^LIBRARY 
 
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SUGAR AND SUGAR-MAKING 
 
 BY 
 
 JAMES B. McNAIR 
 
 Assistant Curator of Economic Botany 
 
 Botany 
 Leaflet 13 
 
 FIELD MUSEUM OF NATURAL HISTORY 
 
 CHICAGO 
 1927 
 
 J 
 
LIST OF BOTANICAL LEAFLETS ISSUED TO DATE 
 
 No. 1. Figs $ .10 
 
 No. 2. The Coco Palm 10 
 
 No. 3. Wheat 10 
 
 No. 4. Cacao 10 
 
 No. 5. A Fossil Flower 10 
 
 No. 6. The Cannon Ball Tree 10 
 
 No. 7. Spring Wild Flowers 25 
 
 No. 8. Spring and Early Summer Wild Flowers . . .25 
 
 No. 9. Summer Wild Flowers 25 
 
 No. 10. Autumn Flowers and Fruits 25 
 
 No. 11. Common Trees 25 
 
 No. 12. Poison Ivy 25 
 
 No. 13. Sugar and Sugar- Making 60 
 
 D. C. DAVIES. Director 
 
 FIELD MUSEUM OF NATURAL HISTORY 
 CHICAGO, U.S.A. 
 
Courtesy of the United Fruit Co. 
 
 SIXTEEN SUGAR CANES FROM ONE SEED IN CUBA. 
 
Field Museum of Natural History 
 
 DEPARTMENT OF BOTANY 
 Chicago. 1927 
 
 Leaflet Number 13 
 
 Sugar and Sugar-Making 
 
 Sugar is manufactured by plants for their own 
 use. It is formed in their green parts from carbon 
 dioxide of the air and the water of the sap. Under the 
 influence of sunlight filtered by the green coloring 
 matter (chlorophyll) of the plant, the gas and water 
 combine to form formaldehyde which is later con- 
 verted into glucose and other sugars. 
 
 Sugar is soluble in the plant sap and is carried in 
 the sap to various parts of the plant to be transformed 
 where needed into other substances such as fiber. 
 Some plants store sugar for future use, e. g., for the 
 growth and seed-production of the following year, as 
 is the case with the sugar beet. 
 
 For storage, particles of sugar may unite with 
 each other to form larger, less soluble bodies such as 
 starch due to the union of glucose with glucose in 
 potatoes, the starchlike substance inulin from the sugar 
 levulose with levulose in dahlia tubers, cherry tree gum 
 from the sugar arabinose with arabinose in cherry 
 trees, and gum arabic from the sugar galactose, arabi- 
 nose, and arabinon in acacia trees. 
 
 Sugar may also join with other substances in 
 plants as when glucose unites with gallic acid to form 
 tannin in the oaks and sumacs, rhamnose with fisetin 
 to form the dye stuff fustic in the smoke-wood tree 
 (Rhus Cotinus), and mannose with cellulose to form 
 
 [181] 
 
2 Field Museum of Natural History 
 
 "vegetable ivory" in the kernel of the ivory palm 
 (Phytelephas macrocarpa). Sometimes these com- 
 pounds are poisonous as in the cases of arbutin and 
 amygdalin. Arbutin is found in the trailing arbutus 
 and bearberry, while amygdalin is found in the seeds 
 of the bitter almond, apricot, and peach. 
 
 Besides its use as food for the plant, sugar manu- 
 factured by plants also serves a useful purpose in the 
 nectar of flowers by attracting insects for pollination 
 and in fruits by making these attractive to animals 
 that aid in seed dissemination. Nectar contains for the 
 most part cane sugar, glucose, and levulose, and is 
 taken by bees to form honey. Some flowers contain 
 sufficient nectar to be attractive to man as a source of 
 sugar. Among these are those of the Madhuca tree 
 (Madhuca latifolia), the Honey Flower (Melianthus 
 major), and the Boer Honey Pots (Protea mellifera 
 and Protea cynaroides) . W. Ferguson says that in the 
 time of Manu, about 4,000 years ago, the Hindus knew 
 how to make sugar from the flowers of the Madhuca 
 tree. The natives of Cape Colony collect the Honey 
 Flowers for the large quantity of sugar they contain, 
 and the Boers of South Africa make use of the Honey 
 Pot flowers for the same purpose. 
 
 Many different sugars occur in nature in plants 
 and animals. Other sugars not yet found in nature 
 are produced synthetically in the laboratory. The gen- 
 eral term "sugar" applies to a large number of sub- 
 stances composed of three elements, carbon, hydrogen, 
 and oxygen combined in certain proportions. Sugars 
 which possess distinct chemical and physical prop- 
 erties are distinguished by special names, e. g., sucrose. 
 The sugars belong to a much larger group of sub- 
 stances called carbohydrates, most of which conform to 
 the general formula C m (H 2 0)„, where m and n stand 
 for various multiples. See outline on page 4. The 
 
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Sugar and Sugar-Making 5 
 
 other plant substances of this group, cellulose, starch, 
 and gum, are more complex but may be decomposed 
 or broken down into various sugars. 
 
 Commercial sugars are named after the particular 
 plants from which they are extracted, for instance, 
 cane, beet, maple, sorghum, palm. The chief con- 
 stituent of all these is a single substance — sucrose or 
 saccharose. Corn and grape sugar on the contrary 
 consist of another chemical substance — glucose. 
 
 All sugars are not of equal sweetness. Corn sugar 
 (glucose) is only three-fifths as sweet as cane sugar, 
 while levulose is about equal to cane sugar in sweet- 
 ness. 
 
