MEETING OF THE MIDLAND COUNTIES SECTION, HELD. AT THE QUEEN'S HOTEL, BIRMINGHAM, ON MAY 15th, Mr. G. R. Burdass in the Chair, Sugar Manufacture.

Transcription

1 237 MEETING OF THE MIDLAND COUNTIES SECTION, HELD AT THE QUEEN'S HOTEL, BIRMINGHAM, ON MAY 15th, Mr. G. R. Burdass in the Chair, The following paper was read and discussed : Sugar Manufacture. By G. C. Evans. I propose in this paper dealing with two sugars of great interest to brewers, namely, dextrose or glucose and sucrose or cane sugar. Both these sugars are, as you are aware, very widely disseminated in nature. Both sugars in solution rotate the plane of polarised light to the right, though not to an oqual degree. Glucoset CoHioOfr reduces solutions of copper salts and of the salts of certain other metals, and it forms osazones when heated with phenylhydrazine acetate. Sucrose, C12H22O11, does not reduce metallic salts, nor does it form osazones. After being heated with acid when it is converted into a mixture of glucose and laevulose, known commercially as invert sugar, it exhibits both these properties. The two sugars, glucose and sucrose, have one property in common which is of interest to the brewer. When syrups mado from them are heated, they first colour slightly, and then acquire additional fulness, and it is this property that makes a hundredweight of sugar properly cooked of more value to the brewer than the same quantity of raw sugar. When the heating is continued water is lost, until at about 110 C. caramel commences to be formed, and the syrup becomes acid owing to the formation of certain decomposition products of the sugars. The substances included under the term caramel are of an extremely complex nature, and, although some workors have claimed to separate three substances from them, namely, caramelan, caramelen, and caramelin, these cannot at present be said to be well defined. On further heating charring occurs, and the product becomes insoluble. It is, of course, impossible within the limits of my paper to deal at all fully with the manufacture of these sugars, but my object is to present a pricis of the processes.

2 238 EVANS: SUGAR MANUFACTURE, We will now proceed to deal shortly with the manufacture of glucose as it occurs in commerce. It is made by the conversion of starch, such as that of maize, sago, rice, potato, manioc, etc. In America I believe maize starch is exclusively used. Manufacture of Starch It is the milling and preparation of the starch which is the major operation in the manufacture of glucose, and for which, as you will see, vast quantities of pure water are required. The maize, after cleaning, is steeped in large hopperbottomed vats for from 2 4 clays in water containing A 1 per cent, sulphurous acid (SO*), which is kept circulating by means of steam syphons, and at the same time heated to C. ( F.); this softens the grain, and at the same time removes soluble nitrogenous matter, oil, etc. The soaked grain is crushed in a Foss mill, the product being suspended in water and passed through a V-shaped tank, provided with a screw conveyer at the bottom and skimming paddles at the top, which skim off the germ which has risen owing to the oil it contains. These germs are cooked with live steam, the maize oil expressed, and the residue sold as cattle feed. The contents of the endosperm, starchy matters, bran, fibre, etc., pass on, and are thrown on to vibrating sieves, which retain all the coarse matter, allowing the suspended starch to pass through on to other vibrating sieves made of bolting cloth, and the residue left upon them is pressed, dried, and sold as corn bran, which contains quite a high percentage of fat (2'75 per cent.). The milky liquor, which now contains about 3*5 per cent, starch, and has a gravity of 3*5 Be*, is run into long wooden gutters 120 feet long, 18 inches wide, and 6 inches deep, in which the starch is practically completely deposited; the liquors enter at 3*5 Be*, at a speed of 1 gallon per 35 seconds, and leave at 0*5 Be*, at a speed of 1 gallon per 20 seconds; these liquors are settled, and the residue sold as cattle food The starch is made into a paste with water in large vats provided with stirrers and treated with dilute caustic soda solution of specific gravity 1,022, which dissolves oil and some gluten, and precipitates the rest of the gluten and proteins. After the liquors have been run off the starch is washed with water and separated from the precipitates by means of cocks set at different heights in the vat, from whence it is run once more to the settling gutters. You will see by the foregoing that upon the American principle of utilising everything nothing is wasted, in some cases even the first steep liquors are evaporated and the soluble contents sold as

3 EVANS: SUGAR MANUFACTURE. 239 cattle food; the remaining gluten has a variety of applications, being used, I believe, in patent foods, in stickfast materials, and enters into the composition of grease for tree banding, etc.* The starch' being now ready for conversion into glucose, and this is effected by means of 0*5 2 per cent, hydrochloric acid, under pressure in large copper autoclaves, the iodine test being used for the end point. Manufacture of Glucose, Formerly sulphuric acid was used, the con version being partly carried through in open vessels and then finished under pressure, but this process not only took a longer time but it necessitated the removal of the calcium sulphate after the acid was neutralised, and as this only comes out slowly upon concentration it meant two or three filtrations of heavy gravity syrups. The process of conversion can be so controlled that the resulting liquors contain higher or lower percentages of dextrin, as in the case of liquid glucose, where the conversion is carried out in about one hour at a pressure of 1 atmosphere (14*7 inches), the resulting product con* taining as high as 50 per cent, of dextrin, and being a non-crystallisable syrup. When the process is ended, the liquors are partly cooled and saturated with sulphuric dioxide in order to decolorise them, and also to prevent fermentation; they are then pressed, sometimes undergoing filtration through charcoal. Concentration is effected in triple effect evaporators and at inches B6 (1,400 specific gravity), the syrup is run into shallow tanks and seeded, when the whole solidifies in about three days. The mass is broken up and bagged, and is the finished product with which you are all familiar. As mentioned above, the process can be bo minutely controlled by means of time, tempera ture, quantity of acid used, etc., that the composition of the final product as to its percentages of dextrin, maltose, and dextrose are approximately known the so-called gallisin, which I believe to be a more or less indefinite compound, is of little use to the brewer; it is probably a conversion product of the cellulose tissues present in the starch. Glucose comes upon the market in more or less coloured lumps of Tho ftboro gives tho method for tho preparation of pure starch, but in the majority of cases it has been found unnecessary for tho manufacture of solid glucose to carry tho purification so far; tho gluten being separated from tho starch on the runs, and what is left is converted along with, it, requiring only a longer time. On the other hand, for starch syrup or liquid glucose, where colour is a consideration, more care is taken, not only with the raw materials, but throughout the process, even down to the artificial " whitening " with methyl violet at tho end.

4 240 EVANS: SUGAK MANUFACTURE. 70 and 80 per cent, strength, the former containing 81 per cent of total solids and the latter 88 per cent. The quantity imported into this country from U.S.A. amounts roughly to 160,000,000 lb. per annum. Liquid glucose, although very little used by the brewing trade, has a wide application in the manufacture of gkssery sweets and jam, jellies, etc. Sucrose. We now pass on to the manufacture of the better known sucrose, commonly known as cane sugar from its having first been obtained from this source, and here it would perhaps be as well to once again contradict the assertion which at one time made the public prefer cane sugar only, that the sucrose from one source is sweeter than from another; at one time when beet sugars were imperfectly purified, that may have been so, but it does not obtain to-day. A lot of misconception has arison through people tasting one size crystal sugar against another, and if you take coffee crystals, and taste this against a castor sugar, the latter will appear the sweeter simply because in its state of fine division it acts more quickly upon the palate. Again, in the case of Demararas the small percentage of molasses these contain have the same effect. The only way to compare the sweetness of one substance against another is to dilute them to extinction and then an accurate comparison can be made. Sugar is obtained from cane, beet, sorghum, palm, and maple, but it is only the two first which need concern us, and we will consider the manufacture of sugar from these seiialim. > There are several varieties of cane, the best known, perhaps, being the Bourbon and Java, and it has also a wide range thriving in almost all tropical countries, It contains on an average per cent, sucrose against per cent, in the sugar beet, and the average yield varies from 1A to as much as 5 tons per acre, at a pro-war cost as low as 65. Qd. per cwt. The canes, when they come to maturity, are cut and fed to the mills as soon as possible, in order not only to prevent fermentation, but also inversion of the sugar, which takes place owing to the presence of vegetable acids, and various moulds and bacteria. These mills are of the three-roller type, the cane being crushed between the first two, and the juice mostly expressed between Nos. 1 and 3. The rollers are smooth, but the cane in many cases receives a preliminary crushing between V-rollers the whole forming one unit. Maceration is often practised upon the resulting bagasse, the last juices from the mills being employed, but it cannot be carried too far, the cost of evaporation not

5 EVANS: 8U0AU MANUFACTURE. 241 covering the extra sugar recovered. The bagasse is burned under the boilers, the ashes being returned to the fields. Diffusion, so successful in extracting sugar from beet, has been tried with canes but has failed owing to substances of a colloidal nature being extracted, and the bagasse being left so wet that it will not burn unless undergoing a preliminary drying, and this in a country where coal is rather more expensive than it is hero, even at the moment, is a consideration. The clarification of the juico is still largely performed with lime alone, and although the more modern methods of carbonatation and sulphitation are coming into vogue, they have their special difficulties when applied to cane sugar, that of temperature being the greatest. The juice is run into steam jacketed pans and the lime added as a fine powder, the "tempering" aimed at being the exact neutralising of the free acids. The whole is raised to boiling and the fibrous particles, albumin and pectins come to the top as a scum known as the blanket scum, whilst the sand and heavier particles fall to the bottom, the clear juice being drawn from between the two. The amount of lime used is about 0*2 0*3 per cent. As regards the concentration of the syrups, the various grades of sugar met with on the market to-day are largely an outcome of these methods. Of the older ones the most interesting were firstly, the "teach" system, where the juice was evaporated in a series of open pans set on one fire, the syrup being ladled from one to another approaching always the fire, the striking teach being nearest, from whence the mass was transferred to hogsheads, and having set, the syrup was drained off through plug holes. Next of interest was "Fryer's Concretor," in which the juice was first made to flow down shallow trays heated by fire, leaving these at about 40 Be* (specific gravity 1,380). It was then conducted into a revolving cylinder, through which hot air was drawn, and left this as a moss which solidified upon cooling, ready for shipment. Then followed the vacuum evaporators whose name is legion, from the Yaryan quadruple effect which was horizontal and of very ingenious pattern, and the vertical triple and sometimes quadruple and quintuple effects, but whatever method has been employed we are under a great debt of gratitude to the cane industry for having done most of the pioneer work in the field of evaporation. During the concentration the syrups decrease in alkalinity owing mainly to disengagement of ammonia which gives rise to bad colours and may be corrected by the addition of soda, and another trouble which besets the manufacturer is the

