Precipitated aluminium hydrate finds considerable application in dyeing.
The solution when boiled deposits most of its oxide in the meta-hydrate form.
The hydrate, B1204.2H20, is also known.
It forms a hydrate of composition H 2 S 7H 2 0.
The hydrate, Bi(OH) 3 i is obtained as a white powder by adding potash to a solution of a bismuth salt.
The monoxide and its hydrate are more familiarly known as lime (q.v.) and slakedlime.
In addition to behaving as a basic oxide, aluminium oxide (or hydrate) behaves as an acid oxide towards the strong bases with the formation of aluminates.
If a glucose solution be added to copper sulphate and much alkali added, a yellowish-red precipitate of cuprous hydrate separates, slowly in the cold, but immediately when the liquid is heated; this precipitate rapidly turns red owing to the formation of cuprous oxide.
The corresponding hydrate, Pb(OH)2, is obtained as a white crystalline precipitate by adding ammonia to a solution of lead nitrate or acetate.
On the other hand there are certain forms of ferric hydrate containing less water than limonite and approaching to haematite in their red colour and streak: such is the mineral which was called hydrohaematite by A.
Uranous hydrate is obtained as reddish-brown flakes by precipitating a uranous solution with alkali.
A familiar example is to be found in solutions of sodium sulphate, which may be cooled much below their saturation point and kept in the liquid state till a crystal of the hydrate Na 2 SO 4 IoH 2 O is dropped in, when solidification occurs with a large evolution of latent heat.
The dioxide was obtained as the hydrate, CaO 2.8H,0, by P. Thenard (Ann.
Chim., 1906, 2 5, p. 2 53) considers to be a hydrate of sulphur of composition S $ H 2 0), sulphuric acid, traces of trithionic acid, tetraand pentathionic acids and probably hexathionic acid.
Filter from the bismuth hydrate, and if copper is present, add potassium cyanide till the colour is destroyed, then pass sulphuretted hydrogen, and cadmium is precipitated as the yellow sulphide.
A standard sodium hydrate solution can be prepared by dissolving 42 grammes of sodium hydrate, making up to a litre, and diluting until one cubic centimetre is exactly equivalent to one cubic centimetre of the sulphuric acid.
It crystallizes in prisms which melt at 39° C. A chloral hydroxylamine, CC1 3 [[Choh Nhoh]], melting at 98° C. is obtained by allowing a mixture of one molecular proportion of chloral hydrate with two molecular proportions of hydroxylamine hydrochloride and one of sodium carbonate to stand for some time in a desiccator.
Water when absolutely pure has no action on lead, but in the presence of air the lead is quickly attacked, with formation of the hydrate, Pb(OH) 2, which is appreciably soluble in water forming an alkaline liquid.
(3) Plumbi Carbonas, white lead, a mixture of the carbonate and the hydrate, a heavy white powder insoluble in water; it is not used internally, but from it is made Unguentum Plumbi Carbonatis, strength 1 in so parts of paraffin ointment.
Water, at ordinary or slightly elevated temperatures, is decomposed more or less readily, with evolution of hydrogen gas and formation of a basic hydrate, by (I) potassium (formation of KHO), sodium (NaHO), lithium (LiOH), barium, strontium, calcium (BaH 2 O 2, &c.); (2) magnesium, zinc, manganese (MgO 2 H 2, &c.).
The view, often repeated, that the saccharum of the ancients is the hydrate of silica, sometimes found in bamboos and known in Arabian medicine as tabashir, is refuted by Yule, Anglo-Indian Glossary, p. 654; see also Not.
Titanic oxide separates out as a white hydrate, which, however, is generally contaminated with ferric hydrate and often with tin oxide.
Carbon monoxide takes part in the syntheses of sodium formate from sodium hydrate, or soda lime (at 200 0 -2 20 0), and of sodium acetate and propionate from sodium methylate and sodium ethylate at 160 0 -200°.
Semioxamazide, H 2 N CO CO-NH NH 2, is prepared by the action of hydrazine hydrate on oxamaethane (W.
When a concentrated solution of auric chloride is treated with caustic potash, a brown precipitate of auric hydrate, Au(OH) 3, is obtained, which, on heating, loses water to form auryl hydrate, AuO(OH), and auric oxide, Au 2 0 3.
It is rapidly acted on by water, especially if means are taken to remove the layer of calcium hydrate formed on the metal; alcohol acts very slowly.
Pure potassium is a silvery white metal tinged with blue; but on exposure to air it at once forms a film of oxide, and on prolonged exposure deliquesces into a solution of hydrate and carbonate.
The remaining mud of calcium carbonate and hydrate is washed, by decantation, with small instalments of hot water to recover at least part of the alkali diffused throughout it, but this process must not be continued too long or else some of the lime passes into solution.
The liquors after a concentration in iron vessels are now evaporated in a silver dish, until the heavy vapour of the hydrate is seen to go off.
On crystallizing a solution, the hydrate KOH 2H 2 0 is deposited; 2KOH 9H 2 0 and 2KOH 5H 2 0 have also been obtained.