 CANE SUGAR 
 
 The sugar cane (Saccharum, officinale) belongs to 
 the grass family (Gramineae) which includes wheat, 
 oats, corn 1 (maize) , sorghum, etc. ; but the sugar cane 
 towers above most of them, sometimes attaining a 
 height of twenty feet. Its native country is Southern 
 or Southeastern Asia. Being a plant of the moist 
 tropics and subtropics, it grows successfully only 
 where the average temperature does not fall much be- 
 low 80° Fahrenheit nor the rain below sixty inches a 
 year. 
 
 History. — Various classical writers of the first cen- 
 tury noticed the sweet sap of the Indian honey-bearing 
 reed or its granulated saltlike product. This product 
 was imported to Europe from India and from Arabia 
 and Opone (these being entrepots of Indian trade) un- 
 der the name of saccharum (<janxa.pi from Sanskrit 
 sarkara, gravel, sugar), for medical use. 
 
 Before the Middle Ages Europeans had no clear 
 idea of the origin of cane sugar. It was confounded 
 
 'The Aztecs in Mexico made use of the corn plant for sugar 
 in the same manner as sugar cane is used now. 
 
 [185] 
 
6 Field Museum of Natural History 
 
 with manna or was thought to exude from the stem of 
 a plant, on which it dried into a kind of gum. The art 
 of boiling sugar was known in Gangetic India, from 
 which it was carried to China in the first half of the 
 seventh century ; but sugar refining cannot have been 
 known then, for the Chinese learned the use of ashes 
 for this purpose only in the Mongol period (600 A. D.) , 
 from Egyptian visitors. The cultivation of the cane 
 in the West spread from Khuzistan in Persia. At 
 Gunde-Shapur in this region "sugar was prepared 
 with art" about the time of the Arab conquest, and 
 its manufacture on a large scale was carried on at 
 Shuster, Sus, and Askar-Mokram throughout the 
 Middle Ages. It has been plausibly conjectured that 
 the art of sugar refining, which the farther East 
 learned from the Arabs, was developed by the famous 
 physicians of this region, in whose pharmacopoeia 
 sugar had an important place. Under the Arabs, the 
 growth and manufacture of the cane spread far and 
 wide, from India to Sus in Morocco, and was also in- 
 troduced in Sicily and Andalusia. 
 
 In the age of discovery, the Portuguese and Span- 
 iards became the great disseminators of the cultiva- 
 tion of sugar; the cane was planted in Madeira in 
 1420; it was carried to San Domingo in 1494; and it 
 spread over and occupied portions of the West Indies 
 and South America early in the sixteenth century. 
 Within the first twenty years of the sixteenth century 
 the sugar trade of San Domingo expanded with great 
 rapidity, and it was from the dues levied on the im- 
 ports brought thence to Spain that Charles V obtained 
 funds for his palace-building at Madrid and Toledo. 
 
 In the Middle Ages, Venice was the great Europe- 
 an center of the sugar trade, and toward the end of the 
 fifteenth century a Venetian citizen received a reward 
 of 100,000 crowns for the invention of the art of mak- 
 
 [186] 
 
8 Field Museum of Natural History 
 
 ing loaf sugar. One of the earliest references to sugar 
 in Great Britain is that of 100,000 pounds of sugar 
 being shipped to London in 1319 by Tomasso Lore- 
 dano, merchant of Venice, to be exchanged for wool. 
 In the same year there appears in the accounts of the 
 Chamberlain of Scotland a payment at the rate of 
 Is 9*4^ per pound for sugar. Throughout Europe it 
 continued to be a costly luxury and article of medicine 
 only, till the increasing use of tea and coffee in the 
 eighteenth century brought it into the list of prin- 
 cipal food staples. The increase in the consumption is 
 exemplified by the fact that, while in 1700 the amount 
 used in Great Britain was 10,000 tons, in 1800 it had 
 risen to 150,000 tons, and in 1885 the total quantity 
 used was almost 1,100,000 tons. In 1924-25 the 
 United States produced 88,483 of a world-production 
 of 17,649,000 short tons. 
 
 Sugar cane was introduced into Louisiana from 
 San Domingo by the Jesuits in 1751. Dubeuil built the 
 first cane-mill, and his efforts at manufacture failed. 
 The first refined sugar was made by Antonio Mendez 
 in 1792, but the first refined sugar on a commercial 
 scale was made in 1794 by Etienne de Bore. The 
 plantations of these two planters now form part of 
 the city of New Orleans. 
 
 The manufacture of sugar was very crude up to 
 1700. Inefficient mills operated by wind, water, or 
 oxen were used for extraction with lime, clay, and 
 ashes as purifying agents; the evaporation was ef- 
 fected in open copper or iron pans placed directly over 
 the fire, and the refining consisted in melting, boiling, 
 and recrystallizing. These crude methods still exist 
 in some countries, especially in districts where cane 
 is grown for making syrup and very crude sugar. 
 
 Extraction. — There are in practice two methods 
 of extracting the sugar from cane, namely, milling 
 
 [188] 
 