6 242 EVANS : SUGAR MANUFACTURE. deposit of lime salts upon the tubes of the evaporators, impairing their efficiency. The syrup after concentration is run to a single vacuum pan where it is boiled to grain, i.e., until crystals of sugar come out, fresh syrup being admitted from time to time to help the growth. The molasses in the case of cane sugar are of value, the higher grades being fit for edible purposes and also for the manufacture of rum, whilst the lower grades are employed for the manufacture of commercial alcohol After the grain has formed and the mossecuit has left the pan the crystallisation is completed by cooling and the sugar separated from the molasses by centrifugals. I will now give a short account of beet sugar manufacture; this again will have to be somewhat sketchy as it is impossible to deal with the numerous details of the process. These, however, largely con* tribute to success or failure. It is to the shame of this country that we should be practically the only one in Europe which has no beet-sugar industry of its own, and this, in my opinion, is due largely to the apathy of successive Govern ments who cannot or will not see the obvious, which is in clear view to other people, leaving a potential industry to remain in darkness. I believe that a loan was granted at last in 1917 of some 50,000 to the British Beet Growers' Society, but owing to the war the scheme has had to lapse. I would point out that beet molasses is not fit for human con sumption owing to the salts and other impurities it contains, and that its two great uses are for cattle food and for the manufacture of commercial alcohol, and a beet-sugar industry would mean the setting up of a number of stills over the country if each sugar factory were to derive its full profit from its bye-products. I need not point out the advantages of cheap alcohol to the chemical industry, and also possibly as power for internal combustion engines, made from home grown materials instead of imported. The argument that it would ruin the sugar-growing colonies does not hold good, as they cannot at present, at all events, supply our own market and we cannot be expected to have much sympathy for those foreign countries from which much of the cane sugar of to-day comes. As a paying proposition and here it may be stated that the German factories average over 8 per cent, profit and as a benefit to the country at large, there can be no doubt. To the farmer, apart from its direct financial benefit, it compels a better cultivation, for the

7 EVANS : SUGAU MANUFACTURE. 243 beet requires dcop cultivation and proper and good manuring, which shows itself in subsequent crops, in evidenco of which the yield of corn has increased in Germany in 40 years per cent. (6 curt, per morgen to cwt.), and the land is enabled to carry a very much heavier head of cattle owing to the extra food provided in the shape of cossettes, etc. In addition, there is practically no loss, everything which is taken from the soil being returned to it in one form or another. On the other hand, it is useless to start with insufficient capital, or with an unsuitable site, as I believe was the case with the first factory in this country, or, to be correct, in Ireland, which was started in an old building situate in a swamp. The factory must be modern and equipped with the latest improvements; it must also be of sufficient size. Ware states that no factory should bo erocted to deal with less than 200 tons of beet per day, and each factory should farm at least 500 acres of its own, which at a time of short deliveries would bridge over the gap, and also serve as an example and experimental ground for neighbouring agriculturists. The Standard Cattle Company of Nebraska started in a very novel and practical way, in order to ascertain the quantity of beet with which they would have to deal. They planted the selected ground for one or two years with beet, which were fed to cattle, and so, after finding their yield, erected their factory. The discovery of sugar in the beet is credited to a German, one Andreas Marggraf, in 1747, but it may be said that to Napoleon the birth of the industry is due, for it was his "Continental Closure" which gave it the necessary fillip, and in which he afterwards took a practical interest, eventually erecting a factory upon his own estate. The yield of beetroot per acre of course varies, but may be said to average 10 tons, with a sugar-content of 13 per cent., but, as the farmer is paid upon the percentage of sugar his beets contain, it pays him to improve his cultivation to obtain a higher percentage. It also pays the manufacturer, as the sugar is easier to extract and contains less impurities. The factory is provided with silos, so that a reserve of roots may always be in hand to prevent a stoppage; these silos, which are covered sheds, are fitted with a central Hume, which floats the beets to the conveyers, and at the same time gives them a preliminary wash; they are previously topped, the leaves, which extract twice as much of the essential elements of fertility from the soil as the roots, being left upon the field for manure. They next pass through the washer,.

