densed water, and leading through the top of the iron cylinder is a continuation of the waste-water pipe, which descends to within two inches of the bottom of the bucket. By the steam condensed running into the cylinder on the outside of the bucket, it is floated up until its bottom, touching the end of the waste-water pipe, closes the opening, but the quantity of water increasing, overflows the bucket, which, sinking proportionately, opens the pipe as needed, and allows the water to escape to the reservoir. An apparatus so simple and so little liable to derangement, besides that it requires no care, should be better known and more used. Another advantage in the improved pans is, the pipes are so connected that by turning off one coupling, the whole may be raised as a door on a hinge, to facilitate the cleaning.

In the use of steam, there are some phenomena worthy of especial notice. It was observed by Dalton, that to condense one pound of steam, five and a half pounds of water were required, and this water was raised by the steam, from a temperature of 60° up to 212o. It was also noticed that the time required to evaporate a given quantity of water by a certain continued supply of heat, was five and a half times as long as it took to raise the water from 60° to 2120. That the latent heat of steam increases with its rarity at low temperatures, and diminishes with its increasing density at high temperatures. From which facts we derive the points, that the economy in the use of steam for purposes of evaporation, lies in maintaining a current of vapor of low temperature, without permitting the part condensed to be lost. For, as it takes but one part of fuel to generate vapor from boiling water, it takes five and a half parts to raise the water to boiling. High steam does not contain proportionate increase of sensible heat. As resistance to formation of steam exists in fluids more strongly from the pressure of the atmosphere than from the attraction of their atoms, on the removal of this pressure entirely, the fluid will boil, in vacuo, at about 140° less than in the open air. This fact exhibits the economy of the vacuum-pan so far in the process as to the commencement of ebullition, but beyond that point, the steam produced being more expanded and rare, has a greater latent heat; wherefore, unless the vapor taken off can be used as a fund of heat, there is no economy of fuel in the use of a vacuum, more than in the open pan.-Arnott.

It was only when Watt had discovered, by the experiments of Dr. Black, how much heat was lost when steam was lost, that be contrived the separate condenser for his steam-engine, by which was at once saved three-fourths of the fuel formerly used.-(Renwick.) This has been partially applied in the "heaters" of the high-pressure engines now so common throughout the country, and is an

apt illustration of the economy of using the waste steam from the plantation engine for clarification; that the juice, being then near the evaporating point, requires but a small accession of heat to bring it to the boiling point. Further, the escape steam, if not so One or two used, would be an entire loss. pounds of detention in the outlet from the clarifiers, will equalize its pressure throughout, and secure an equable application of heat, while it will not materially impede the engine by back pressure. The great advantage that steam possesses as a medium of heat, is, that it is so readily applied and governed, and that it very rarely attains the power of carbonization, so much the objecThe economy of its tion to the naked fire. production is doubtful, but of maintaining it as a continuous rotary source of heat, there remains not the least doubt, which the foregoing facts will not entirely remove. The facility with which it parts with its caloric, and the readiness with which the caloric can be applied, are illustrated by the fact, that it requires ten square feet of boiler fire-surface to supply four square feet of steam-pipe surface in an open pan. The estimate of some experienced engineers is even a greater disproportion, such as ten to three, and it is always desirable to have an abundant supply, as the rapidity with which the evaporation can be performed is the great desideratum in the use of such apparatus.

The very many methods invented to supersede the inconveniences resulting from cooking sugar over the naked fire, exposing it to be burnt, and increasing the quantity of molasses formed, to say nothing of the risk of fire to the buildings in which the operations are carried on, are curious, if not instructive, in the history of inventions, and a brief review of them may be interesting before we look into the apparatus in use at the present day; for it has been by successive steps that all improvements have been made, and from the position the manufacturer now occupies, his retrospective view will disclose to him the obstacles which others have encountered, and their expediences to overcome these will cease to be undervalued by him, as well as in his own manufacturing, to teach the true operations of physical laws.

From the application of the oil bath before spoken of, we see the oil applied through a spiral tube, as a medium of heat to syrups, but this also was entirely abandoned for the use of steam. The capacity of oil for heat was proved to be far greater than that of the syrup, and the contrivance wasteful of fuel. M. Milles Berry was the first to introduce the use of short steam-pipes, and his invention is well known as the French steam-pan. Increase of steam surface in double bottom kettles. the upper one being deeply corru gated, had not proved so effective in result as was anticipated, and this parallel structure of

pipes similar to a gridiron was introduced as bearing some resemblance, and having double the amount of steam surface. But here, more than in almost any other structure of pipes, the expansion and contraction of the metal being hot or cold, rendered the possibility of keeping the innumerable joints tight, almost out of the question. In this pan, the condensed water escapes by interior tubes, which doubly increased the difficulty. Knight, of Liverpool, introduced the plan of admitting hot air through a coil of pipe pierced with numerous small holes, into the boiling syrup, to carry off the vapor, while Vidder modified this invention by passing the hot air over the surface only, for the same purpose; and at a later day, to facilitate the formation of vapor in syrup, Milles Berry introduced several drums moving within each other, in the pan. But all of these contrivances had the same evil, that of churning the syrups and facilitating their oxygenation, producing color and uncrystallizable sugar. When the superior advantages of the vacuum-pan first became known, not only for the purpose of sugarmaking or refining, but equally for the superior quality of the extracts made by it, numerous were the plans resorted to for producing this required vacuum with the greatest economy and facility. The increase in volume of a liquid converted into vapor, being nearly seventeen hundred times, the large air-pumps and rapid strokes required before condensation of the vapor was thought of, led to extended machinery and increased cost of labor. The invention of the condensing cistern is therefore equally valuable as that of the vacuum-pan of Howard. He, too, like Watt. was indebted for the hints derived from the experiments of co-laborers, for his fame and success. Before this was applied as it now exists, we find that vapor was taken off through long coils of pipe placed in running cold water, just as stills are now constructed, and the pump producing the vacuum worked both vapor and water. This application of condensation was the source of another that in sugar-making is even now considered an improvement, from its economy of heat. MM. Chaponais, d'Abonille, and Cellier Blumenthal, each substituted cane-juice for water, in their condensers; their apparatus, more recently improved by Dumont, Degrand, and lastly by Derosne, has given us the great condenser of the Derosne and Cail apparatus, which is a succession of parallel pipes of large diameter, placed one above the other, to the number of twenty or thirty, over which the juice is made to fall in drops from one pipe to another, and is thereby considerably evaporated, and proportionably increased in value. But these vacuums all involved the use of an air-pump, which requires a large amount of motive power, and we find this led to the invention of Roth, a reservoir for steam (at a little distance from the vacuum pan),

into which was poured, through an extensive strainer, a large amount of cold water, which had for effect, after the expulsion of the air, and supply of its place by vapor, to condense this vapor as rapidly as formed, and thereby maintain a partial vacuum. Davis applied revolving floats, like those of a rotary churn, for the more rapid production of steam in the pan; and another appliance was a drawingpan to take off the vapor. But the perfection of the condensing cistern, as it stands in connection with the air-pump of the present day, has superseded all other contrivances. Now, there is required to be nearly water enough to condense all the vapor, and thereby lessen the amount of work for the pump, at the same time facilitate it, and perfect its operations. Too often, however, it is complained of as an intricate piece of machinery, and liable to disorder; whereas, if properly made and attentively worked, there is as little liability to disappointment as from any other pump. The use of water in large quantities being therefore indispensably connected with a vacuum-pan, limits its application to such localities as offer sufficient supply. To overcome this difficulty, and to make entirely available the whole amount of vapor discharged from a vacuum-pan, and thereby se cure even an extraordinary economy of fuel, has been left for the invention of M. Rillieux, and he has perfected the combination of the apparatus in a mauner not only of admirable adaptation, but good taste in structure, and such as will commend itself to any intelligent person who will devote some little time to become familiar with its operation. The method of operation is as follows:

The juice being clarified by the escape steam from the engine, is once filtered through animal coal, and then passed into the first vacuum-pan, which is also supplied by escape steam, as far as it will suffice, and if more is wanted, a direct communication is opened with the boilers; here the juice is evaporated ten or twelve degrees more, and then being at about 23° to 28" of the saccharometer, is again filtered through the coal, from which it comes, ready to be finished by boiling in the second and third vacuum-pans, which are supplied with steam from the first by acting as condensers to it, the syrup in them being made to boil in a higher vacuum, and of course at a lower temperature. As the vapor of the first pan is drawn into the tubes of the second, so the vapor made in the second pan is drawn through the pipes of the third, and at last condensed only when there is no farther use for it. As an economical process of evaporation, this method must supersede all others on large estates; and the eminent advantages it possesses in connection with the process of sugar-making, need no recommendation to the practical man. Without the use of the coal-filters, the juice is entirely excluded from the air, and, not being

to white; deeper yellow when ripe, and on rich ground. West India planters say it is the same sort as that which grows in the West India Islands; softer, more juicy than the Cadjoolee, but juice less rich, and produces sugar less strong; requires seven maunds of pooree juice to make as much goor or inspissated juice as is produced from six of the Cadjoolee. Much of this kind is brought to the Calcutta markets, and eaten

raw.