Werner, four hydrated chromium chlorides exist, namely the green and violet salts, CrC1 3.6H 2 O, a hydrate, CrC1 3.10H 2 O and one CrC1 3.4H 2 0.
HYDRATE, in chemistry, a compound containing the elements of water in combination; more specifically, a compound containing the monovalent hydroxyl or OH group. The first and more general definition includes substances containing water of crystallization; such salts are said to be hydrated, and when deprived of their water to be dehydrated or anhydrous.
This indicates the appearance of a new compound, which should exist pure at E, the next maximum, and, led by these considerations, Roozeboom discovered and isolated a previously unknown hydrate, Fe 2 C1 6 7 H 2 0.
Aluminium hydrate, Al(OH) 3, is obtained as a gelatinous white precipitate, soluble in potassium or sodium hydrate, but insoluble in ammonium chloride, by adding ammonia to a cold solution of an aluminium salt; from boiling solutions the precipitate is opaque.
By drying at ordinary temperatures, the hydrate Al(OH) 3 ï¿½H 2 0 is obtained; at 300° this yields A10(OH), which on ignition gives alumina, Al 2 O 3.
Ferric hydrate, iron soaps and all insoluble impurities are precipitated.
Thus a normal solution of sodium carbonate contains 53 grammes per litre, of sodium hydrate 40 grammes, of hydrochloric acid 36.5 grammes, and so on.
With water it forms a hydrate, and ultimately decomposes into lead dioxide and hydrochloric acid.
Precipitated stannous hydrate dissolves readily in caustic potash; if the solution is evaporated quickly it suffers decomposition, with formation of metal and stannate, 2SnO+2KOH = K2Sn03+Sn+H20.
The chloride readily combines with water to form a crystallizable hydrate SnCl 2.2H 2 O, known as "tin salt" or "tin crystals."
The alkali must be free from carbonate and an excess of it must be avoided, otherwise the hydrate redissolves.
The solution, if boiled, deposits its titanic oxide as a hydrate called metatitanic acid, TiO(OH) 21 because it differs in its properties from orthotitanic acid, Ti(OH) 4, obtained by decomposing a solution of the chloride in cold water with alkalis.
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.
For the fusion of the dry hydrate nickel vessels cannot be used; in fact, even silver is perceptibly attacked as soon as all the excess of water is away; absolutely pure KHO can be produced only in gold vessels.
Taking the point 0 to denote the state of equilibrium between ice, hydrate; saturated solution and vapour, we pass along OA till a new solid phase, that of Na2S04, appears at 32.6°; from this point arise four curves, analogous to those diverging from the point O.
The curve OP represents the varying solubility of the hydrate as the temperature rises from the cryohydric point to 32.6°.
At that temperature crystals of the anhydrous Na 2 SO 4 appear, and a new fixed equilibrium exists between the four phases - hydrate, anhydrous salt, solution and vapour.
As heat is supplied, the hydrate is transformed gradually into the anhydrous salt and water.
At B we have the non-variant cryohydric point at which ice, the hydrate Fe2C16 12H20, the saturated solution and the vapour are in equilibrium at 55° C. As the proportion 26 of salt is increased, the melting point of the con glomerate rises, till, at the -40 maximum point C, we have the pure compound the hydrate with twelve molecules ¦¦ 0.b, E, ?
In a similar way the curve FGH, between 30° and 55°, shows the effect of the hydrate Fe2Cl6.5H20, and the curve HJK that of the hydrate Fe 2 C1 6.4H 2 O, which, when pure, melts at 73.5° - the point J on the diagram.
LIMONITE, or Brown Iron Ore, a natural ferric hydrate named from the Gr.
Limonite is a ferric hydrate, conforming typically with the formula Fe 4 0 3 (OH) 6, or 2Fe 2 O 3.3H 2 O.
The ferric hydrate is also readily deposited from ferruginous waters, often by means of organic agencies.
To ensure this being properly done, the lumps of lime should be broken up small, and enough water to slake them should be added, the lime then being allowed to rest for about forty-eight hours, when the water changes the particles of quicklime to hydrate of lime, and breaks up the hard lumps into a powder.
Chloraloxime, CC1 3 CH: NOH, is obtained when one molecular proportion of chloral hydrate is warmed with four molecular proportions of hydroxylamine hydrochloride and a little water.
Both these soluble hydrates are readily coagulated by traces of a salt, acid or alkali; Crum's hydrate does not combine with dye-stuffs, neither is it soluble in excess of acid, while Graham's compound readily forms lakes, and readily dissolves when coagulated in acids.
Cailletet and later by P. Villard that when allowed to stand in the presence of water at a low temperature a solid hydrate is formed.
GOTHITE, or Goethite, a mineral composed of an iron hydrate, Fe203.H20, crystallizing in the orthorhombic system and isomorphous with diaspore and manganite.
This view was modified by Liebig, who regarded ether as ethyl oxide, and alcohol as the hydrate of ethyl oxide; here, however, he was in error, for he attributed to alcohol a molecular weight double its true value.
Where a solution is likely to change in composition on keeping, such as potassium permanganate, iodine, sodium hydrate, &c., it is necessary to check or re-standardize it periodically.