8 244 EVAKS: SUGAR MANUFACTURE. which consists of a perforated drum with revolving arms, forming a spiral, through which water is sprayed, and, as the beets are taxed upon their weight, they are next dried by means of brushes of whalebone or other material. They are next weighed for tax, and then go to the slicers, which as a rule consist of cylinders, at the bottom of which are fitted revolving discs, into which are screwed a number of knives. These require constant attention, for, despite numerous ingenious devices, stones and other foreign matter finds its way in and breaks or damages the blades. The slices, or cossettes, which are of three-corner or oval shape, fall into the conveyor, which is usually of the spiral form, and thence to the band or rake carrier, which is set above the diffusers, and into which it empties by means of hoppers. The diffusers, which are set up in batteries, numbering anything up to 16, are so arranged that the bottom of one communicates with the top of the next. They are of varying capacity, from 400 to 2,000 gallons, and are fitted with false bottoms and a manhole for the discharge of the exhausted cossettes, and at the top a valve to permit the escape of air and gases, and between each diffuser is the calorisator for reheating the juices as they pass from one diffuser to another, and which consists of a number of steam jacketed tubes. In working, the water at about C. is filled in from the top, and passes to the next diffuser in the series from the bottom, having extracted some of the sugar, and is reheated on its way, and so continues until it reaches the end unit, which has just been filled with slices, but here the circulation is reversed, the juice entering at the bottom pushes the air before it until it is full; the flow is then reversed and the juice drawn off. This last is called mashing. No. 1 is then cut out from the series, No. 2 becoming No. 1, the exhausted cossettes blown out with compressed air and immediately refilled. From this it will be seen that the process is continuous, and is really very simple. The exhausted cossettes, which contain some 0*25 per cent of sugar, and have a very high feeding value, are either sold wet after pressing, for feeding purposes, or dried and mixed with molasses. The volume of juice drawn off varies from 105 to 130 litres per 100 kilos, of beets sliced: it is cloudy and of a slight yellow colour, which rapidly darkens on exposure to the air. It is run firstly through rough strainers or pulp separators to the measuring tanks, and thence to the reheaters, where the temperature is raised to 90 C, and then receives the preliminary epuration with lime, the object

9 EVANS: SUGAR WANUFACTUKK. 245 being to precipitate the albumen, from which it is filtered, but in many cases this preliminary process is done away with, juices being submitted directly to the main action of lime. The action of the lime upon the raw juices is at the same time chemical and mechanical. Chemically, the lime precipitates and de composes the non-sugars, which consist chiefly of albuminoids and pectic substances, free acids, and acid salts, mainly oxalates and phos phates, whilst silica is almost entirely separated, many other compli cated actions and double decompositions take place, which if they do not eliminate non-sugars immediately do so during the subsequent saturation. Mechanically, it carries down a largo quantity of micro organisms, particles of beet, etc., by surrounding them in the pre cipitate. The mode of liming differs in the manner in which the lime is used such as (1) milk of limo, (2) quicklime in lumps, (3) in powder, (4) powdered slaked lime, and (5) saccharate of lime. Every method has its advantages and disadvantages, but the ones in most general use being milk of lime and quicklime in lumps. The saccharate is employed of course only in those factories that use this method of separating sugar from the molasses, to which I will refer later. As regards the quantity of lime used, this again fluctuates between wide limits from 0*75 up to as high as 3 per cent., and must be left largely to the skill of the operator; properly limed juices settle rapidly, the liquors being slightly cloudy and yellow in colour, and grey or dark-coloured juices show an insufficiency. The temperature is on an average 80, and the period of treatment about 15 minutes. The vessels used (defecators) being mostly made of iron, are provided with stirrers, and of course vary somewhat in construction, according to the method in which the lime is used; from here the juico flows to the carbonator tanks, which are again of iron, being usually square with a bottom sloping towards the exit. They are covered in at the top, with the exception of a chimney, and provided with a steam coil, and below this a perforated coil for the introduction of the carbonic acid gas. During the carbonatation many complex chemical actions take place, the solution becoming at first viscous, but this disappears as the process proceeds and the calcium carbonate is precipitated, the end point being when a titrution with sulphuric acid with phenolphthuline as indicators show an alka linity of from 0*07 O'l per cent. Upon the success of the carbonatation depends the subsequent filtration, for if this is bndly done, endless troubles occur, which mean not only loss of time but also loss of sugar. The juices from the carbonatation tanks are pumped either to waiting vol. xvi. 5. u

