that the right proportion of lime has been added during defecation, when the defecated juice is of a light, clear, transparent, amber color. If, on the contrary, this juice is of a green or greenish hue, and contains many floating opaque particles, the quantity of lime has been insufficient. A few practical trials will soon set matters right i n this respect, under the supervision of an intelligent manager, who who ought to know how to approximate his dose of lime to the quality of the j uice he is working. An excess of lime being detrimental to the economical pro-Viction of sugar, considerable nicety of j udgment and practical experience are required in order to determine the proportion of this substance which ought to be employed; a quantity which varies according to many circumstances, the scientific discussion of which is impossible in the pages of this journal. THE SCUMS OF DEFECATION. The scums formed during the process of defecation of the beet root juice being ricli in saccharine matter must be made to give up as much of their valuable contents as possible. For this purpose they are collected in a special reservoir provided with a wide-mouthed faucet, through which they are filled into sacks. These sacks, made of a strong, close-woven tissue of raw flax, are laid to drip in special tanks, where about two-thirds of the included juice is run out of them in the space of a few minutes. They are then submitted to the action of powerful presses. The liquid obtained from the presses and tanks is taken directly to a monte-jus, from whence it is conveyed to the car-bonatation pans, while the juice from the reservoir is best passed through a small quantity of grained bone-black, covered with a loose permeable cloth, before being run into the same monte-jus. Scums are worked while hot from the defecating pans, and must never be allowed to cool before they are pressed. As the contents of the scum sacks is of a slimy, slippery nature, which would work its way out during the pressing without certain precautions, it is necessary to fold them in a different manner from what we indicated in speaking of the pulp sacks. As soon as a sack has received its contents, a smart shake is given to it so as to collect the scum at the bottom, it is then folded through the middle, as seen in Fig. A, and laid on a table, where it is further folded, as is shown in Fig. B, after which the whole folded portion is tucked underneath, as in Fig. C. It is then ready to be placed between two sheet-iron trays, or in some cases mattings, and taken to the presses. The " dead" scums constitute a very valuable fertilizer, rich in nitrogen and lime, and is hoarded with care until needed for use in tha fields or for sale to the farmer. The specifications for the " scum " department of a factory for working 150,000 lbs. of beet every twenty-four hours are as follows: 1. One reservoir for receiving the scums from the defecating pans, with large faucet, and a capacity of 70 cubic feet. Cost, $60. 2. Two cast-iron tables lor manipulation" of scum sacks. Cost, $50. 3. Two iron presses, with bronze screws. Cost, $400. 4. One montejus and its special reservoir, each of a capacity of SO cubic feet, for scum juice. Cost, $130. The total cost, in gold, of the " scum" department of a 500-acre factory would be $640 in gold. CARBONATATION. The beet root juice, after it has been freed from many obnoxious substances by the process of defecation, is still farfrom constituting pure " sugar and water," and still contains both organic and inorganic matter, beside a portion of the lime which has been used in the former operation. All of these are more or less detrimental to the final crystallization of the sugar and must now be got rid or'. By the old methods, passing the deiecated juice through filters charged with a large quantity of bone-black, fulfilled the desired result, but the loss in sugar and the waste in bone-black were considerable; so much, so indeed, that the new process oi carbonatation (by which an economy of 50 per cent of bone-black was effected) was no sooner discovered, than it was adopted without delay, by every sugar manufacturer in Europe. Carbonatation consists in the saturation of the defecated beet root juice by means of carbonic acid gas. The cheap production of this gas is effected in many different ways, one of which we shall here describe as the simplest and easiest to put in practice. A furnace, of which the figure annexed is a section, fulfills our purpose: The cover, B, on the top of tho furnace, is for the introduction of charcoal, which falls on the grate, A, and spreads itself in the neighboring empty space. Air is admitted through A, which, after favoring tlie combustion of the coal, and having been partly transformed into carbonic acid gas, penetrates into the chamber, C, which is filled with frag-1 ments of limestone. The gas is here partially cooled by coming in contact with the water pans, E E, through which a continuous stream of cold water is allowed to flow. From C the gas next passes into the receiver, D, where it is washed and j purified by being passed through pure water or through water in which a small amount of soda has been dissolved. R is a j pipe through which a double-acting air pump draws the gas out of the receiver, D, and forces it into the liquid to be charged. The same suction causes the necessary draft for sustaining the combustion of the charcoal at A. During the combustion of charcoal, 6 lbs. of pure carbon, combine with 16 lbs. of oxygen to form 22 lbs. of carbonic acid gas, and each 22 lbs. of this gas are sufficient for the I precipitation and elimination of 28 lbs. of the lime retained in the juice. This furnishes all necessary data for the calculation of the quantity needed in any case. The carbonatation pans, into which the combined defecated and scum j uices have been conveyed, are furnished at their bottom with, a pipe pierced with three parallel rows of small holes, one-eighth of an inch in diameter, through which the carbonic acid is forced through the liquid. They are also furnished with coil pipes or double bottoms for heating by steam while the process of carbonatationjs going on. After a certain period of time, whreh is indicated by the cessation of "foaming-," the carbonatated juice is run into large receivers, or decantators, where it is allowed to settle, after which the juice is ready for the filters, unless, as is often done, it is submitted to a double carbonatation. In many works the carbonic gas is obtained by the calcination of limestone instead of the combustion of charcoal. In places where this rock is abundant and of good quality this method has its advantages. The deposit formed during carbonatation is a good manure, which must not be lost or wasted. The specifications and valuations in gold for the carbonatation department of a factory for working, per diem, 150,000 lbs. of beet root, are as follows: 1. Three sheet-iron carbonatation pans, 6 feet in diameter, j and 40 inches high, with copper coil pipe and full comple-1 ment of valves and cocks for admitting steam, for the empty- J ing of the pans, for introducing steam into the gas blowers in j case of obstruction, etc. Cost, $660. 2. Three decantators, each of a capacity of 70 cubic feet, with three bronze cocks to each for drawing off the liquid at various hights. Cost, $240. 3. Three carbonatating pans, same as the first, for second operation. Cost, $660. 4. Three decantators, same as the first, for second opera- j tion. Cost, $240. 5. Six pipes, with stops for distribution of the juice to the carbonatation pans and decantators. Cost, $80. j 6. Casingiind fire box complete, for the gas furnace (exclusive of brickwork). Cost, $250. 7. Wrought-iron gas purifier, 4 feet in diameter, and 8 feet high, with continuous water supply, water level indicator, supply cocks, etc. Cost, $120. 8. Two gas pumps in cast iron, with slides attached to their frames, and with all their connections (two-foot stroke, with 1 foot 8 inches diameter of piston). Cost, 480. 9. Supplementary pipes in copper and iron, not above specified. Cost, $320. Total, for carbonatation department of a 500-acre factory, $3,050 in gold.
This article was originally published with the title "Beet Root Sugar" in Scientific American 20, 18, 276-277 (May 1869)