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dissolving the metal in nitromuriatic acid, and diluting the solution with a large quantity of water.
Tellurium combines with hydrogen, and with it forms a gaseous substance, called telluretted hy, drogen.
This metal is scarce, and its combinations yet little known.
This metal is rare. It was discovered in a mineral, found in Cornwall, called menachanite. It was afterwards procured from another mineral, títanite, and some others. The metal when pure is brittle, very infusible, of a brass õř. copper cólour, easily tarnishes in the air, and oxidizes by heat. There appear to be thrée oxides of titanium, the blue, the red, and the white.
The ores of titanium are either pure crystallized oxidé, or the oxide united to iron, or to silex.
This substance, little known in the metallie state, is important on account of the fine pigments it affords. It is capable of being acidified, and the chromic acid forms salts. The beautiful mineral called red-lead of Siberia, is a chromate of lead, This is now artificially prepared, and is a very va. luable and beautiful yellow pigment. The chromic acid also unites to iron, the chromate of iron being found native; and it is from this that the chromic acid is procured and united to lead, to form the chromate of lead. Chromate of iron is, therefore, much sought after, and is found in greatest abundance in America, from whence our colour-makers chiefly procure it.
The pure metal is of a tin colour; it is very brittle, and is said to be magnetic. It is very infusible, and is not altered by the air, though when heated it is converted to an oxide.
Besides its acid, it seems to combine with oxygen in two other proportions, forming the green and brown oxides.
This metal was discovered by Werner, in a mineral called pechblende, a blackish mineral resembling pitch.
Metallic uranium is brittle, and very infusible. It is of a grey colour. It is obtained with extreme difficulty, and little known.
Its oxide is greenish-yellow, and is found native, resembling green mica, and also in an earthy state.
This metal was discovered by Mr. Hatchet in analyzing an ore from North America. It has since been found in the minerals called tantalite and yttro-tantalite. The metal has been procured by Berzelius. It is of an iron colour, hard and brittle, and passes into an oxide at a red heat.
Its oxide is white. Its combinations are little known; but it is one of the acidifiable metals.
This metal was lately discovered by Berzelius, in a mineral which has been called cerite. The characters of the metal are imperfectly known, as
it has been scarcely seen. The oxide of cerium (cerite) is found native. There appear to be two oxides, the white and the red.
Selenium is a metal lately discovered by Berzelius in the sulphur of Fahhun, in Sweden. Its metallic lustre is considerable, and colour grey. It easily fuses and volatilizes before the blow-pipe, with a smell like horse-raddish. It alloys with the metals. It dissolves in nitric acid, and forms with it a substance which is considered as a new acid, selenic acid, which unites with alkalies, forming seleniates.
Animals and vegetables differ essentially from minerals, in the two first possessing life and various organs fit for maintaining it, which is called organic structure. Through these organs, various juices and fluids circulate internally, and thus occasion the growth of the animal or plant. In mineral bodies this is not the case; they increase in size only by successive portions of matter adhering to the outside, nor is there any internal motion.
The principal ingredients of all vegetables are, oxygen, hydrogen, and carbon : sometimes they contain also a little nitrogen, and other elementary substances; and although these elements are few, yet, by many varieties in their proportions and modes of combinations, a great quantity of proximate constituents are produced.
Vegetable substances may be decomposed, or separated into their elementary principles by various means; by heats, by acids, and by fermentation : some of these processes occasion not only decomposition, but also new combinations of the elements that did not exist in the living bodies.
The principal substances of which all vegetables consist are,
Mucilage, or gum,
Mucilage, or gum. - Various parts of vegetables impart to water, particularly if boiled with them, a certain viscous consistency: the substance so dissolved is called mucilage. Some trees suffer their mucilage to transude, either spontaneously or by incisions made in them. When it has become concrete by drying in the air, it is called gum.
Gum is soluble in water, but not in oils or al. kohol, the latter of which precipitates it from its solution in water. It is insipid; it does not undergo any change by exposure to the air when dry. The gums of different trees differ considerably in their properties.
Gum arabic may be considered as a very pure gum, Cherry-tree gum and gum tragacanth do not dissolve in cold water ; but dissolve in boiling water, and, on cooling, assume the state of a jelly.
Gum consists of carbon, oxygen, and hydrogen.
Sugar.-The sugar in common use is extracted from a cane that grows only in warm climates, called the sugar-cane; but it may also be procured from all sweet vegetables. The American maple-tree affords a great deal of sugar, and this useful substance has been made from the beet-root, carrots, &c. All
sugars consist of carbon, oxygen, and hydrogen; but it appears that sugar from the cane contains more carbon than other sugars. That obtained from some vegetables will not crystallize. Sugar is first prepared in the countries where it is grown, by boiling the juice and evaporating ; one part of the juice crystallizes, and forms the raw or muscovado
sugar; the other part, the molasses or treacle, will not crystallize. The raw sugar when brought to this country is re-dissolved and crystallized again, which is called refining, by which the loaf-sugar is made. To whiten it completely, clay is put upon the tops of the conical pots in which the sugar has granulated, which allows water to percolate through, and thus drain off the last remains of the molasses. This is called claying the sugars.
Fecula, or starch. This substance is contained in many seeds and roots. It is separated by bruising the vegetables containing it in water, and stirring them together. The fecula separates in the water, making it appear turbid. The white fluid is poured off and suffered to settle ; the starch subsides to the bottom. Starch is made mostly from wheat; it is also made form potatoes. Starch is a white substance, insoluble in cold water, but soluble in warm. Its solution is gelatinous, and when solid it resembles gum : this, when dry, is a com