10 246 EVANS: SUGAIl MANUFACTUKE. tanks or direct to the presses, which are the same as the various types of filter presses as known in this country, but usually larger, some containing as many as 160 plates, and all are fitted with a reverse action, whereby the scums in the press are washed, these washings being known as sweet waters, and are used for the milk of lime in factories where this method is used. The cloths are usually of jute or hemp, these being found to stand better the action of the alkaline liquors, but the outlay in cloths, as may be imagined, is a considerable one. The scums from these presses are of con siderable value as manure, containing as they do practically all the essential elements of fertility extracted from the roots, including potash, phosphates, nitrogenous substances, calcium carbonate, iron, etc., and they are eagerly sought after by the fanners, being allotted often in the ratio of the beets grown. Following the filtration comes a second carbonatation or rather a mixed carbonatation and sulphitation, for ut this point the juice is saturated with sulphurous acid with or without a previous second liming, hut if this does take place it is only slight, not more than 0*25 0'5 per cent, of lime being added, the sulphurous acid acting in a dual rdle> both as a preservative and also as a bleaching agent follows again a second filtration with fine cloths, from which the juice emerges eyebright. The cumbersome and expensive process of filtration through char (bone black) has been almost completely eliminated, and although many other mechanical filters have been tried such as sand, Keiselguhr, wood wool, bark, etc., none of these are at the present time in general use, the filter press being found to give sufficiently good results when used alone. We now come to the third important stage in the manufacture of sugar, that of evaporation, about which much could be written with reference to the types of plant used, their efficiency, heating surface, steam used, etc., all of which involves many intricate calculations, which I do not propose to enter into. Suffice it to say that the juice is evaporated in multiple effect apparatus, consisting of three or more closed pans, working under reduced pressure, being provided, of course, with condensers, and wet or dry vacuum pumps, and from these the syrup is pumped to the graining pan, where the sugar crystals are actually formed, this again is a vacuum pan, but a single effect. Their shape and size is legion but it is important in all that there should be good circulation, so that the crystals once formed should grow evenly, and that no one part of the pan is hotter than another. They are heated in the first place with

11 EVANS: SUGAR MANUFACTURE, 247 the vapour from the multiple effect or exhaust steam, but as concen tration increases so must the temperature, which necessitates the use of high pressure live steam they are fitted with numerous well lighted view holes, thermometer, proof stick and sample cocks and the man in charge is more or less an expert. The object is, of course, to obtain as large a quantity as possible of good-sized crystals, and this is accom plished by evaporating the first bulk until it is sufficiently concentrated, that is to say, the solution becomes supersaturated and so throws out crystals even at high temperature, when fresh syrup at lower tem perature is introduced, but here the art of the man in charge comes in, for if too high a degree of supersaturation is obtained then very small crystals are the result and from these a good grain cannot be built. At the right moment when good grains are formed more syrup is drawn into the pan and as this concentrates so it builds on to the original crystals, and this is continued until the strike is complete. Numerous factors govern the conditions of a successful strike, such as purity of syrup, which alters the point of supersaturation, temperature, degree of vacuum, time, etc., and all these have to be taken into consideration. At the time when the strike is complete the massecuit has sufficiently tightened, the water content is about 5 per cent, and it is then run to the crystallisers-tanks where it is allowed to cool for some 15 hours, broken up in mixers and thence conveyed to the centrifugals, where the syrups are swung away from the crystal sugar, which is then bagged, cooled and sent to store. This cooling is essential for otherwise inversion is set up and the sugar becomes discoloured. The syrups or after products are thon worked for a second crop of sugar, being again heated and evaporated and run to tanks, where it is seeded and crystallised in motion by means of stirrers, the object being that while the heavy syrups are cooled they are at the same time turned over, so that an even growth of the crystals is ensured. Many attempts have boon made to purify these after products such as by sulphuring, filtration, etc., but none havo been a success. The mass is swung out in centrifugals, being in some cases cured with steam at the same time. These second-grade sugars are used for refining and are also in some cases dissolved in the carbonated juices and put back into the main process. We are now left with the final molasses. In most European countries before the war the molasses contained less than 50 per cent, of sugar. To recover this sugar recourse is had to certain indirect methods: (1) Osmosis, (2) Elution, (3) Substitution and separation, by lime or strontia. u 2

12 248 EVANS: SUGAR MANUFACTURE. The first process depends upon the fact that, when two liquids that will readily mix are separated by a porous membrane, pressure is exerted, and the molecules pass through the pores from one liquid to the other; this in practice is carried out in an apparatus similar to a filter press, the chambers being separated by parchment paper. The molasses enters one frame and the water the next, flowing in opposite directions, during which the salts from the molasses pass through the membrane into the water, which at the same time dilutes the molasses, on the other side, tho How of the two liquids being regulated by hydrometer readings as they leave the osmogenc. These osmoscd molasses are grained in pan and crystallised in the same way as second products. The only other method which we need consider, and the one most extensively employed, is that of separation, which consists in the formation of a tri-calcic saccharate, and its separation by filtration, the mother liquors containing all the impurities. This saccharate, which contains per cent, sugar, is diluted to a milk, and is used in the purification of the juices from the diffusers. Finally, we will briefly consider the purification or manufacture of white sugar, for which the starting point is the sugars of the first crystallisation, which are washed in the centrifugals after the molasses has been swung out, either with water, or steam, or cleare, which is a white sugar syrup, sometimes a combination of two being used one after the other; in other cases the sugar is packed into boxes, which receive a succession of cleares rising in purity, as many as 32 cleares being used, the resulting sugar polarising as high as 99*8 per cent. The sugars are dried in revolving drums, through which a stream of hot air is drawn, thereby eliminating all moisture from the crystals, which fall from the end into the rotating sugar sifter, which grades the crystals and separates the dust. Each factory, of course, has its own limekiln constructed according to the particular fancy of the manager, some with outside hearths, somo with inside firing, and it is, of course, from these that tho CO* for the carbonation is obtained, great care being taken to wash the gas and obtain it in as pure a form as possible. Many are the micro-organisms met with in tho process, which is not surprising seeing that the raw material is derived straight from the soil. There are some 3,300,000 micro-organisms por cubic cen timetre in the diffusion juices, and these include many well known, such as Leuconostm mesenteroides, which produces ropiness, and many acid-producing organisms. There are also some organisms which

13 EVANS: SUGAR MANUFACTUKE. 249 invert sugar, owing to tbo secretion of invertase, but these are practically all eliminated during tbo liming, only a few passing on in spore form, but which may, nevertheless, cause trouble if not watched. I will now give a few statistics which are of interest, the first being of the 1900 campaign of the Culm see Factory in Germany : Total area cultivated in beets for the factory (acres) 12,773 Beet?, sliced (tons) 117,000 Duration of campaign, (days) 59 Weight of beets worked per day 2,308 Sugar extracted (tons) 18,776 Besiduary molasses (tons) 2,735 Prico beets per ton (with supplementary grant propor tion to profits) 21*. Total receipts 199,108 Expenses for beets 124,213 Cost of manufacture, including wages 44,583 Netpro6t 30*312 This means a profit of 20 per cent, on capital, notwithstanding that in this year the price of both coal and wages had risen, and that of sugar was low on the market. I will now quote a few figures of the English-grown beets taken from the reports of Messrs. Orwin and Orr, as given in the Journal of (he Boanl of Agriculture. These beets were grown in Norfolk and Suffolk, and comprised 11 lots, from 70 acres down to 2; the average cost of cultivation, which included ploughing, cultivating, harrowing, etc., labour, manure, seed, rent and rates, was 8 3>\ hi, per acre. Yield of roots per acre, 9 tons 15 cwts. This figure is deceptive, as in three cases the yield was only just over 8 tons, which brings down the average, which otherwise would be nearly 12 tons per acre. Total cost of washed beets, after adding haulage and railway charges, 1 0s. 1 hi per ton. Profit to farmer: per acre, «11 Us. 5^/.; per ton, 1 Is. lorf. The feeding on the tops left on the field was let at 205. per acre, and in one case the farmer kept 300 ewes three months on 25 acres of the same feed. The above figures were for the season 1914, which, it will be remembered, was dry and unfavourable for root crops, whereas the results of 21 trials in 1906 gave a yield of 14} tons per acre, with a sugar content of 16J- per cent., which compares very favourably with any grown upon the Continent, where it might be mentioned there

14 250 DISCUSSION. are 1,240 factories producing prior to the war 8,163,200 tons of raw sugar per annum. Discussion. Mr. W. Scott said that the paper had brought back memories of his association with sugar manufacture in one of the West Indian colonies, where he had to do with the manufacture of cane 6Ugar. In those days nobody on the estate knew very much about the chemical action which takes place in connection with the manufacture of sugar. At that time the German bounty system was practi^lly killing the sugar industry of the West Indies, and it was only kept in operation with the object of keeping the estate together. The Company was growing coffee, cocoa, and limes, and distilling rum, and, in fact, doing any kind of trade they could. Sugar production was only carried on for the purpose of providing something for the works to do until the Company's plots reached the bearing stage. Under these circum stances sugar manufacture was carried on in a very crude manner. His duties as an overseer were mainly with the natives, a very important part being to stop them from stealing tho sugar. It was the practice to let out certain plots of land to the natives to be cultivated. The Company provided the cuttings of the cane which the natives had to plant and to keep weeded. It was his duty to manure the ground, which was generally done by the replacing of the leaves, which served as an excellent and natural manure. The Company provided the transport, and boiled the sugar for the planter, thus producing crude sugar. The man took two-thirds of the proceeds, the estate taking the other third. The overseer had to sit through the night superintending the process, which consisted of crushing the canes through three roller mills which were worked by a water wheel. At times, the river would " come down " and start that wheel at such a terrific pace that nobody could stop it, and the result would be the wreck of the machinery. The wheel was about 30 feet in diameter. That was one of the little difficulties they had to contend with. As Mr. Evans had explained, on the wall were arranged a lot of pans gradually diminish ing in size to allow for the concentration of the liquid. That process waa the most important of all, and they had to have a reliable boilerman, and really the whole success of the operation depended upon the boilerman knowing when to " strike/1 and also as to what quantity of lime was necessary to neutralise the acids of the cane juice. This man was a great official, and had his own idea as to how this work should bo done. The lime was got from coral brought from Barbadoes, which