Sugar and Sugar-Making 9 
 
 and diffusion. The older and more generally used is 
 milling, the diffusion being confined almost entirely to 
 manufacture of sugar from beets. A mill may consist 
 of two or three rollers, usually placed horizontally and 
 varying in length from eighteen to seventy-two inches, 
 and in diameter from twelve to thirty-two inches. If 
 the mill is to be operated by oxen or by horses the 
 rollers are set in an upright position. The most primi- 
 tive mill was the wooden roller. This has been used 
 in a small way in some of the southern states since 
 the Civil War, but there is at this time, perhaps, not 
 one in existence in this country. In most large 
 factories there are two of these three-roller mills and 
 in some three. The rollers are so arranged that two 
 are placed on a level and geared to move in the same 
 direction while the third moves in the opposite direc- 
 tion. If a factory operates two mills, the rollers of the 
 first are farther apart than those of the second, and if 
 three mills, the third has its rollers closer together 
 than the second. These rollers revolve very slowly 
 (one and a half to two and a half revolutions per min- 
 ute) and are operated under great pressure. To re- 
 lieve the strain upon the mill, a cane crusher or 
 shredder has come into general use. The cane enters 
 one of these as it leaves the cane carrier and is either 
 crushed or shredded into small pieces before reach- 
 ing the mill. This not only relieves the mill of the work 
 of crushing the whole cane, but increases its capacity. 
 The capacity of mills will vary from 200 to 1,400 tons 
 of cane per day and the extraction is 70-80 per cent 
 of the weight of cane and 90-95 per cent of the sugar 
 in the cane. Between the first and second mill the 
 juice receives a spray, through a perforated pipe, of 
 either hot or cold water, the object being to dilute the 
 sugar so that a large percentage will be crushed out 
 by the second mill. This addition of water is termed 
 
 [189] 
 
10 Field Museum of Natural History 
 
 maceration, and the quantity of water added may vary 
 from 5 to 15 per cent of the weight of the cane and in 
 some cases as much as 20 per cent, the quantity de- 
 pending somewhat upon the value of fuel and the 
 capacity of the evaporating outfit. In some instances 
 the diluted juice from the third mill is returned and 
 used for macerating the crushed cane between the 
 first and second mill, and water is used between the 
 second and third. 
 
 Diffusion has been practiced at several factories in 
 Louisiana and some other countries, but it has not yet 
 met with very great favor. 
 
 Purification of the juice. — The juice as extracted 
 by the mill has a gray or dark-green color, an acid 
 reaction, and contains sucrose, glucose, perhaps a little 
 levulose, gum, protein, organic acids, pectin, ash or 
 mineral constituents, soil, coloring matter, fine par- 
 ticles of suspended cane, etc. 
 
 Primitive methods for purifying the juice do not 
 differ essentially from the practice of today. The 
 juice extracted in crude mills was heated in an iron 
 vessel over a wood fire. Ashes from the fire were 
 added to the hot juice. A dark scum was thus caused 
 to form and was removed. The juice was concentrated 
 by boiling to a thick syrup and slowly cooled. This 
 practice is still employed in China and India. The 
 chemical action of wood ashes is now easily explained 
 by its alkaline constituent, carbonate of potash, which 
 precipitates certain non-sugars in the juice and forms 
 a dark scum. 
 
 For large-scale manufacture more economical 
 methods of heating the juice were evolved. Steam 
 heat was first employed in 1785. Other alkalies soon 
 came into use, for instance, carbonate of soda, which is 
 used in India to the present day. The cheaper alkali, 
 
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Sugar and Sugar-Making 
 
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 slaked lime, was first employed in addition to wood 
 ashes in 1750 and finally substituted for it. 
 
 In the modern factory, the object of the chemical 
 treatment is threefold: 
 
 1. Clarification by the precipitation of dissolved 
 non-sugars. 
 
 2. Defecation or the separation of insoluble solid 
 matter which has not been removed by the filter but 
 remains suspended in the juice. 
 
 3. Refining. This treatment is only adopted in 
 the manufacture of white and yellow sugars intended 
 for direct consumption. 
 
 The purpose of clarification is to remove the im- 
 purities as far as possible. This is accomplished by 
 chemicals and heat, causing the soluble impurities to 
 become insoluble so that they may be removed by 
 settling or filtration. The principal chemicals are 
 sulphur, lime, and phosphoric acid. Sulphur is ap- 
 plied as sulphur dioxide which bleaches, disinfects, 
 and coagulates some of the protein and prepares the 
 juice for taking more lime, thereby causing a heavier 
 precipitation which brings about a mechanical cleans- 
 ing. Sulphur is not much used in the tropical coun- 
 tries where the juice is of a high degree of purity, but 
 it is extensively used in Louisiana and other sections 
 where the juice contains large portions of impurities. 
 Lime is universally used and is the most important of 
 all the chemicals employed in a sugar factory. It 
 neutralizes acids, acts upon the gums, protein sub- 
 stances, coloring matters, and, if added in excess, upon 
 the glucose, converting it into organic acids. The lime 
 compounds thus formed are largely insoluble, the in- 
 soluble portion is removed by settling or filtration and 
 much of the soluble can be gotten rid of by the addi- 
 tion of phosphoric acid or sodium carbonate, to form 
 the insoluble lime salts. Phosphoric acid is also used 
 
 [192] 
 
Sugar and Sugar-Making 13 
 
 to correct any alkalinity resulting from excessive lim- 
 ing, and sodium carbonate is very essential in prop- 
 erly 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 
 "pans," thereby reducing their efficiency in the evapo- 
 ration. Carbon dioxide is used to correct alkalinity 
 and remove excess of lime. 
 
 To carry out the process of clarification, the juice 
 is strained through a copper-wire gauze as it leaves 
 the mill, then drawn into a sulphur box or tank, if 
 sulphur is used, where it is thoroughly mixed with 
 sulphur dioxide which is produced by the burning of 
 sulphur in an appropriate oven near by. 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 measuring tanks. The clarifiers are 
 large rectangular or circular metallic pans, provided 
 with a steam coil. In some cases the juice is heated be- 
 fore entering the clarifiers, in others it is heated in 
 them. Milk of lime, prepared by slaking and grinding, 
 is added to the juice in the clarifiers in sufficient quan- 
 tity to neutralize it, or leave it slightly acid or alkaline. 
 This is done in accordance with the practice of the 
 factory, acid juices being worked to produce high- 
 grade sugar and alkaline or neutral to produce low 
 grades. On heating the limed juice a portion of the 
 impurities rise to the surface, while others fall to the 
 bottom. It is the custom in some factories to filter 
 through heavy canvas bags (one folded within an- 
 other) the entire volume of juice, that is, the partial- 
 ly clarified juice, the muddy portion being conveyed 
 to filter presses, arranged with cloths that fit in be- 
 tween cast-iron plates. The juice is pumped into the 
 
 [193] 
 
Sugar and Sugar-Making 15 
 
 filter press where these cloths retain all the solid 
 particles. In recent years there has been added to 
 the ordinary process a super-heating apparatus by 
 which some of the soluble material is converted into 
 insoluble material at a temperature 15-30° Fahrenheit 
 above boiling. 
 
