A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 1).

  • Andrew Ure
Date:
1821
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Licence: Public Domain Mark

Credit: A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 1). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    Boiling water scarcely dissolves one fif- tieth part, and cold water much less. When this solution is distilled in close vessels, part of the acid rises with the wa- ter, and crystallizes in the receiver. It is more soluble in alcohol, and alcohol con- taining-it burns with a green flame, as does the borate of ammonia, to be about 2.7 or 2.8; oxygen being 1 0; and it probably consists of 2.0 of oxygen -f- 0.8 of boron. But by M. M. Gay-Lussac and Theuard, the proportions would be 2 of boron to 1 of oxygen.* The boracic acid has a more powerful paper dipped in a solution of boracic acid, attraction for lime, than for any other of Neither oxygen gas, northe simple com- the bases, though it does not readily form bustibles, nor the common metals, pro- borate of lime by adding a. solution of it to duce any change upon boracic acid, as far lime-water, or decomposing by lime-water as is at present known. If mixed with the soluble alkaline borates. In either finely powdered charcoal, it is neverthe- less capable of vitrification; and with soot it melts into a black bitumen-like mass, which however is soluble in water, and cannot easily be burned to ashes, but sub- limes in part. With the assistance of a case an insipid white powder, nearly inso- luble, which is the borate of lime, is how- ever precipitated. The borate of barytes is likewise an insoluble, tasteless, white powder. Bergmann has observed, that magnesia. distilling heat it dissolves in oils, especial- thrown by little and little into a solution of ly mineral oils; and with these it yields boracic acid, dissolved slowly, and the li fluid and solid products, which impart a green colour to spirit of wine. When nibbed with phosphorus it does not pre- vent its inflammation, but an earthy yellow matter is left behind. It is hardly capa- ble of oxidizing or dissolving any of the me- tals except iron and zinc, and perhaps copper; but it combines with most of the metallic oxides, as it does with the alka- lis, and probably with all the earths, though the greater part of its combinations have hitherto been little examined. It is of great use in analyzing stones that con- tain a fixed alkali. * Crystallized boracic acid is a compound of 57 parts of acid and 43 of water. The honour of discovering the radical of bora- cic acid, is divided between Sir II. Davy and M. M. Gay-Lussac and Thenard. The quor on evaporation afforded granulated crystals without any regular form : that these crystals were fusible in the fire with- out being decomposed ; but that alcohol was sufficient to separate the boracic acid from the magnesia. If however some of the soluble magnesian salts be decom- posed by alkaline borates in a state of so- lution, an insipid and insoluble borate of magnesia is thrown down. It is probable, therefore, that Bergmann's salt was a bo- rate of magnesia dissolved in an excess of boracic acid ; which acid being taken up by the alcohol, the true borate of magne- sia was precipitated in a white powder, and mistaken by him for magnesia. One of the best known combinations of this acid is the native magnesio calcareous borate of Kalkberg, near Lunenburg: the first, on applying his powerful voltaic bat- ivurfelstein of the Germans, cubic quartz of tery to it, obtained a chocolate-coloured various mineralogists, and boracite of Kir- body in small quantity ; but the two latter wan. It is of a grayish white colour, chemists, by acting on it with potassium sometimes passing into the greenish white, in equal quantities, at a low red heat, or purplish. Its figure is that of a cube, formed boron and subborate of potash, incomplete on its twelve edges, and at For a small experiment a glass tube will four of its solid angles; the complete and serve, but on a greater scale a copper incomplete angles being diametrically op- tube is to be preferred. The potassium and boracic acid, perfectly dry, should be intimately mixed before exposing them to heat. On withdrawing the tube from the fire, allowing it to cool, and removing the cork which loosely closed its mouth, wc then pour successive portions of water into it, till we detach or dissolve the whole posite to each other. The surfaces gene- rally appear corroded. It strikes fire with steel, and scratches glass. Its specific gravity is 2.566, as determined by M. Westrumb, who found it to be composed of boracic acid 0.68, magnesia 0.1305, lime 0.11; with alumina 0.01, silex 0.02, and oxide of iron 0.0075, all of which he matter. The water ought to be heated considers as casual. Its most remarkable each time. The whole collected liquids property, discovered by Hauy, is, that are allowed to settle ; when, after wash- like the tourmalin it becomes electric by in°-the precipitate till the liquid ceases to heat, though little so by friction; and it affect sirup of violets, we dry the boron has four electric poles, the perfect angles in a capsule, and then put it 'into a phial always exhibiting negative electricity, and out of contact of air. Boron is solid, taste- the truncated angles positive, less, inodorous, and of a greenish brown Since the component parts ot this na- colour. Its specific gravity is somewhat five salt have been known, attempts have greater than water. The prime eqniva- been made to imitate it by art; but no Pent of boracic acid has been inferred from cliemist has been able, by mixing Hme, Vox, i. r *■]