15 DISCUSSION. 251 was a coral island. The island whore he was engaged was of volcanic origin, and so they were unable to find any lime there. The boilerman decided the important question left to him by the application of a number of tests peculiarly his own, and so determined when the process had to be struck. His methods were very crude, but the duty was very important, because if he did not happen to strike at the right time, they would get nothing but molasses, and the sugar would not crystallise out. If he was successful the concentrated syrup would " set" in the cooler, and was dug out and put into casks drilled with a lot of holes to allow the molasses to drain away. The molasses were applied to various uses by the natives. Sometimes they would decide to take their share in syrup instead of in sugar, and then came the overseer's task of measuring out the syrup in cans. The people came with American paraffin tins on their heads, and the unfortunate over seer had to watch them most carefully or he would get done. At the works very peculiar things were found at the bottom of the pans when they were emptied. There would be yams, bananas, and cocoanuts, which had been thrown in to absorb the sugar. These they would fish out afterwards and consume with relish. Sometimes the syrup was converted into rum by fermentation and distillation. Fermentation was carried through in a peculiar way. The natives had no idea of yeast or anything of that kind, and they used to keep the syrup diluted with water and throw in a lot of branches of the guava tree. There were certain yeasts on the loaves of that tree which served to start the fermentation. A policeman used to act as exciseman, and he imitated, to a certain extent, the operations of the excisemen in England. The natives had a great preference for the spirit as it ran from the still, and they could imagine the condition of the black police man after the stuff had been running for a few hours. There was a lot of illicit distilling of rum, but they had an old Lifeguardstnan as chief of police who prided himself on the fact that he could always distinguish on what estate any rum had been distilled. There was not a rum put on the market but he could tell by his palate where it came from, so he imagined. The planters used a still for all sorts of things, such as distilling limes, or distilling bay leaves for bay rhums used by the barbers. The official would know who had been distilling bay and who had been distilling limes. Then he would say, " There is a slight trace of tho bay leaf who has been distilling bay loaves recently "? He would then consult the excise books for that estate, and if he found no recent entries, his suspicions would be aroused. Mr. Evans had not referred to brewers' sugars very much, though they all knew that

16 252 DISCUSSION. he knew enough about it. The brewers, on the other hand, during the war had had to take whatever they could get hold of, both in regard to quality and quantity, and he thought that, as a result, they had picked up a few hints. In fact, practical experience had been forced upon them. Anybody who had been through the experience of the war must feel that he had come out of it a little wiser through having to use these things. Possibly, on a future occasion, they would have something original from Mr. Evans touching upon brewers' sugars and their problems, which would be very welcome. Mr. R. H. Hopkins inquired whether there was any reason why maize starch used in the manufacture of glucose should give better results than other starches. He understood Mr. Evans to say that American maize yielded better glucose than anything else. Personally he should have thought that potato or some of the starches with bigger granules would have given better results, thus, for example, the celulose wall having been broken, there would be a larger propor tion of granulose in potato than in maize, and in consequence, maize Btarches would not give such good results as those of potatoes. He should have thought that the essential matter was the soluble starch content of the grain, and that would be the deciding factor. Mr. W. C. Short inquired whether the author had any experience of the liquid glucose crystallising out on keeping. The Chairman said some very useful figures had been presented. He had in mind the same question which had been put by Mr. Hopkins as to why maize glucose was to be preferred, because he had been given to understand that the starches obtained from rice and sago and similar products were equally pure, and he should have supposed that the glucose manufactured from those would have been quite equal to maize glucose. Another figure put before them by Mr. Evans related to importations from America. They were told that they obtained 160,000,000 1b. weight of sugar from America every year. That certainly seemed a very large importation. With regard to beet cultivation, several experiments had been made in this country. Mr. Evans quoted the figure of 8 per cent, as representing the profit on the German enterprise. That appeared to him (the speaker) a very poor return on the cultivation of the land, and he thought the British farmer would not be very well content with an 8 per cent, return on his money. Mr. Evans had also mentioned the maintenance of 300 ewes on a farm devpted to beet cultivation. That was not very clear, and he would liked to have it explained how these animals were maintained. Were they fed by the residuals obtained from the

