Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

    59/272 (page 41)
    SPEcIAL PROPERTIES OF THE Basic Grovres. FIRST GROUP. POTASH. SODA. AMMONIA. (LITHIA.) 95. The members of this group are called alkalies. They are readily soluble in water in their pure (caustic) state. The solution restores the blue colour of reddened litmus paper, and imparts an intensely brown colour to turmeric paper ; the solution of their sulphides and carbonates acts in a similar manner upon vegetable colours. 96. Potash and soda are oxides of the metals potassium and sodium ; these metals are lighter than water, and decom- pose it at the ordinary temperature. Ammonia (NH.), being a gas of a very pungent odour, is readily distinguished from all the other bases; it dissolves freely in water, and may be again expelled on boiling the solution. Ammonia, when dissolved in an aqueous solution, unites with one atom of water, forming NH.,0, the oxide of an hypothetical com- pound metal, ammonium (NH,). 97. Potash cannot be detected in the presence of ammonia or any of its salts; because the same reagents which preci- pitate potash from its solutions form also, with ammonia, a corresponding class of insoluble substances (A 3 and B 3); ammonia must therefore be expelled from the substance under examination, before proceeding totest for potash and soda. The way for expelling the ammonia is described in paragraph 108: