Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin.

  • Dobbin Leonard.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    157/898 (page 135)
    Note.—Barium, strontium, and calcium are also precipi- tated by alkali-metal phosphates and arsenates. The other precipitants of magnesium are also precipitants of barium, strontium, and calcium. Hence the analyst always removes any barium, strontium, or calcium by an alkali-metal carbon- ate, as above indicated; sodium phosphate (or ammonium arsenate or phosphate) then becomes a very delicate test for the presence of magnesium. In speaking of magnesium tests, the absence of barium, strontium, and calcium salts is to be understood. DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF ONE OF THE METALS, BARIUM, STRONTIUM, CALCIUM, MAGNESIUM. To a portion of the solution add ammonium chloride, ammonia (until the liquid, after shaking, smells of ammonia), and ammonium carbonate. A white precipitate is produced. Acidulate another portion of the original solution with acetic acid, and add potassium chromate.* An immediate No immediate precipitate is yellow precipi- formed. To another portion tate indicates of the original solution add cal- jja cium sulphate. A white pre- j No precipitate cipitate,formed even on stand- on standing for ing or on boil- some time, or ing, indicates on boiling, in- £a dieates Sr Confirm Ba, Sr, or Ca by flame-test. Potassium bichromate must not be used in these operations, or a portion of the barium will remain in the liquid and be precipitated along with, or in the place of, the calcium carbonate {sm p. 115). The potassium chromate used must not contain carbonate, or calcium will be precipitated along with, or in the place of, barium. (The absence of carbonate may be proved by the non-occurrence of effervescence on the addition of hydrochloric acid to a little of the solution of the chromate, previously made hot in a test-tube.) No precipitate is produced. To the same por- tion add ammo- nium phosphate. A white crys- talline precipi- tate produced either at once, or on standing for some time, indicates Mg