17 DISCUSSION. 253 beet, or would the beet be sliced up and mixed with other materials for the feeding of the ewes 1 Other German figures related to acreage. He understood that 12,773 acres of land were used for beet cultiva tion in the way of German farms, and they yielded 2,380 tons per day throughout the year. It seemed to him that if they cultivated beet root to that huge extent on one soil, the land must be exhausted. Supposing they went on producing the same crop year by year. He should have thought it would be better to cultivate a portion of the farm with beetroot and then change the crop. The English practice was to cultivate on a four-course system, varying the crop each year. Certainly if they went on continuously cultivating on the same land beet year after year they must occasionally get rather bad results. Mr. Evans did not indicate whether anything else was grown on the beet farms. Then there were practical difficulties. It was rather obvious that the beet would have to be sown at a certain time of the year, and it must involve a huge problem to get all the land cultivated practically at the same time, so that a good deal of labour must be available, and as beet made a fairly quick growth, it must furnish another problem as to what was to be done with the labour during the other part of the year. Mr. Evans, replying to the discussion, said that he would like to explain with regard to the 8 per cent, profit that this was the average profit on all factories in Germany, and not the profit of the farmer. The factories themselves did not cultivate all the beet they used. The usual method was to erect the factory in the middle of a farming district, and the farmers of the surrounding district supplied the factories with the beet receiving in return as part payment, scums for manuring and cossettes for feeding purposes. With regard to the rotation of the crops, the farmer was in the habit of rotating his crops in the same way as in England but instead of growing mangolds and swedes for his cattle he would grow beet. He got the cossettes back from the factory and fed his cattle with them. With regard to the ewes he took the figures from statistics given by Messrs. Orwin and Orr in the Journal of the Board of Agriculture. These animals were fed on the tops cut from the beet plants. When the leaves wore cut off they were left on the farm so as to save labour and carriage to the factory ; it was on these tops and on the cossettes that the ewes were fed. With regard to the 2,808 tons of beet worked per day they related to one of the largest factories in Germany. It was an important point to remember that the factories did not themselves engage in the growing of beet to any large extent. That beet was supplied to them by the

18 254 DISCUSSION. neighbouring farmers who were paid on tho weight of sugar contained in the beet, and not on the weight of the beets themselves. That, of course, entailed a certain amount of analytical work, but it was certainly better from the cultivator's point of view because a good cultivator would obtain a larger percentage of sugar than a bad cultivator. The factory as a rule, supplied the seed to the farmer and all that seed was most carefully selected. In fact, beets were tested for their sugar-bearing qualities and then selected for seed, the poorer qualities being rejected. As indicating the benefit to the land accruing from cultivating beets, he might point out that the increase in the production of wheat in Germany in the course of 40 years was from 250 to 300 per cent. As a matter of fact, the average British farmer knew but little about the kind and quantity of manures required for his land. He merely concluded that a certain field required slag, and he put on a lot of slag regardless whether the soil was high in phosphates or not. He had had a little experience in that direction and it was a mystery to him why the farmer should throw good money on to his land without any actual knowledge of what was required. It was a fact that the market gardener got a good deal more off his land per acre than the farmer. Much more frequently the market gardener would have an analysis made of his soil, and the analyst would tell him exactly what the soil required for the growing of his crops, and in that way a lot of money was saved in manures. If the farmer would follow that example he would save himself a lot of useless expense. It was a very common thing for a farmer to keep manure heaps in his field for four or five years in succession with the result that when he came to use the manure about 50 per cent of the nutriment was gone. He understood that liquid glucose was used in this country for dilutions of honey and the making of glassy sweets as well as in jam factories and in the making of jellies. It was also largely used in American breweries. He had never yet had any experience with liquid glucose crystallising out. If anything of that kind happened it showed that it had been converted too far, in other words, the percentage of dextrine had fallen too low and had been converted into dextrose, which crystallised out. Haziness is also often due to calcium and other salts crystal lising out, and sometimes to yeast and other bacterial infection. With regard to maize glucose being better than that made from other starches, he could only speak from experience. He had had a very considerable experience in the boiling of glucose, both for the manu facture of primings and brewing sugars and also for the manufacture of caramels. It was a most extraordinary fact, but for some reason

19 PRODUCTION OF GLYCBRIN PUOM MOLASSES. 255 which he could not quite explain, it almost invariably had a bitter taste when heated up to a certain temperature. He put it down to the starch used as the raw product and the impurities it contained. The maize glucose never acted in that way, and it maintained its sweetening properties right through. With regard to the brewing sugars which had been used during the war, as they were aware, he had been connected with the brewing material side of the business, and any manufacturer of brewing materials must admit that the sugar had been very bad during the war; but that was not the fault of the manufacturers. No doubt the brewers had had troubles of their own, but if they knew the troubles the makers of brewing materials had had in producing any brewing sugars at all they would be surprised. They had had the most fearful raw materials foisted upon them. The experience had been most trying, but the thing which most astonished him was that the brewers had not complained about it. They had, in fact, been very good in that respect, as the makers of brewing materials had practically had no complaints. With regard to the manufacture of rum, and particularly as to the yeast used, he had lately been doing some work in regard to yeast in the way of fermenting different materials, and it was very extraordinary how sensitive were these yeasts in regard to the percentage of alcohol they produced. As they were all aware, yeast would only produce a certain amount of alcohol, and then it would curl up. Each type of yeast would produce its own per centage and no more. Ho had had experience of one yeast used for the fermenting of different wines. This yeast was introduced from Oporto. He had found that if the yeast was recultivated in suitable material it reverted to typo and again became vigorous. A hearty vote of thanks was accorded the author, on the motion of the Chairman, seconded by Mr. Short. Production of Glycerin from Molasses* Pasteur, in 1858, observed that glycerin in small quantities is invariably found among the products of fermentation of sugars by yeast, and there is reason for believing that, unlike certain other secondary products which occur in fermented worts and musts, Abridged from an article by Arthur R. Ling in the Journal of the Society of Chemical Industry, 1919, 88, It.