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366 Celestial Phenomena from Oct. 1. 1832 to Jan. 1. 1833.

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Times of the Planets passing the Meridian, and their Declinations.

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SCIENTIFIC INTELLIGENCE.

METEOROLOGY.

1. Unctuous Dew.-In the neighbourhood of Rotterdam, it has been recently observed, that the morning dews, instead of being pure and limpid, are of an unctuous consistency.

CHEMISTRY.

2. The New Vacuum Sugar.-The grains of this beautiful sugar are true and well-formed crystals. They do not melt so readily as common sugar,- -a circumstance that induces some inaccurate observers to imagine that this sugar is not so sweet as common muscovada. The taste is just that of fine candy. The advantage is, that this sugar is far less hygrometric than common raw sugar, and suffers less from a moist atmosphere. The apparatus used in its preparation is a modification of the late Mr Howard's apparatus for boiling sugar in vacuo; with strainers of copper-plates pierced with minute holes, or several folds of wire-gauze for clarifying the syrup. The process is, immediately on crushing the canes, to heat, lime, and scum the juice, which, while warm, is forced through the strainer, from which it runs into the boilers. These are provided with airtight covers, the tops of which are connected by tubes with a large air-pump, wrought by a steam engine. The steam, as generated, is thus drawn off, and the boiling is carried on at a temperature far below the boiling point of sugar. When sufficiently concentrated, the syrup is crystallized, and, when consolidated, it is carried to the curing-house, the temperature of which is kept up by steam-pipes running into it. This process saves much sugar, for the heating being low, little or no molasses are formed, and a large quantity of sugar is obtained, which, in the old process, is converted into molasses. This apparatus was adopted by sugar-growers in Demerara, on the suggestion of a distinguished philosopher in Liverpool. The experiment has succeeded admirably; and the sugar bears a premium in the Liverpool market, especially when required for coffee.

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3. On the Grease of Wines.-White wine is subject to an alteration which is designated in Switzerland, and other countries, by the terms greasy and ropy, (tourner au gras, graisser, filer), a change which takes place after the vinous fermentation has apparently ceased, and the wine has been bottled or closely confined in casks. The wines of Champagne, of Switzerland, and most thin and light wines, are very subject to it, especially when the vintage has been wet. The cause of this malady resides in a mucilaginous principle which is developed in light wines: it pervades the whole mass, and puts on a reticulated appearance; a similar change is observable in beer, and in syrups made of sugar of an inferior quality. Various methods have been pursued for remedying this defect. Common salt is added to the wine, a practice which was adopted, it is said, by the Romans, in consequence of an accidental discovery of an amateur in wines. Having opened an amphora of wine, and being struck with its excellence, he demanded of his slave what he had put in it. The latter, mistaking his master's meaning, fell on his knees and confessed he had drank a little wine and filled up the vessel with sea-water. After two or three months, it is impossible for the most delicate palate to distinguish the taste of salt, and it is admitted that such an addition improves the taste of the wine, but that it prevents the grease is a point much more doubtful. Another remedy is the addition of brandy or alcohol. But the more efficacious means of all is a frequent racking off, or decantation. Wine must never be allowed to whiten, that is, to admit the rising of a milky substance, which destroys its transparency. When this disease has been contracted, it may often be removed by clarification with fish glue; but this remedy has two inconveniences, it does not always succeed, and when it does, it diminishes the strength of the wine. This deterioration arises either from the glue, or perhaps from the disease itself, which has occasioned the operation. Another method of clarifying wines and removing the grease, consists in filtering them through shavings of hazel. For small quantities this method is very good. When the sale of wine is not pressing, and care is taken to keep the vases which contain them full, and they are allowed to undergo a slow and insensible fermentation, and are exposed to the change of temperature which the season brings round, this disease sponVOL. XIII. NO. XXVI.-OCTOBER 1832.

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taneously disappears. It is rare that greased wines thus treated are not cured in passing through the cold of one winter. The attention of chemists has been much engaged with the nature of this quality in wine. M. François of Chalons-surMarne, ascribes it to a substance which is found also in the gluten of wheat flour, and which M. Taddei, an Italian chemist, discovered and named Gliadine. It is the portion which is soluble in alcohol, the insoluble portion he called Zimome. If an alcoholic solution of gliadine be added to clear wine, it be comes milky, and assumes, according to M. François, the aspect of greased wines. Berzelius, however, does not believe in the gliadine of Taddei. He considers it to be gelatine, and the zimome to be albumen, both of which have been long known to exist in the gluten. The same chemist has proved that vegetable and animal gelatine are identical in the properties of uniting with tannin and forming an insoluble precipitate. However this may be, M. François has been induced to regard tannin as a remedy for the grease of wine. of wine. He accordingly makes an observation which seems to have escaped all those who had previously examined the subject, that red wines are never subject to the grease. Now, the difference between red and white wine is, that the red always ferments in presence of the husk and seeds of the grape, substances which contain tannin in abundance, while white wine remains in contact with the husk but a very short time. It is also a fact, that light wines made of grapes deprived of their seeds are more subject to this disease than others. Hence it is probable, that the presence of tannin may, by precipitating the gelatine, prevent the phenomena of the grease. The following are Mr François's directions: By adding tannin to wine a month or six weeks prior to bottling, it may be preserved from the grease; and this substance being one of those which exist in wine, it may be added without fear, for it communicates no unnatural odour or taste. Twenty grains of tannin to a bottle of wine, or three and a half ounces to a hundred bottles previously well decanted from all sediment, is the proper dose, although in frequent cases this dose must be repeated. If any sediment remain in the wine, a much larger dose of tannin becomes necessary. M. François affirms that this malady in wine, when once destroyed, never returns. As the tannin of chemists is an expensive article, obtained from the

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