tain degree of success, but it has scarcely found its way into the Cuban Yngenio, whatever use may be made of it by the sugar-refiners of England and the United States. There are other means of clarifying the "guarapo" and of discharging the molasses from the sugar, which should only be used by men well acquainted with chemistry, as they require the employment of poisonous acids. These, therefore, do not concern the sugar-planter or manufacturer of clayed sugars, but belong properly to the more scientific refiner.

a later stage. In the Yngenios using Derosne's condensadores it is observed that they obtain the best sugar when they take the greatest pains to keep the machinery scrupulously clean, and any carelessness in this respect, especially if it occurs at this stage, is sure to injure the quality. In this matter the San Martin is a model establishment. After long trial some sugar-masters have ceased dropping sirup over the condensadores; but by dropping water instead they still use them as condensers for the waste steam from the vacuum-pans. On the whole, a steam injection column (which is also attached to Derosne's machinery) would seem to answer the purpose better, taking less room, and doing away with the objectionable vapor. Another very serious objection to Derosne's condensadores is their liability to cracking when much worn. Fine holes as small as the head of a pin and little

machine enveloped in clouds of steam, and little leaks like these very much interfere with the vacuum in the pans.

After passing over the condensadores—or, directly from the first filters where condensadores are not in use-the sirup passes into the first vacuum-pans.

The principle of the vacuum-pan is well understood. In them the same processes of boiling and evaporation are performed which we have already described in the open or Jamaica train, but at a much lower temperature, and without risk of burning the sugar. The loss by evaporation in the open train is also avoided. This loss is considerable, owing to the violent tossing it undergoes in the open air. In the first vacuum-pans the boiling is slow, and sugar is not formed in them, the object being to increase the density of the sirup by evaporating a part of the water composing it, after which it has to undergo further clarifying before it is boiled

After passing through the smaller of the two kinds of carbon-filters in the San Martin, the juice-el guarapo-passes over a series of pipes called condensadores, which perform the double function of condensing the steam rising in the vacuum-pans and of evaporating the juice. The oretically this machine is an exceedingly ingenious adjustment, and constitutes the distinguish-cracks in the joints are not easily found in a ing feature of the Derosne train; but practically it has many objections. It is formed of horizontal pipes about six inches in diameter, arranged in a tall rack, and turning so sharply that they are parallel, one above the other, at a distance of not more than three inches apart. From twenty to twenty-three of these turns occur in each machine, so that at a distance it looks like a rack of parallel bars arranged horizontally. The juice is carried to the top of the frame, and falls through fine holes, which discharge a drop at a time. Falling upon the hot pipes it condenses the steam within, and loses some of its own liquid, which rises in a dense vapor. It does not remain long enough on each pipe to become burned, and in the fraction of a second occupied in its passage from one pipe to another it loses heat to the atmosphere. Near the bottom there is more risk of burning the sirup; but here again the steam in the pipe has lost much of its heat, and as the liquor becomes hotter the pipe is cooler, a nice equilib-down into sugar. The usual form of Derosne's rium being maintained by the relative action of the two. Now this is all very well as long as the pipes are kept clean and the liquor runs over them in an unbroken shower of small drops as regular as the teeth of a comb; but, unfortunately, as soon as the mill is stopped the copper pipe is covered with a rusty coat, and looks more like sand-paper than a tube of polished copper. It is then necessary to clean it carefully by dropping water over it for some time before and after using it; and even with the greatest care it will be noticed that in many places three or four drops will run together, and the action become irregular. When once the sirup has formed little channel-ways for itself in this manner it is exceedingly difficult to obtain good action, and the sirup is injured. It will be readily seen, too, that the constant action of minute drops of sirup or water must very soon wear out the copper.

Besides these defects, there is grave objection to the constant clouds of steam which it throws off, filling the boiling-house with moisture, and interfering with the crystallizing of the sugar at

vacuum train is what is called double-effect; that is, two pans stand side by side, one of which is boiled by the steam rising from the sirup in the other, the sirup also being drawn, at intervals, from the first to the second. In the San Martin they possess two trains of three pans each, the middle pan being slightly the largest, and discharging its steam into both the others. In some places a treble-effect has been tried, the first pan boiling the second, and the steam from that second pan boiling the third; but it is found that too much heat is lost by this plan. The art of boiling sugar in a vacuum-pan requires quite as much skill and experience as in the open train, the proof by teache-or touch-being the same in both instances. The sirup to be tried is drawn by a simple and ingenious proofstick from the very centre of the pan, and is tested either by teache or by Baume's saccharometer. This is a tube of mercury or fine shot in a bulb like a thermometer, but, unlike the thermometer, containing atmospheric air. In water it sinks, but in sirup it rises in proportion to the density of the sirup. A degree on the scale

