SODA CAUST1CA - CAUSTIC SODA - HYDRATE OF SODA, NaHO,=40.

Preparation

By evaporating liquor sodae to dryness in a silver or clean iron vessel; the process is conducted as rapidly as possible to prevent absorption of carbonic acid, and plantinum, glass, or porcelain vessels are not admissible because the alkali would act upon them. A pure hydrate is now prepared by decomposing water with metallic sodium.

Characters

Occurs in whitish cakes or pieces which are highly alkaline and corrosive: it is not so deliquescent as potash.

Liquor Sodae - Solution Of Soda

Preparation

By adding slaked lime to hot solution of carbonate of sodium, Na,CO3 + CaH1O2 = CaCO3 + 2NaHO.

Characters

A colorless liquid, of intensely caustic taste, containing nearly 19 gr. of caustic soda to the ounce.

SODAE CARBONAS - CARBONATE OF SODA, Na2CO310H1O, = 286.

Preparation

This is carried out on a large scale for commercial purposes, and is not described in the Pharmacopoeia. The combustion of sea plants formerly furnished us with crude soda-ash, or "barilla," from which the carbonate was prepared, but it is now generally obtained from common salt (chloride of sodium) either by Leblanc's process of treatment with sulphuric acid, to form a sulphate known as "salt-cake," which is strongly heated in a furnace with chalk and charcoal, and afterward the carbonate is crystallized out; or by "the ammonia process," in which the bicarbonate of ammonia precipitates from the salt solution a bicarbonate of soda, and from this the carbonic acid is driven off by heat, to be utilized in other steps of the manufacture.

Characters

Occurs in large rhombic crystals, colorless and transparent when fresh, but readily efflorescing on exposure to air; of nauseous alkaline taste, very soluble in water, not at all in alcohol: they contain 63 per cent. of water of crystallization, which they lose at a sufficient heat. Twenty grains of carbonate of soda neutralize 9.7 gr. of citric and 10.5 of tartaric acid.

Sodoe Carbonas exsiccata, or dried carbonate of soda, being the same salt deprived of water and powdered, is introduced as a separate preparation for convenience in dispensing: 1 gr. = about 2 1/2 gr. of the crystallized salt.

SODAE BICARBONAS - BICARBONATE OF SODA, NaHCO3,=84.

Preparation

By passing a stream of carbonic acid gas into a mixture containing two parts of the crystallized and three parts of the dried carbonate, until the gas ceases to be absorbed. (If the ordinary carbonate only were used, the mass would become too moist, and the crystals too large): by a special arrangement of vessels, the delivery of the carbonic acid is made continuous, as in the case of bicarbonate of potash.

Characters

Occurs in small snow-white grains or scales, or in opaque white powder, slightly alkaline, and somewhat caustic to the taste, permanent in the air, and soluble in water. Good commercial bicarbonate commonly contains 2 or 3 per cent. of carbonate. Twenty grains of the former salt neutralize 16.7 gr. of citric and 17.8 of tartaric acid.

Sodoe Arsenias (v. p. 26).

SODAE SULPHAS - SULPHATE OF SODA - GLAUBER'S SALT, Na2SO410H1O, = 322.

Preparation

In the process for making hydrochloric acid, an acid sulphate of soda is formed by the action of sulphuric acid on common salt, and if this acid sulphate be neutralized with carbonate of soda, the neutral sulphate may be crystallized out.

Characters

Occurs in transparent colorless six-sided prisms, which are deeply channelled; they are efflorescent in the air, and have a saline bitter taste and neutral reaction.

SODAE ACETAS - ACETATE OF SODA, NaC2H3O23H1O, = 136.

Preparation

By neutralizing carbonate of soda with acetic acid: occurs in long striated prisms, which slowly effloresce, and have a sharp, bitter taste.

SODAE HYPOSULPHIS - HYPOSULPHITE OF SODA (SODIC THIOSULPHATE), Na2H1S2O44H1O (NOT OFFICINAL).

