The elements of experimental chemistry (Volume 2).

  • Henry, William, 1774-1836.
Date:
1819
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Licence: Public Domain Mark

Credit: The elements of experimental chemistry (Volume 2). 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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    5. In oxymuriatic acid gas, it takes fire at common temperatures, and boracic acid is regenerated with a portion of the black matter al- ready described. i 6. It is not soluble either in nitrogen or hydrogen gases. 7. It decomposed the nitric and sulphuric acids, and boracic acid was produced. 8. It combined with alkalis, and gave pale olive coloured com- pounds, from which dark precipitates were separated by muriatic acid. 9. It slowly combined with melted sulphur, which acquired an olive tint; but with phosphorus scarcely any union seemed to take place. Neither did it combine with mercury. These qualities are sufficient to show that the combustible sub- stance, obtained from boracic acid, and constituting its base, is dif- ferent from every other known species of matter. Sir H. Davy has, therefore, proposed for it the term boron. As to its nature, he is of opinion that it is probably a compound, and that one of its ingre- dients, which enters into alloy with potassium and with iron, is the true basis of the boracic acid. The olive coloured substance, whose properties have been already described, he b%lieves to consist of this basis, united with a little oxygen; that when further oxydized it forms the black matter; and that, in its full state of oxygenation, it constitutes boracic acid. The proportion of ingredients in the boracic acid has not been ac- curately determined. It is stated, merely as an approximation, that it consists of one part by weight of inflammable base united with two parts of oxygen. In the black substance, Sir II. Davy supposes that about three parts of the inflammable base are combined with only one of oxygen. Boracic acid combines witli alkalis and earths; but the only im- portant combination, which it forms, is with soda. This compound is found native in India, and is brought to this country, under the name oftincal, or brute borax, which, when purified, attbrds the borax of the shops. In the borate of soda, the alkaline ingredient is in ex- cess, and hence the salt converts vegetable blue colours to green. It is therefore, in strictness, a sub-borate. Sub-borate of soda crystallizes in prisms with six irregular sides. It effloresces in the air. It fuses when ignited; loses its water of crystallization; and leaves a glass, which is transparent when cold, and which is of great use in experiments with the blow-pipe. The salt dissolves in twelve parts of cold water, or in six of boiling water. It is susceptible of combination, by fusion, with silex and with alu- mine; and hence is employed in making artificial gems. According to the experiments of Gmelin, it consists of Boracic acid .... 35.6 . . . 100 Soda 17.8 ... 50 Water 46.6 100. The remaining borates, which have been analyzed by Gmelin, are described in the 9th volume of Dr. Thomson's Annals, p. 48.