 Evaporization and crystallization. — The evapora- 
 tion of sugar solutions or cane juice has for its object 
 a concentration of the liquid to such density as will 
 cause the sugar to crystallize out. To accomplish this 
 there are two methods, the "open kettle" and the 
 vacuum pan. The open-kettle process consists in boil- 
 ing the juice in open pans, either of circular or rec- 
 tangular form, provided with steam coils. The heat 
 is continued until the density indicates sufficient cook- 
 ing. When a density of 22° or 36° Baume is reached, 
 the liquid is termed a syrup, and when the syrup is 
 cooked to a stiff mass, massecuite. After allowing 
 crystallization to take place in wood or iron vats, the 
 massecuite is thrown into a hogshead and the molasses 
 percolates through a perforated bottom, or the sugar 
 and molasses may be separated in a centrifugal ma- 
 chine. The sugar thus made is termed open kettle, 
 and the process is not used in the up-to-date factory. 
 
 The vacuum apparatus for evaporating sugar 
 solutions consists of a dome-shaped vessel, provided 
 with coils of steam pipes and requires only about one- 
 third the fuel of the open-kettle process and reduces 
 to a minimum the loss by burning or inversion to 
 glucose and fructose. 
 
 The syrup is drawn from the syrup tank into the 
 vacuum pan until one, two, or three coils are covered, 
 and this definite quantity is heated until grains of 
 sugar may be seen on withdrawing a sample and 
 spreading it on a piece of glass. The formation of 
 crystals is sometimes brought about by permitting a 
 
 [195] 
 
16 Field Museum of Natural History 
 
 little cold juice to enter the pan and suddenly cool it. 
 The object here is to form a crop of "seed crystals," 
 and the remainder of the process has for its purpose 
 the increase in size of the crystals to a desired point. 
 This is accomplished by continuing the boiling and 
 adding, from time to time, small quantities of the 
 syrup, taking care that no more grains or crystals are 
 formed. In three to four hours the pan will be as full 
 as is convenient to cook it and the sugar crystals as 
 large as desired. If very large crystals are wanted, 
 as is sometimes the case with confectioners' sugar, a 
 "cut" strike is made. That is, one-third or one-half 
 the sugar in the pan is removed and the remaining 
 portion is built up in the same manner as already de- 
 scribed. On completing the boiling the second time 
 there are not so many crystals, but they are twice as 
 large. This process may be repeated, but it is very ex- 
 pensive. The cooking is continued until the concen- 
 trated mass contains 6-8 per cent of water. The 
 discharging of the pan is termed a "strike," and the 
 product discharged, massecuite. This is conveyed to 
 a mixer provided with a shaft carrying paddles or lin- 
 gers that keep the sugar and adhering molasses mixed. 
 The well-mixed massecuite is next conveyed to a cen- 
 trifugal machine, made to revolve 1,000 to 1,200 times 
 per minute, and in its rapid motion the sugar and 
 molasses are separated, the latter being ejected 
 through very small perforations, while the sugar re- 
 mains in the basket. The product thus obtained is 
 termed "first sugar," or "raw sugar," and is usually 
 of 96 per cent purity. 
 
 The utilization of bagasse. — The cane, after re- 
 ceiving its final crushing (bagasse), 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. Even though 
 
 [196] 
 
- T r 
 
 Courtesy of the United Fruit Co. 
 
 CENTRIFUGAL MACHINES FOR CANE SUGAR IN CUBA. 
 
18 Field Museum of Natural History 
 
 it is poor fuel it is used as such for if allowed to ac- 
 cumulate it would become a great nuisance about the 
 factory. If the ash contains silica and alkalies in pro- 
 portion 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. Not- 
 withstanding 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 bulk of fiber is from 2 to 3 per cent greater. 
 
 Bagasse can also be made into paper. The first 
 patent for paper manufacture from bagasse was issued 
 in 1838. The first large-scale experiment was carried 
 on in Texas in a sugar factory. This was a commercial 
 failure and was abandoned. The experiments on the 
 Tacarigua Estate, Trinidad, were more successful. 
 There bagasse was mixed with bamboo and Para grass 
 and made into paper. The manufacture of this paper 
 was carried on in 1915 by a sugar factory in Cuba. Im- 
 provements in the process have resulted in the making 
 of "wall board" and paper suitable for newspaper 
 and better grades of wrapping paper. 
 
 BEET SUGAR 
 
 Sugar was noticed in the ordinary beet in 1590 by 
 Oliver des Serres, but received no further attention as 
 a source of sugar until Margraff, a member of the 
 Berlin Academy of Science, in 1747, conducted an in- 
 vestigation of the sugar content of various plants. 
 The sugar content of the common garden beet is very 
 small, being from 2 to 4 per cent. The sugar beet is 
 a variety of this derived by selection and cultivation 
 from the wild beet of the coast of Europe. 
 
 Great interest in both Germany and France fol- 
 lowed the investigation of Achard in 1799 and by 
 
 [ 198 ] 
 
Sugar and Sugar-Making 19 
 
 1812 there were many factories established. Napoleon 
 added greatly to the progress of this industry by gov- 
 ernment aid and by the establishment of sugar schools. 
 After the new industry had become well established, 
 it was almost obliterated by destructive wars. It was, 
 however, soon revived in France and by 1829 a yield 
 of 4,000 tons of sugar was made, but Germany's in- 
 terest was not resumed until 1835. From these coun- 
 tries the industry has spread throughout Europe until 
 the production for 1924-25 has been estimated at 
 8,957,289 short tons for the world of which the United 
 States produced 1,172,000. 
 
 The first experiments with sugar beets in the 
 United States were made by two Philadelphians in 
 1830. About ten years later David Lee Child, North- 
 ampton, Massachusetts, attempted beet culture and 
 the manufacture of beet sugar. He produced 1,300 
 pounds at a cost of eleven cents per pound. These en- 
 terprises failed and seem to have discouraged fur- 
 ther efforts until Gennert Brothers, natives of Bruns- 
 wick, Germany, inaugurated a plant at Chatsworth, 
 Illinois, in 1863, which failed, and it may be said that 
 this industry was not permanently established until 
 between 1875 and 1880. From this time sugar beet 
 culture has been successfully conducted in the United 
 States. 
 
 Extraction. — The beets are first washed in tanks. 
 From the washing tanks, the beets are carried to a 
 slicing machine, where they are cut into very thin, 
 narrow pieces so that when the chips fall they will not 
 lie too compactly one upon the other. The chips are 
 conveyed from the slicing machine to a hopper feeding 
 a battery of twelve to fourteen cast-iron cylindrical 
 cells connected with each other by a system of pipes 
 with cocks between, so that one may empty and fill 
 without interfering with the operation of the rest. 
 
 [199] 
 
Sugar and Sugar-Making 21 
 
 The extraction of the sugar consists in washing the 
 chipped beets with hot water. When the sugar has 
 been extracted from the beets, the bottom of the cell 
 is opened and the beets discharged and led to a press 
 where most of the remaining water and sugar are 
 pressed out. The pulp cake is used in the wet condition 
 for cattle food or it may be dried by means of the ex- 
 haust steam so it can be preserved for the same pur- 
 pose. It may also be used as a fertilizer. 
 
 The purification of the extracted sugar solution 
 consists of the application of lime, carbon dioxide, and 
 sulphur, together with settling and filtering. The use 
 of the lime followed by carbon dioxide is termed 
 carbonation. These two materials, lime and carbon 
 dioxide, are obtained by burning limestone in a kiln 
 constructed for that purpose at the factory. The 
 limestone is decomposed and the lime, mixed with 
 water, is added to the sugar solution in a quantity 
 equal to 2 or 3 per cent. The gas is led from the lime 
 kiln through water to wash it and admitted into a 
 large cell provided with coils of steam pipes so the 
 solution may be heated. The temperature at which 
 the carbonation is carried on is 176-94° Fahrenheit. 
 This process of adding lime, then charging with car- 
 bon dioxide, is repeated two or three times, depending 
 upon the quality of the juice, but after the first treat- 
 ment the juice is filtered each time before repeating 
 the carbonation. Finally the juice is treated with 
 sulphur dioxide, which is used to bleach the solution, 
 and then the excess of this gas or acid is removed by 
 the addition of lime and the juice is again treated with 
 carbon dioxide. Before filtering, the juice is allowed 
 to settle so that the impurities may collect at the 
 bottom of the settling tank. The clear liquid is drawn 
 off and filtered through bags. The clarified juice is 
 treated the same as that of cane sugar. 
 
 [201] 
 
22 Field Museum of Natural History 
 
 The molasses containing 40-50 per cent of sugar, 
 discharged by the centrifugal, must be treated for the 
 sugar which it contains, though some of the cane 
 sugar molasses is sold to merchants for direct con- 
 sumption as table molasses, or to confectioners and to 
 glucose mixers for the preparation of glucose syrup. 
 Generally, this molasses is recooked over and over 
 again until all of the crystallizable sugar has been 
 separated. The first reboiling yields "second sugar" 
 and "second molasses," the second reboiling "third 
 sugar" and "third molasses," etc. The massecuite is 
 returned to the centrifugal, and the crystals separated 
 from the molasses. The second sugar may be sold 
 to the refineries, but as it falls below the 96 per cent 
 sugar (probably the most profitable grade), it is melt- 
 ed in hot sugar juice and turned out as first sugar. 
 The second molasses is reboiled to "string proof," put 
 into large tanks and allowed to remain at rest from 
 four to six months, when the crystallized mass is sub- 
 jected to centrifuging. The third molasses usually 
 contains a large portion of impurities which may make 
 it unprofitable to reboil it further, though some work 
 this molasses for fourth sugar. All of the foregoing 
 grades of sugar recovered by reboiling may be worked 
 back into a first sugar or sold to the refineries. 
 
 The refuse or exhausted molasses, which amounts 
 to from four to five gallons per ton of cane and carries 
 25-40 per cent sugar, has increased very much in 
 value in recent years, selling at six to ten cents per 
 gallon. Some of it is fed to stock and some consumed 
 by distillers. 
 
 REFINING OF CANE AND BEET SUGAR 
 
 White-sugar loaves were first manufactured from 
 cane sugar many centuries before the introduction of 
 the present refining process which was probably de- 
 
 [202] 
 
Sugar and Sugar-Making 23 
 
 rived from the Arabs. Boiled sap was allowed to 
 crystallize in conical molds, and the mother-liquor 
 drained through a hole in the point. Such sugar 
 loaves were first imported to Great Britain in 1319, 
 and appeared at the coronation banquet of Henry V in 
 1413. 
 