3. The white variety, which grows in swampy lands, is light-colored, and grows to a great height. Its juice is more watery, and yields a weaker sugar than the Cadjoolee. However, as much of Bengal consists of low grounds, and as the upland canes are liable to suffer from drought, it may be advisable to encourage the cultivation of it, should the sugar it produces be approved, though in a less degree than other sugars, in order to guard against the effects of dry seasons. Experience alone can determine how far the idea of encouraging this sort may answer.

Punsaree, Reonda, Mungoo, Newar, Kiwahee. Different sorts produced in the Benares district;-probably some of them may be of the sorts already described. The punsaree and reouda appear to be the most productive and the most esteemed.

Besides the foregoing, several kinds are now known to the Indian planter. One of them, the China sugar-cane, was considered by Dr. Roxburgh to be a distinct species, and distinguished by him as Saccharum Simensis. It was introduced here, in 1796, by Earl Cornwallis, as being superior to the native kinds. It is characterized by a hardness which effectually resists most of the country rude mills; but this hardness is importantly beneficial, inasmuch as that it effectually resists the attacks of the white ants, hogs, and jackals, which destroy annually a large portion of the common cane.

Dr. Buchanan found that four kinds were known in Mysore. Two of these are probably the purple and white generally known; but as this is not distinctly stated, I have retained the form in which he notices them. Restali, the native sugar of the Mysore, can only be planted in the last two weeks of March and first two of April. It completes its growth in twelve months, and does not survive for a second crop. Its cultivation has been superseded by the other.

Puttapulti-This was introduced from Arcot during the reign of Hyder Ally. It is the only one from which the natives can extract sugar; it also produces the best Bella or Jagory. It can be planted at the same season as the other, as well as at the end of July and beginning of August. It is fourteen months in completing its growth; but the stools produce a second crop, like the ratoons of the West Indies, which ripen in twelve months

Maracabo, Cuttaycabo.-These two are

very small, seldom exceeding half an inch in diameter; yet in some districts of Mysore, as about Colar, the last named is the variety usually cultivated; but this arises from its requiring less water than the larger varieties.

The best varieties are those introduced from the islands of Otaheite and Bourbon. Hindostan is indebted for their introduction to Captain Sleeman, who brought them hither from the Mauritius in 1827. He committed them to Dr. Wallich, under whose care, at the Botanic Garden, they have flourished, and been the source from whence the benefit has been generally diffused. Their superiority over those which have been usually cultivated by the natives has been completely established. The largest of the Hindostan canes, ripe and trimmed, ready for the mill, has never been found to exceed five pounds; but it is not uncommon for an Otaheite cane,* under similar circumstances, to weigh seven pounds. The extra weight arises proportionately from an increased secretion of superior sap. The sugar is more abundant, granulates more readily, and has less scum. Other superior qualities are, that the canes ripen earlier, and are less injured by the occurrence of protracted dry weather.

Of the history of the sugar-cane, a popular tradition obtains among the natives, that, in very ancient times, a vessel belonging to their country chanced, by accident, to leave one of her crew, under a desperate fit of sickness, at a desert island at a considerable distance in the Eastern seas, and that, returning by the same route, curiosity prompted them to inquire after the fate of their companion, when, to their utter astonishment, the man presented himself to their view, completely recovered from his sickness, and even in a state of more than common health. With anxiety, they inquired for the physic he had so successfully applied, and were conducted by him to the sugar-cane, on which, he acquainted them, he had solely subsisted from the time of their departure. Attracted by such powerful recommendation, every care and attention was bestowed, we may suppose, to convey such an invaluable acquisition to their own lands, where the soil and climate have, mutually, since contributed to its present prosperity.

The Ryots consider the sugar-cane, and also the betel-plant, in a sacred and superior light: they even place it among the number of their deutohs. The first fifteen days of Koar, (or September,) termed Peetereputch, are de

Many are of opinion, founded on their experience, that although the juice of this cane is larger in quantity, yet that it contains less sugar. There is some sense in the reason they assign, which is, that in the Mauritius and elsewhere, it has the full time of twelve or fourteen months allowed for its coming to maturity-whereas the agriculture of India, and especially in Bengal, only allows it eight or nine months, which, though ample to mature the smaller country canes, is not sufficient for the Otaheite.