marks 0.019 parts of sugar in the sirup. if the saccharometer, floating in sirup, marks 10° B. we have .019 × 10.19, and know that there is nineteen per cent. of sugar in that sirup. If the sirup is boiling, however, it is denser than when cold by about three degrees; but thin juice is of the same density, hot or cold. Although these distinctions are not often known to the solemn-faced Asiatics or darkeys who use this beautiful little instrument, they are able to get as much practical good from it as the sugarmaster himself, the latter having made a mark upon it for their guidance. The skill lies in admitting thin juice, or guarapo, from the reser-general plan of the casa de purga is the same voir, or from the other pans when the sirup be- on all the estates, there being one floor pierced comes too thick; and when the panful is prop- for the cones, and a packing and drying room erly "cooked," or brought to a density ranging below. In the lower room are double rows of from 26° to 28 B., where it is about half sugar, cars, one above the other, placed on tram-ways, to discharge it promptly into the caldrons for and so arranged that they may be run out into further defecation. The same heat to which the sunshine with their loads of moist sugar to the sirup had been subjected in the vacuum- dry. This plan of building is simple and effectpans is kept up in these by means of a steam- ive, and could not be improved. The white coil at the bottom, into which the operator ad-sugar, or blanco, when dried in the sun is ready mits steam at will. Just enough steam is ad- for market. The quebrado requires a little more mitted to bring the liquor to a froth; very little time, and is spread over an oven; but the cuvapor arises from the caldron, and the instant guchos, or points of the cones, are brought back it does the steam is turned off. Each time that to the boiling-house, ground up thoroughly, it is brought to the boiling-point it throws up moistened with water, and passed through the with the froth some of the impurities which centrifugal machines to free them from molasnone of the former processes had removed, and ses. The sugar is now of the grade of quethese are lightly skimmed off as they arise. brado; or being further moistened with water, and placed in panes it may be brought again to the purging-house and regularly clayed, making good white sugar, although not of as good quality as first sugar. The smaller quantity obtained will not generally pay for the extra labor.

Thus was first heated; the thick molasses is stirred freely, and speedily carried from thence to the ordinary sugar-cones, or panes, where it stands for a day in the high temperature of the boilinghouse until the crystals acquire some solidity. The panes are then removed to the casa de purga, where they undergo the claying process, and are purged of their molasses. This process is the same on estates using the Jamaica train, and needs no further notice. The casa de purga is generally the largest house on the estate. That of the San Martin is 400 feet long and 150 feet broad, and contains room for 22,220 panes. The

The process is repeated again and again, and the sirup is not only purified but concentrated. It is now turned off into the high filters, where the last process of clarifying is performed. From these it runs out a clear bright liquor, as pleasant to the eye as fine old sherry. This pure liquor, which has been round and round the boiling- The molasses that drips from the panes in the house so many times, now finds its way into the casa de purga is collected in tanks and returned great vacuum-pan, called the strike-pan, where at to the boiling-house, when it is taken up by the last it will become sugar. Here it is boiled at the vacuum-pan and boiled again, making very good temperature of 180° F.; but gradually as the sir- sugar; but this time, instead of being placed in up becomes thicker the temperature is lowered panes to make clayed sugar, it is run into shaluntil, when the crystals have began to form, the low iron tanks, about ten by four feet, in which heat is not greater than 160° F. The reduc- the crystallization proceeds more slowly than in tion still goes on until, finally, when the sirup the former. When the sugar in these has hardis ready for "striking," the temperature is the ened it is cut out by coolies with spades, worked lowest at which proof-sugar will boil at three until it is a thick paste of sugar and molasses, inches below a perfect vacuum, say 145° F. It and poured into the centrifugal drying-machines, is now thick with crystals of sugar floating in with which all large Yngenios are furnished. molasses, and the trial by teache is repeated These are of various patterns, prominent among momentarily. The engineer peers anxiously them being those of J. F. Cail and Co. of Paris, through the glass-windows at the boiling sirup, Aspinwall and Woollys of the United States, and and finally makes preparations to discharge his Fawcett, Preston, and Co. of Liverpool. The Ynpan into the "heaters" below. The sirup falls genio San Martin has fifteen of the first-named from the bottom of the strike-pan of a rich au- manufacture. Cail's centrifugal, although very burn color, and often the crystals can be seen as good, is not so easily managed as the others, it flows. The strike-pan, or great vacuum-pan especially the machine made by Fawcett, Presof the Yngenio San Martin, is a magnificent ton, and Co. The power is communicated from piece of workmanship, costing $70,000, and ca- above by common shafting in the French mapable of boiling from 1100 to 1500 panes or chine, and from below in the American; othcones of sugar, containing 100 pounds each of erwise the two are very similar. The American green sugar, in a day. method leaves the top of the centrifugal unencumbered by machinery, and facilitates the operation of supplying it with molasses. It also gives the laborer more room when scooping