 In 1812 Howard, the inventor of the vacuum pan, 
 patented the use of saturated sugar solutions for 
 washing the sugar loaves in place of the old process of 
 claying. Purification by recrystallization was adopt- 
 ed as early as the thirteenth century. Some of these 
 recrystallized loaves were exported from Cypress, 
 Rhodes, Syria, and Alexandria between 1250 and 
 1400. The present system of refining is based on this 
 principle, but with the addition of a decolorizing proc- 
 ess applied to the solution of raw sugar before re- 
 crystallization. The bleaching agent — bone char — first 
 used for decolorizing vinegar in 1810 was later ap- 
 plied to sugar. The next improvement was carbona- 
 tion which the cane sugar refiners borrowed from the 
 beet sugar manufacturers. 
 
 COMPARISON OF CANE AND BEET SUGAR 
 
 No one can distinguish between highly refined 
 cane and beet sugar, as they are one and the same 
 thing. Between the crude or raw beet and cane sugar 
 there is a great difference, the latter being edible 
 whereas the former is not, as it possesses a very 
 disagreeable odor and taste. Cane sugar molasses 
 is good for culinary purposes, beet sugar molasses is 
 unsuitable. 
 
 MAPLE SUGAR' 
 
 Maple sugar production is an industry almost en- 
 tirely confined to Northeastern North America. The 
 
 'Other deciduous trees have been tapped for sugar. The 
 butternuts and birches were made use of in this way by some 
 of the early American colonists. 
 
 [203] 
 
24 Field Museum of Natural History 
 
 manufacture of this sugar was known to the Indians, 
 for Jeffreys, 1760, says that in Canada "this tree af- 
 fords great quantities of a cooling and wholesome 
 liquor from which they make a sort of sugar," and 
 Jonathan Carver, in 1784, says the Nandowessie In- 
 dians of the West "consume the sugar which they have 
 extracted from the maple tree." In 1870, the Winne- 
 bagoes and Chippewas are said to often sell to the 
 Northwest Fur Company 15,000 pounds of sugar a 
 year. The sugar season among the Indians is a sort 
 of carnival, and boiling candy and pouring it out on 
 the snow to cool is the pastime of the children. 
 
 The following paragraph is from a book written 
 by the eminent Robert Boyle (the discoverer of Boyle's 
 Law) and printed at Oxford in 1663: 
 
 There is in some parts of New England a kind of tree . . . 
 . . . whose juice that weeps out of its incisions, if it be permitted 
 slowly to exhale away the superfluous moisture, doth congeal 
 into a sweet and saccharin substance, and the like was con- 
 firmed to me by the agent of the great and populous colony of 
 Massachusetts. 
 
 Maple sap contains 2-6 per cent of sugar and aver- 
 ages about 3 per cent. Eighty to 90 per cent of all 
 maple sugar is made from the sap of four species: 
 the sugar maple (Acer saccharum), the black maple 
 (Acer nigrum), the red maple (Acer rubrum), and 
 the silver maple (Acer saccharinum) . 
 
 From nine to fifty-seven days of the year are used 
 in gathering maple sap with an average of thirty- 
 four days per year. The season lasts from the middle 
 of March to the middle of April from Vermont to 
 New York. In Ohio and western New York it extends 
 from late February to early April. 
 
 The yield of sap varies considerably with the sea- 
 son, size of tree, character of tapping, and many other 
 conditions. A tree averages a yield of three pounds 
 
 T204] 
 
26 Field Museum of Natural History 
 
 of sugar per season and may vary from one to seven 
 pounds per tree. From five to forty gallons of sap 
 may be had yearly from each tree. Thirty-two gal- 
 lons of sap are made into one gallon of syrup and four 
 and a quarter gallons of sap contain one pound of 
 sugar. 
 
 To make the sugar, the syrup is heated until it is 
 so thick that it pours slowly or becomes waxy in the 
 snow or in cold water or reaches a temperature of 
 230° Fahrenheit. It is then poured into molds. The 
 first run of sap always makes the best sugar and the 
 last of the season sometimes fails to "cake." During 
 the heating, scum is taken off the surface by skim- 
 ming; the sap gradually turns to an amber color as 
 it reaches the syrupy stage and deposits malate of lime 
 (called "niter" in Vermont and "silica" in Ohio) . 
 
 In 1860 the total production of maple sugar and 
 syrup in the United States reached its height. It fell 
 heavily in 1870, arose again to large proportions in 
 1880, remained stationary in 1890, and then suddenly 
 fell almost 50 per cent in 1900, when the total amount 
 produced was nearly one-third less than in 1850. The 
 quantity produced in 1923 was about one-half that of 
 1900 and amounted to 4,685,000 pounds of sugar and 
 3,605,000 gallons of syrup. This reduction has been 
 caused in part by the felling of the trees for lumber, 
 etc., insect attacks, adulteration, and the decrease in 
 the price of cane sugar. 
 
 COMPARISON OF CANE AND MAPLE SUGAR 
 By 1875 cane sugar became cheap enough to 
 undersell that of maple. Since 1885 maple sugar has 
 been a luxury only. In this capacity its prospects are 
 much better than formerly although the adulteration 
 of maple syrup with glucose and cane sugar has tended 
 to keep down the price of maple sugar. 
 
 [206] 
 
Sugar and Sugar-Making 27 
 
 SORGHUM SUGAR 
 
 The stem of the Guinea corn, or sorghum (Sorg- 
 hum saccharatum) , has long been known in China as 
 a source of sugar. The sorghum is hardier than the 
 sugar cane; it comes to maturity in a season; and it 
 retains its maximum sugar content a considerable 
 time, giving opportunity for leisurely harvesting. 
 The sugar is obtained by the same method as cane 
 sugar. 
 
