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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    6. Phosnhite of potash is very deliquescent, uncrystallizable, but insoluble in alcohol. Those of soda and ammonia are also very soluble. The former crystallizes in rhomboids approaching to cubes. All the rest are sparingly soluble, but can be obtained in crystals only bv spontaneous evaporation, for they are decomposed by heat, and salts with excess of base are precipitated, which are absolutely insoluble. There exist, therefore, neutral phosphites, sub-phosphites, and super-phosphites, the exact composition of which remains to be investigated.* SECTION V. Hypo-phosphorous or l'er-phospliorons Acid. When phosphuret of barytes> carefully prepared, is made to act on water, two distiuct compounds are generated, viz. phosphate of barytes, which, being insoluble, is readily separated by nitration; and a soluble salt of barytes, which passes through the filter. To the latter compound, sulphuric acid is to be added, in quantity just sufficient to separate the barytes. The acid solution which re- mains, when concentrated by evaporation, yields a viscous fluid, strongly acid and uncrystallizable. By a still stronger heat, this substance is decomposed; phosphuretted hydrogen is deve- loped; a little phosphorus is sublimed; and phosphoric acid remains in the retort.t The compounds of this new acid, with alkaline and earthy bases, are remarkable for their extreme solubility. Those of barytes and strontites crystallize with great difficulty. The hypo-phosphites of potash, soda, and ammonia, are soluble, in all proportions, in highly rectified alcohol. That of potash is even more deliquescent ti>aii muriate of lime. They absorb oxygen slowly from the air, and when heated in a retort give the same products as the acid itself. In order to ascertain the proportions of the elements of this acid, Dulong, its discoverer, converted a known quantity of it into phos- phoric acid by means of chlorine, whence he infers it to consist of Phosphorus .... 72.75. .... 100 Oxygen 27.25 .... 37.44 100. These results are calculated on the supposition that hypo-phos- phorous or per-phosphorous acid is a binary compound of oxygen and phosphorus; but it is doubtful whether it may not be a triple compound of oxygen, phosphorus, and hydrogen, or a hydracid; in which case its proper appellation would be hydro-phosphorous acid. * Dulong, 48 Phil. Mag. 272. t Dulong, 48 Phil. Mag. 271.