In the heaters below the strike-pan steam is applied by means of a cast-iron jacket, such as we saw around the defecadores where the juice

THE COOLING TANKS.

out the sugar than in the French arrangement. These are the only distinctions between the French and American systems. In both the machines are charged before they are set in motion. Revolving with great rapidity, the molasses is speedily thrown by centrifugal force to the sides, which are made of wire netting, corrugated for greater strength. The molasses flies off through the meshes of this netting, leaving, in six or eight minutes, a fine, dry sugar, called miel de purga-the common brown sugar of the grocers. The grain is finer than that of the sugar made from the first boiling of the sirup; and this quality of sugar can be afforded at a low price. The color is regulated according to desire by running the centrifugal machine for a longer or shorter period with each charge of molasses; and when a whitish sugar is wanted, it is obtained by turning a jet of steam upon the revolving mass. The bleaching effect of steam is well known. The use of steam, however, causes it to part with so much of the molasses that it loses weight, and the higher price of the whiter sugar rarely compensates the planter for the loss. It is therefore customary to turn on the steam for only a minute or two before stopping the machine, causing a crust of white sugar about a quarter of an inch thick to form on the two or three inches of miel de purga which clings to the sides of the machine. As each machine can be thrown out of gear without interfering with the others all stages of drying can be observed at once. The molasses from this second purging is boiled and passed again through the centrifugal machines, so that the common "third" molasses of commerce contains little crystallizable sugar.

tirely, except in principle, from both the others named. Instead of being set with vertical shafting, as those are, it is hung like a coach-wheel, on horizontal shafting, two machines being generally hung on one shaft, but each being thrown out of gear at pleasure, independently of the other. Instead of being two feet in diameter, it measures four; and instead of being charged while at rest, the molasses is run into it by a trough while in rapid motion. Being of I larger size, and requiring no increase of power to turn it, its makers claim that it is more economical, and justly so in our opinion. With six-horse power it can clean 400 pounds of sugar in an hour. It is supplied with a small steam-pipe, to be used in bleaching if desired. The brakes used in these three machines all differ slightly; but this is of no importance, as all are excellent. Probably there is less friction with the English brake, owing to the peculiar hanging of the machinery.

On many of the sugar estates, when the owners can not afford the costly copper vacuumpans and the amount of machinery and charcoal filters which accompany them, it is not unusual to find the old Jamaica train used with a Wetzel pan, or that invented by M. Bour, to concentrate the molasses. Sometimes a small vacuum-pan of the Rillieux patent is used for this purpose, and the molasses purged, finally, in a few centrifugal machines connected with it.

The Wetzel pan is heated by steam. It is a long tank, the bottom being rounded to form the half of a circle. In this tank, which is filled with molasses, revolves a hollow wheel, through which steam passes freely. The hollow drums of this wheel are also full of steam, and placed at either end of the tank, revolving in the molasses. Through their centres passes a large pipe, also steam-filled; and the circumference of these two drums are connected by pipes, about an inch and a half in diameter and two inches apart. Revolving slowly, a considerable heating surface is thus presented to the molasses; and each of the smaller pipes, as it rises from the liquid, carries a considerable quantity with it, which is dripping throughout its semi-revolution, until it plunges again into the molasses. The whole mass of molasses in the tank is genThe English centrifugal machine differs en-tly agitated by the constant revolution of the

machine, and is concentrated rapidly, much | each eleven feet long, have respectively 240,

more so than over an open fire, but without risk of burning.

