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.
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.
The spores differ from those of ferns in their outer coat (exospore) being split up into four club-shaped hygroscopic threads (elaters) which are curled when moist, but become straightened when dry.
After fusion the mass solidifies to a transparent vitreous solid which dissolves readily in water to form boric acid (q.v.); it is exceedingly hygroscopic and even on standing in moist air becomes opaque through absorption of water and formation of boric acid.
It is very hygroscopic, dissolves readily in water, and rapidly undergoes oxidation on exposure to air.
The root is made to press its way into the darker cracks and crannies of the soil, so bringing its root-hairs into better contact with the particles round which the hygroscopic water hangs.
Potassium phenolate, C 6 H 5 OK, crystallizes in fine needles, is very hygroscopic and oxidizes rapidly on exposure.
The seeds are minute and innumerable; they contain a small rudimentary embryo surrounded by a thin loose membraneous coat, and are scattered by means of hygroscopic hairs on the inside of the valves which by their movements jerk out the seeds.
It does not evaporate or turn rancid, whilst its marked hygroscopic action ensures the moistness and softness of any surface that it covers.
The oxidizing agent in commonest use is copper oxide, which must be freshly ignited before use on account of its hygroscopic nature.
The tough but flexible coarse grey paper (German Fliesspapier), upon which on the Continent specimens are commonly fixed by gummed strips of the same, is less hygroscopic than ordinary cartridge paper, but has the disadvantage of affording harbourage in the inequalities of its surface to a minute insect, Atropos pulsatoria, which commits great havoc in damp specimens, and which, even if noticed, cannot be dislodged without difficulty.
They are loose, white, non-hygroscopic powders, soluble in water and salt solutions, and have an acid reaction; they give the colour reactions of albumins.
The chloride is very hygroscopic. By heating in hydrogen it yields the trichloride, UC1 3, and by direct combination with chlorine the pentachloride, UC1 5.
It is extremely hygroscopic and is 'used in synthetical organic chemistry as a condensing agent.
Titanium dichloride, TiC1 21 obtained by passing hydrogen over the trichloride at a dull red heat, is a very hygroscopic brown powder which inflames when exposed to air, and energetically decomposes water.
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.
It melts at 224° C. and is exceedingly hygroscopic. Water decomposes it with formation of tellurous acid and other products.
It forms colourless, very hygroscopic prisms, which attack glass, slowly at ordinary temperatures, more rapidly when heated (Ber., 1909, 4 2, p. 49 2).
As the amount of ash varies very considerably in different coals, and stands in no relation to the proportion of the other constituents, it is necessary in forming a chemical classification to compute the results of analysis after deduction of the ash and hygroscopic water.
Oxygen and hygroscopic water are much higher than in true coals.
Hardy in 1875 (Ber., 8, p. 1594), and is a crystalline, very hygroscopic solid.
Anhydrous calcium chloride, prepared by heating the hydrate to 200° (preferably in a current of hydrochloric acid gas, which prevents the formation of any oxychloride), is very hygroscopic, and is used as a desiccating agent.
They are mostly soluble in water and somewhat hygroscopic in character.
The dry salt is very hygroscopic; it deliquesces into an oily solution ("oleum tartari") in ordinary air.
Silk is highly hygroscopic. If desiccated at 250° F.
It is exceedingly hygroscopic and corrosive.
The filtrate, now containing roughly two molecules of alumina to one of soda, is concentrated to the original gravity of 1.45, and employed instead of fresh caustic for the attack of more bauxite; the precipitate is then collected, washed till free from soda, dried and ignited at about looo C. to convert it into a crystalline oxide which is less hygroscopic than the former amorphous variety.
It is very hygroscopic, absorbing water with the evolution of hydrochloric acid.
They are crystalline, hygroscopic compounds and are employed for the manufacture of the naphthols.
These sulphides are much less hygroscopic than the corresponding caesium compounds.
It is very hygroscopic and with cold water gives the oxide and hydrochloric acid.
It is more hygroscopic than the tetrachloride; and when treated with much water the bulk is at once decomposed into the blue oxide and hydrochloric acid, but an olive-green solution is also produced.
Cupric oxide, CuO, occurs in nature as the mineral melaconite (q.v.), and can be obtained as a hygroscopic black powder by the gentle ignition of copper nitrate, carbonate or hydroxide; also by heating the hydroxide.
The anhydrous salt is very hygroscopic, and hence finds application as a desiccating agent.
A very striking and remarkable fact, which has much practical interest, is its highly hygroscopic nature.
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.
The long awn, which is bent and closely twisted below the bend, acts as a driving organ; it isvery hygroscopic, the coils untwisting when damp and twisting up when dry.
It is very hygroscopic, and dissolves in water and alcohol.
It is very hygroscopic, dissolves sulphur readily and acts on organic compounds in a manner similar to sulphuric acid.