 Many experiments have been made to produce 
 sugar from sorghum on a commercial scale but the re- 
 sults have not been profitable. There is now very little, 
 if any, sugar made from sorghum, although there is 
 considerable syrup. 
 
 PALM SUGAR 
 
 Palm sugar which comes into the European markets 
 as jaggery or khaur is obtained from the sap of sev- 
 eral palms, the wild date (Phoenix sylvestris) , the 
 palmyra (Borassus flabellifer) , the cocoanut (Cocos 
 nucifera) , the gomuti (Arenga saccharif era) , and 
 others. 
 
 The palm sugar industry of India is a very old 
 one, but insignificant compared with the sugar-cane 
 industry of that country. A fair estimate places the 
 annual production of Indian palm sugar at about 
 100,000 tons. 
 
 The sap of the palmyra and cocoanut palms is ob- 
 tained from their young flowering branches. These 
 palms do not bloom until they are from twelve to fif- 
 teen years old. The sugar-gathering season which lasts 
 for several months commences with the appearance of 
 these branches or spadices in November or December. 
 The spathes are bruised and cut, and their juice or 
 toddy caught in a suspended chatty or toddy receiver. 
 A spadix continues to give toddy for about five months, 
 
 [207] 
 
Sugar and Sugar-Making 29 
 
 at the rate of three or four quarts a day. Seldom more 
 than three spadices yield toddy on the cocoanut tree 
 at the same time, but seven or eight will yield juice at 
 once on the palmyra palm. An expert climber can 
 draw toddy from about forty trees in a few hours. It 
 is said that if the operation be repeated on the same 
 tree for three successive years, without allowing any 
 of the buds to bloom, the tree will die. 
 
 To obtain sugar from the sap, the "toddy" is 
 boiled until it becomes a thick syrup. It may then be 
 poured into small baskets of palmyra leaf to cool and 
 harden into "jaggery," or it is formed into round cakes 
 and wrapped in pieces of dried banana leaves. About 
 three quarts of toddy are sufficient to make one pound 
 of crude sugar or jaggery. 
 
 Other palms of which the juice of the spadices 
 is a source of sugar are: the fish-tail palm (Caryota 
 urens), the gomuti palm (Arenga saccharifera) , and 
 the African oil palm (Elaeis guineensis). 
 
 The wild date palm (Phoenix sylvestris) is tapped 
 for its sap as a source of sugar quite similarly 
 to the maple tree. In many localities, especially in 
 Jessore and other districts of Bengal, the wild date 
 palm is of importance in this regard. In 1889, some 
 168,262 acres were under cultivation here. The fol- 
 lowing account of the process of tapping the trees 
 and of the manufacture of sugar from the sap comes 
 from Sir James Westland. 
 
 When the tree becomes six or seven years old 
 tapping begins and is continued each year there- 
 after. When the rainy season has completely passed, 
 the cultivator cuts off the lateral leaves of one-half 
 of the circumference, and in this manner leaves bare 
 a surface measuring about 10 or 12 inches square. 
 
 After the tree has remained in this condition for 
 a few days, the tapping is performed by making a cut 
 
 [209] 
 
30 Field Museum of Natural History 
 
 into this exposed surface, in the shape of a very broad 
 V, about three inches wide and a quarter or half inch 
 deep. Then the portion inside the angle of the V is 
 cut deeper, so that a triangular surface is cut into the 
 tree. From this the sap exudes. Caught by the sides 
 of the V, it runs down to the angle, where a bamboo 
 of the size of a lead pencil is inserted in the tree to 
 catch the dropping sap and carry it out as by a spout. 
 The tapping is arranged throughout the season 
 in periods of six days each. On the first evening a 
 cut is made as just described, and the juice is al- 
 lowed to run during the night. This juice is the 
 strongest and best, and is called jiran juice. In the 
 morning the juice collected in a pot hanging beneath 
 the bamboo spout is removed. The flow of juice stops 
 during the day. So in the evening a new cut is made, 
 not nearly as deep as the last, but rather a mere par- 
 ing, and for a second night the juice is allowed to run. 
 This juice is termed do-kat and is not quite so abund- 
 ant or so good as the jiran. The third night no new 
 cutting is made, but the exuding surface is merely 
 made quite clean, and the juice which then runs is 
 called jarra. It is still less abundant and less rich 
 than the do-kat, and toward the end of the season, 
 when the weather is getting hot, it is unfit even for 
 sugar manufacture, the gur (molasses) made from it 
 being sold simply as "droppings." These three nights 
 are the periods of activity in the tree, and after these 
 three it is allowed to remain for three nights at rest, 
 when the same process is repeated. Of course, 
 every tree in the same grove does not run in the same 
 cycle, some are at their first, some at their second 
 night, and so on; and thus the owner is always busy. 
 Since every sixth day a new cut is made over the 
 previous one, the tree gets more and more hewed into 
 as the season progresses, and toward the end of the 
 
 [210] 
 
Sugar and Sugar-Making 31 
 
 season the exuding surface may be, and often is, as 
 much as four inches deep. The cuts during the whole 
 of one season are made about the same place, but in 
 alternate seasons alternate sides of the tree are used 
 for the tapping; and as each season's cutting is thus 
 above the previous season's and on the opposite side, 
 the stem of the tree has a curious zigzag appearance. 
 The age of a tree can of course be at once counted up 
 by enumerating the notches and adding six or seven, 
 the number of years passed before the first year's 
 notch. More than forty notches have been counted on 
 a tree, but one rarely sees them so old. When they are 
 forty-six years old they are worth little as sugar-pro- 
 ducing trees. It is somewhat remarkable that the 
 notches are almost always on the east and west sides 
 of the tree and very rarely on the north and south 
 sides; also that the first notch appears to be made on 
 the east side in by far the majority of instances. 
 