Preparation

By warming a solution of the sulphite with powdered sulphur: occurs in large colorless oblique prisms, which are very soluble in water, not in alcohol.

SODAE NITRAS - NITRATE OF SODA, NaNO3,=85.

Preparation

This salt is found native in Peru and Chili, and is purified by crystallization from water. It occurs in the form of obtuse rhomboids, resembling cubes, deliquescent, and very soluble.

SODAE PHOSPHAS - PHOSPHATE OF SODA, Na3HPO412H1O, = 358.

Preparation

Obtained from bone-ash, which is mainly phosphate of lime, by rather a complex process, of which the essential steps are two, viz.: (1) The bone-ash is digested with sulphuric acid, when an acid phosphate is formed and remains in solution, and an insoluble sulphate precipitates. (2) The filtered solution containing the acid phosphate of lime is then treated with carbonate of soda to slight alkalinity, when phosphate of soda is formed, filtered, and re-crystallized.

Characters

Occurs in large, transparent, rhombic prisms, which quickly effloresce in the air; they are faintly alkaline, very soluble in water, and have a mild saline taste.

SODAE HYPOPHOSPHIS - HYPOPHOSPHITE OF SODA, NaPH1O2 = 88.

Preparation

By adding carbonate of soda to solution of hypophos-phite of lime, so long as a precipitate (carbonate of lime) is formed; this is filtered off, and the solution evaporated cautiously.

Characters

A white, crystalline, bitter salt, deliquescent, and very soluble in water and spirit. It readily decomposes, so that explosions occur with it on mixture, for instance, with chlorate of potash and friction; and when heated to redness it ignites, and gives off phosphuretted hydrogen.

SODAE B1BORAS - BORAX, Na2B4O710H1O, = 382.

Preparation

Found native in a crude form in Thibet, India, California, etc.; also prepared by neutralizing boracic acid with carbonate of soda.

Characters

Occurs in flattened semi-transparent prisms, of slightly alkaline reaction and saline taste, soluble in water, and efflorescing in the air. Its solubility is increased by glycerin and by cream of tartar, and from its solutions boracic acid is precipitated by any mineral acid: it gives a green color to flame. When heated it dissolves in its water of crystallization, and at red heat forms a transparent glass much used as a flux for mineral substances in blow-pipe operations.

Liquor Sodae Chloratae - Solution Of Chlorinated Soda

Preparation

By passing washed chlorine gas through a solution of carbonate of soda, till a sp. gr. of 1.06 is reached. The resulting solution contains hypochlorite of soda, with some chloride and bicarbonate of the same.

Characters

A colorless alkaline liquid, with the odor of chlorine, and a pungent taste; sp. gr. 1.103; it bleaches vegetable colors, effervesces with acids, and readily evolves chlorine.

SODII CHLORIDUM - CHLORIDE OF SODIUM - COMMON SALT, NaCl, = 58.5.

Is found native in."rock-salt" and saline waters.

Characters

Occurs in transparent cubes or small white grains, soluble in water, and if pure, permanent in air: deliquescent, if containing chloride of calcium or magnesium.

SODA TARTARATA - TARTARATED SODA - TARTRATE OF SODA AND POTASH - ROCHELLE SALT, NaKC4H1O64H1O, = 282.

Preparation

By adding cream of tartar to a hot strong solution of carbonate of soda, so long as effervescence continues, then filtering and crystallizing.

Characters

Occurs in large, colorless, rhombic prisms, or halves of prisms, which have been compared to tombstones: they are neutral in reaction, soluble in water, and of saline rather bitter taste.

Sodae Citro-Tartras Effervescent - Effervescent Citro-Tartrate Of Soda

Preparation

By mixing bicarbonate of soda with citric and tartaric acids, at considerable heat (200° F.); with constant stirring, this salt is obtained as a granular powder, which effervesces on contact with water.