The Bour pan is similar in principle to the Wetzel, the only difference being that the liquid is distributed equally over a number of drums similar to those at the ends of the Wetzel tank. The Rillieux vacuum-pan is of cast-iron, and differs in shape from the copper pans of other makers, the pipes being set horizontally instead of vertically, as in the dome-shaped vacuum-pan. The lower half of the Rillieux pan is filled with pipes an inch and a half in diameter, laid lengthwise, as in the boiler of a locomotive; the upper half is filled with sirup and the steam arising from it. The use of iron instead of copper very much reduces the cost, and makes the pan popular for boiling miel de purga in small mills, the same steam-engine giving power to the centrifugals. The only drawback to the use of this economical system is the difficulty of cleaning iron pipes and preventing corrosion.

There are in Cuba, as well as in Louisiana, estates of from fifteen hundred to two thousand acres of cane which use Rillieux's train, greatly to their satisfaction. It is simpler and less costly than that of Derosne, or any other on the same general system as Derosne's, dispensing with the condensadores, which are of questionable advantage in that system, and substituting a steam injection-column. For a complete train under the system of Rillieux three pans are required; but, as they stand side by side, and as their shape allows great compactness with large heating surface, they require fewer boilers than the same number of pans under other circum

stances.

354, and 260 pipes of 14 inch diameter. The sugar made by this estate is excellent. That of the adjacent plantation, Santa Elena, with similar machinery, is also of superior quality. A new mill at Bolondron, called the San Rafael, has been recently fitted with the Rillieux machinery, and here the system may be studied with the greatest advantage. The sugar of this mill is of very good quality.

It does not always follow, however, that the Yngenio possessing the finest machinery makes the best sugar. This is notably illustrated in the neighborhood of Banagüises, where the adjacent estates of "Habana" and "Álava” differ greatly in the quality of their refined sugar. The "Habana" has the reputation of making the best in Cuba; and as the two estates are the property of the same gentleman, Señor Zulueta, one of the richest sugar-planters on the island, and master of we know not how many Yngenios and cabellarias of land, it might be expected that any talent possessed in the one Yngenio would be exerted to improve the other, or that if there was any decided advantage in machinery enjoyed by the one it would be introduced into the other. It is certainly not for want of fine machinery that the sugar of the “Alava" is not the best; for the machinery of the "Alava" is the newest and best of the two, and the estate has in its time turned out a crop of 21,000 boxThe machinery of the "Habana," on the contrary, is rather indifferent, and not to be compared with that of the "San Martin" or "El Flor de Cuba," in the same neighborhood; and yet all agree that no sugar-planter of that country has surpassed "La Habana." Their loaves are of snowy whiteness, and bear favorable comparison with those of the refiner. superiority is generally ascribed to better land and better cane; but it is very singular that the adjacent estates, possessing soil of the same character and the same kind of cane-la caña blanca, commonly known as the Tahiti canedo not produce equally fine sugar.

es.

The

While capital has been lavished on costly machinery, and vast improvements have been made in the manufacture of sugar, the general principles of defecating with lime, filtering with bone charcoal, and concentrating under a vacuum have remained unchanged, although it has long been felt that some chemical substitutes for the present expensive process would be very desirable, and some of the best chemists of Cuba and the United States have long studied this problem.

In the first pan the guarapo, after coming from the smaller filters, receives its first boiling, the pipes being heated for the purpose with the exhaust steam of the engine which works the grinding-mill. A dense steam arises, which passes into the heating-pipes in the next pan, and gives heat to concentrate the sirup to 28° Baumé. The sirup then passes into caldrons furnished with the steam coil for further defecation, and thence into the large filters, passing from them into the strike-pan, as in the Derosne apparatus. The strike-pan, or third pan, is supplied with fresh steam from the boilers. The condensation of the waste steam, both for the purpose of maintaining the vacuum and for keeping a constant current of fresh steam in the heating apparatus, is maintained by a small vacuum-engine, a steam injection-column, and a fan for cooling the condensed water. Water being very scarce in many places, it is necessary that the same supply should be used over and over again, and the devices for economizing wa-olution, and Señor Alvaro Reynoso, of Havana, ter are very ingenious. One of the finest mills in Cuba using the Rillieux train is that of Don Diago at Perico, called the Yngenio Tinguaro. It has a train made by Merrick and Sons, of Philadelphia, from which a "strike" of 260 panes, or about 2500 pounds of green sugar, can be made at once, and the three vacuum-pans,

Any process which would do away with the use of animal carbon and prevent the formation of molasses in boiling would work a great rev

announces that he has discovered such a process. It as yet remains a secret, and but for the high reputation and chemical experience of the gentleman claiming to have made the discovery its announcement would be received with incredulity. Señor Reynoso, however, is the director of the Institute for Experimental Chemistry in