 One may expect from a good tree a regular aver- 
 age of five pints of sap per night (excluding the 
 quiescent nights) . The colder and clearer the weather, 
 the more copious and rich the juice. In the beginning 
 of November tapping begins. In December and Jan- 
 uary the juice flows best, beginning sometimes as early 
 as 3 P.M., and decreasing with the coming of the warm 
 days of March. If the cultivator begins too early, or 
 continues too late, he will lose in quality and quantity 
 as much as he will gain by extending the tapping 
 season. 
 
 The next process is the boiling, and this every 
 rayat does for himself, and usually within the limits 
 of the grove. Without boiling, the juice speedily 
 ferments and becomes useless; but once boiled down 
 into gur, it may be kept for very long periods. The 
 juice which was at first brilliant and limpid, becomes 
 now a dark-brown, half-viscid, half-solid mass, and 
 
 [211] 
 
32 Field Museum of Natural History 
 
 when it is still warm, it is easily poured from the 
 boiling-pan into the earthenware pots in which it is 
 ordinarily kept. As it takes from seven to ten pints 
 of juice to produce one pint of gur or molasses, one 
 can calculate the amount of gur which a good tree can 
 produce in a season. One may count four and a half 
 months for the tapping season, or about sixty-seven 
 tapping nights. These, at five pints each, produce 
 335 pints of juice, which will give about forty pounds 
 of gur. 
 
 After the juice is boiled down into gur it is then 
 sold to the sugar-refiners and by them is manufac- 
 tured in various ways into different grades of sugar. 
 The best known is called dhulva, a soft, moist, powdery 
 sugar, used largely in the manufacture of native can- 
 dies. Another kind, termed pucka, is purer, granular, 
 and more expensive. The waste molasses, collected 
 during the preparation of sugar, is called chitiya gur. 
 When boiled for a longer time, it becomes a black, 
 sticky treacle, which is largely utilized for mixing 
 with tobacco for the native hookah, and also for mak- 
 ing cheap candy. A small proportion of the juice is 
 consumed as a drink either fermented or unfermented, 
 under the name of tari, or is converted into vinegar. 
 
 OTHER SUGARS 
 
 Malt sugar preparations. — A sweet material called 
 "ame" has been made in Japan since early times 
 from glutinous rice or glutinous millet, sometimes from 
 common rice and rarely from Indian corn or sweet po- 
 tatoes. Ame is made from these by converting their 
 starch into maltose by the action of an enzyme called 
 diastase. Sprouted barley is generally used to furnish 
 the enzyme. In making ame the grains or potatoes 
 are first cleaned, then soaked in water and steamed 
 until the starch grains are broken and made easily ac- 
 
 [212] 
 
Sugar and Sugar- Making 33 
 
 cessible to the enzyme. Powdered malt and water in 
 proper proportions are now added, and in six or eight 
 hours the diastase converts most of the starch into 
 dextrin and maltose. The liquid is then filtered and 
 evaporated to the desired consistency. One of the 
 forms is a dense, clear, light-colored amber liquid. 
 Another form is hard and quite similar to white candy 
 in appearance. Ame has been made in Japan for at 
 least two thousand years, and long before cane sugar 
 was known it was a favorite flavoring. Even at the 
 present time it is sometimes used instead of sugar in 
 cooking and it also makes a favorite addition to the 
 food of invalids. 
 
 Several malt preparations, some of them thick like 
 syrup and others more of the consistency of candy, are 
 on the market. These are mixtures of dextrin and 
 maltose coming from the action of diastase on starchy 
 materials. Many commercial products, such as those 
 called "predigested" and "malted," have this material 
 as their basis. 
 
 Glucose. — Glucose is manufactured in large 
 amounts in the United States from corn-starch, and is 
 sold for table syrup and other purposes. It is prepared 
 by a chemical process which consists of hydrolyzing 
 the starch into glucose by means of dilute acid and 
 pressure. Frequently part of the output of a glucose 
 plant is blended with maple syrup or other flavoring 
 material. The resulting mixtures are palatable and 
 nutritious but do not have the body-heating value nor 
 the sweetness of syrups having the same percentage of 
 cane, maple, and sorghum sugar. 
 
 Miscellaneous sugars. — Other sugars which before 
 1914 were largely or entirely imported, but which are 
 now made in the United States in amounts sufficient 
 for local needs, are lactose (milk sugar) used in the 
 preparation of infant foods, etc. ; levulose, used in place 
 
 [213] 
 
34 Field Museum op Natural History 
 
 of cane sugar in the foods of persons suffering from 
 diabetes, etc. ; and the so-called "rare" sugars, such as 
 maltose, mannose, xylose, melezitose, melibiose, treha- 
 lose, rhamnose, etc., used almost solely in chemical 
 and bacteriological investigations. The production of 
 these sugars varies from about 6,000,000 pounds in the 
 case of lactose to possibly less than one ounce in the 
 case of some of the rare sugars, and the price varies 
 from about twenty cents per pound in the case of lac- 
 tose to twenty-five dollars or more an ounce in the case 
 of certain of the rare sugars. 
 
 James B. McNair 
 
 Exhibits illustrating the processes of cane and beet sugar- 
 making, together with specimens of various sugars, are to be 
 found in the economic exhibits of the Department of Botany on 
 the south side of Hall 25 in the Museum. The various palms 
 mentioned are on the north side of the same Hall. A flower of 
 the "Boer Honey Pot" may be seen in the Hall of Plant Life 
 (Hall 29). 
 
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