Of the hygroscopic substances in common use, phosphoric anhydride, concentrated sulphuric acid, and dry potassium hydrate are almost equal in power; sodium hydrate and calcium chloride are not much behind.
Hardy in 1875 (Ber., 8, p. 1594), and is a crystalline, very hygroscopic solid.
Oxygen and hygroscopic water are much higher than in true coals.
By warming its aqueous solution with an excess of silver oxide it is converted into tetramethylammonium hydroxide, N(CH3)40H, which crystallizes in hygroscopic needles, and has a very alkaline reaction.
It is almost colourless and has a small coefficient of expansion; its hygroscopic properties, its viscous character, and its action on the skin, however, militate against its use.
Potassium phenolate, C 6 H 5 OK, crystallizes in fine needles, is very hygroscopic and oxidizes rapidly on exposure.
To facilitate the communication of the charge to the needle, the quartz fibre and its attachments are rendered conductive by a thin film of solution of hygroscopic salt such as calcium chloride.
A very striking and remarkable fact, which has much practical interest, is its highly hygroscopic nature.
Otherwise a desiccator must be employed; this is essentially a closed vessel in which a hygroscopic substance is placed together with the substance to be dried.
They are mostly soluble in water and somewhat hygroscopic in character.