was led to suspect this fact by the taste of the beet, and by the cristalline appearance which it presented when examined under a microscope. His first experiments, which are detailed in a memoir read before the Academy of Sciences at Berlin, in 1747, although rude and unskilful, yet enabled him to announce the discovery. His process was simple-over a certain quantity of the root dried and powdered, he poured twice the quantity of highly rectified spirits, and exposed the mixture to a slow heat over a sand bath, until it began to boil, he then filtered it into a glass vessel which he closed, and at the end of some weeks, discerned cristals, which presented all the physical and chemical characters of sugar from the cane. The alcohol which remained, contained sugar in solution, and a resinous substance.

Other roots were in succession tried; several yielded sugar, but none in proportions equal to that of the beet. When the existence of sugar in these roots was once established, many plans were tried to extract it in a manner easy and economical. It is needless to trace his steps. He was aware of the possible importance of his discovery, and recommended it to farmers as opening a new branch of national industry. But the low price of sugar, and the imperfect state of chemical knowledge, which rendered his best attempts comparatively expensive, discouraged all serious efforts, and his researches were almost forgotten when, nearly a half century afterwards, M. Achard, also of Berlin, resumed the subject, and improved the ancient processes so much as to create a strong presumption that sugar on a large scale, might be extracted profitably from this vegetable.

The first experiments, however, were not successful. Inattention to many collateral circumstances which required consideration, ruined several establishments, and made the opinion common, as perhaps, is now the case with us in regard to the Sugar Cane, that the extraction of sugar from the beet root, though true in theory, could not advantageously be reduced to practice. Yet the moment was favourable, and the Emperor Napoleon, besides granting premiums for the most successful experiments and sending instructions into every department of his empire, established schools of chemistry in Paris, Wachenheim, Douai, Strasburg, Castelnaudary, for the express purpose of improving the fabrication of this sugar; and four imperial establishments were created, sufficient to manufacture from the crop of 1812, two millions of kilogrammes of raw or muscovado sugar.

These enterprises were just beginning to prosper when the political events of the year 1814 appeared to overwhelm them.

They were not only exposed to the free competition of a reviving and no longer interrupted commerce, but became a subject of ridicule to all who were desirous of throwing into discredit the institutions of Napoleon. Some, however, who had devoted much attention to this manufacture, particularly the distinguished chemist Chaptal, Messrs. Mathieu de Dombasle, and CrespelDelisse of Arras, continued their labours, and have ultimately demonstrated, that the sugar extracted from the beet can, under favourable circumstances, compete with that produced by the

cane.

The process recommended by M. Achard is nearly as follows. The juice, as expressed from the beets is received in large vats. Sulphuric acid is added in the proportion of two and a half grammes of acid to each litre of juice. The juice thus acidified is suffered to remain for twenty-four hours. At this time, the surface of the liquid ought to be clear and limpid, but the lower part will be still turbid by the deposition of albuminous substances, coagulated by the acid and by other impurities. The whole is then thrown into a boiler, over the bottom of which has been uniformly spread a thin layer of chalk. The boiler ought not to be filled more than to two thirds of its height to leave room for the froth which is formed during the effervescence caused by the decomposition of the chalk. The juice is stirred that the combination of the acid and alkali should be more complete. The sulphate of lime, formed by this combination, being nearly insoluble, is precipitated, and forms much of the sediment which falls to the bottom.

The proportion of chalk used, according to M. Achard, is much greater than is necessary to saturate the sulphuric acid mingled with the juice, but he considers it better to use this substance freely, than not to saturate the acid. The chalk used in this operation ought to be very pure, for sometimes it is combined with ingredients that might injure the clarification of the juice.

M. Achard at first proposed that a small quantity of quicklime should be added after the effervescence to neutralize any portion of the carbonic acid gas which might remain in the liquid. It has been found, however, that this gas will always be driven off by the heat to which the juice must be exposed.

When this first process is terminated, fire is kindled under the boiler, and when the liquid reaches the temperature of 30° R.99° F. skimmed milk is added in the proportion of ten to fourteen parts for every one thousand of juice. The mass is then stirred, and the boiler covered, when the thermometer rises to 79° R. 209° F., the fire is extinguished, and the fluid suffered to cool to

50° or 60° 62-75 F. The boiler is then uncovered, and a black crust which is found floating on the surface, carefully removed.

These preparatory measures of M. Achard have been modified by M. Crespel, of Arras. Besides some changes in the vats not important to us, the milk used by M. Achard has been replaced by bullock's blood, and the carbonate of lime by slacked lime. He has also ascertained that it is not necessary that the acid should remain some time in the juice before the application of alkalies. His process is the following: to 1800 litres of juice while cold, 2600 grammes of sulphuric acid diluted in three times their weight in water, are added; after having been sufficiently agitated, four kilogrammes of quick lime, mixed with water until it becomes fluid, are poured in, and the mixture stirred again. Fire is then applied. When the heat is raised to 70° Reaumur, animal charcoal which has been once before employed in clarifying sugar, is added, afterwards bullock's blood diluted with water; the whole is well mingled, and the fire is withdrawn to permit the liquid to settle, afterwards the clear juice is drawn off by a cock placed some inches above the bottom.

A second process is detailed, which resembles so much the usual practice of the West India planter, that it is called the " process of the colonies." This we shall not repeat. A third, which our authors represent as the one now generally adopted in the French manufactories, and recommended by M. Chaptal and Mathieu de Dombasle, we shall extract from the work before us.

"The alterations which lime, when employed in excess, produces in sugar, have caused persons to seek the means of protecting themselves from the injury occasioned by its presence in the juice after it is clarified. It has been advised to neutralize it by an acid, and sulphuric acid is preferred, because it is cheap, and because it forms with lime an almost insoluble salt.

"After having supplied the juice with lime as we have already mentioned, in the proportion of about five grammes to each litre, in the cauldron for defecation, the clear liquid is poured out into the boilers for evaporation. Into the liquid, which is then more or less alkaline, according to the quantity of lime which has been employed, sulphuric acid diluted with water is poured until the lime is very nearly neutralized, taking care, however, that the liquor preserves a little vestige of the alkali, an excess of the acid being more injurious than an excess of lime. The degree and point of saturation can easily be discovered by paper tinged blue with turnsole, which is changed to red by an excess of acid; paper dyed yellow by the curcuma, which alkalis turn to red, or by the syrup of violets which they change to green, will detect the excess of lime.

"Some manufacturers, and their method is, perhaps, to be preferred; add the sulphuric acid in the cauldron for defecation after the admixture of lime; by this means, the deposits occasioned both by the action of lime and by the sulphuric acid are united, the operation is simplified, and in the evaporating vessels nothing remains but to clarify and concentrate the liquid." p. 183.

We have given these various practices that it may be seen how the same principle may be modified and applied under different circumstances. It would seem from the result, as if both acids and alkalis may be beneficially applied. Each may correct in turn some quality in the juice that would obstruct the perfect cristallization of the sugar. So anxious are the manufacturers at the same time to prevent any waste, that the scum taken from these cauldrons is filtered, then placed in sacs and pressed, to force out all the juice that may adhere to it.

By this purification, the syrup freed from a part of the foreign substancs with which it was combined, has lost in its density as measured by the areometer, one or two degrees, it is then evaporated until it is reduced to one-fifth or one-sixth of its volume. As the water evaporates, light flakes of extraneous matter which were held in solution and injured the transparency of the liquid, separate from it and rise to the surface. To favour the formation of the scum, the heat is kept moderate, and sometimes a little blood or the whites of eggs are mingled with the liquid. When no more scum rises the fire is increased.

When the liquid marks 26° on the areometer when boiling, or 30° when cold, it is sufficiently concentrated. The contents of two evaporating boilers are poured into one, which are then clarified, that is to say, freed from any foreign matter which the syrup may still retain.

"The first thing to be done before the clarification commences, is to examine the liquid and ascertain if it contains an excess either of acid or of alkali. This, if it exists, must be corrected, until the syrup shall be found very slightly alkalescent. This verification being made, to every hundred litres is added five kilogrammes of animal charcoal; the liquid is made to boil, and is well agitated, the scum that forms on the surface is broken up, the sediment stirred, and this is continued until the charcoal is thoroughly diffused and suspended. The syrup has then the appearance of a black and turbid mass. The ebullition is continued for some minutes. In the meantime, for each hundred litres of syrup, either one litre of blood, or two litres of milk, or five eggs are diluted with water, and this mixture is poured into the boiler, taking care to stir the whole violently, until the boiling which had been arrested by the addition of this cold liquid, commences anew This is again suffered to continue for a short time. It is known that the quantity of blood or eggs which VOL. III.—No. 6.

45

has been added is sufficient, if the syrup, when held up against the light, is perfectly transparent, while the charcoal floats in it in grains or clots. If the syrup does not exhibit this appearance, more blood or eggs must be added. When perfectly clarified, it must be filtered through woollen cloth, and kept as warm as possible that the filtration may be more rapid.

"The deposit which remains on the filtre, and which is composed of animal charcoal, of the albuminous substances which have been employed, and which have been coagulated by the effect of heat, and of matters separated from the syrup, is impregnated so strongly with sugar, that it is found advantageous to separate it, by washing this residuum. The animal charcoal which has once served to clarify syrup, can be made useful again by employing it in the first boiler, (as we have a!ready mentioned) to aid in freeing the juice from its fecula; from this boiler it is thrown away with the scum." p. 187, et seq.

Several modes of applying the animal charcoal to the syrup are mentioned, but none of the variations are important. M. Chaptal throws this substance gradually into his boilers, and finds it sufcient to clarify the liquid without blood or eggs. The syrup when clarified and cooled, marks 30° on the areometer. This density is not sufficient to cause the sugar to cristallize, nothing, or scarcely anything, however, at this stage of the process remains mingled with the saccharine particles but water, and this, in other vessels, is soon made to evaporate. In this operation, if any scum appears, it is carefully removed, sometimes if it should seem necessary, the white of an egg is added, the heat is raised to 89°-91° of Reaumur, (about 250 Fahrenheit), and the evaporation continued until about 40 per cent. of the fluid which entered these last vessels has been dissipated. Care is necessary after the heat is increased to 85° to prevent, by moderating the fire, the syrup from burning. The syrup is now emptied into coolers and permitted to cristallize.

To promote the cristallization, or as it is called, the formation of the grain, when poor syrup has been obtained, a thin layer of brown sugar is sometimes placed on the bottom of the cooler before the concentrated syrup is poured in. It is well known that a solid body placed in a solution, serves as a nucleus, around which the molecules of a cristallizable substance will readily collect.

The draining presents nothing which it is necessary to notice. But the molasses which drains from the sugar is concentrated and clarified anew to extract from it all the cristallizable sugar which it has retained, and which amounts sometimes to onesixth part of the whole quantity. The molasses which is obobtained after a second cristallization, is only fit for the distillery.