Chapter LXIV: Part 2 (25)

=Soap, Cro′ton.= _Syn._ SAPO CROTONIS, L. _Prep._ From croton oil and liquor of potassa, equal parts; triturated together in a warm mortar until they combine. Cathartic.——_Dose_, 1 to 3 gr.

=Soap of Gamboge.= _Syn._ SAPO GAMBOGIÆ. (Soubeiran.) _Prep._ Mix 1 part of gamboge with 2 of soap, dissolve it with a little spirit, and evaporate to a pilular consistence.

=Soap, of Gua′iacum.= _Syn._ SAPO GUAIACI, SAPO GUAIACINUS, L. _Prep._ (Ph. Bor.) Liquor of potassa, 1 oz.; water, 2 oz.; mix in a porcelain capsule, apply heat, and gradually add of resin of guaiacum (in powder), 6 dr., or as much as it will dissolve; next decant or filter, and evaporate to a pilular consistence.——_Dose_, 10 to 30 gr.; in chronic rheumatism, various skin diseases, &c.

=Soap I′odine.= _Syn._ SAPO IODURATUS, L. _Prep._ From Castile soap (sliced), 1 lb.; iodide of potassium, 1 oz.; (dissolved in) water, 3 fl. oz.; melt them together in a glass or porcelain vessel, over a water bath. Excellent in various skin diseases; also as a common soap for scrofulous subjects.

=Soap of Jal′ap.= See JALAP, SOAP OF.

=Soap, Larch.= _Syn._ SAPO LARICIS. (Dr Moore.) _Prep._ Dissolve 12 oz. of white curd soap in 24 oz. of rose water on a steam bath. Infuse 4 oz. of wheat bran in 10 oz. of cold water for 24 hours, and express. Add to the last, 3 oz. of pure glycerin. Dissolve 6 dr. of extract of larch bark in 1 oz. of boiling water. Mix these solutions with the dissolved soap, evaporate over a steam bath to a proper consistence, and pour into moulds to cool. For the local treatment of psoriasis.

=Soap, Macquer’s Acid.= _Syn._ SAPO VITRIOLICUS, L. _Prep._ From Castile soap, 4 oz.; softened by heat and a little water, and then continually triturated in a mortar with oil of vitriol (added drop by drop). Detergent. Used where alkalies would be prejudicial.

=Soap, Marine.= _Patent._ This is made by substituting cocoa nut oil for the fats and oils used in the manufacture of common soap. It has the advantage of forming a lather with salt water.

=Soap, Mercu′′rial.= _Syn._ SAPO HYDRARGYRI. (M. Herbert.) 1. _Prep._ Dissolve 4 oz. of quicksilver in its weight of nitric acid without heat; melt in a porcelain basin by water bath 18 oz. of veal suet, and add the solution, stirring the mixture till the union is complete. To 5 oz. of this ointment, add 2 oz. of solution of caustic soda (1·33), porphyry slag, till a soap is formed, which is completely soluble in water. For external use, alone, or dissolved in water, in some cutaneous diseases.

2. SAPO MERCURIALIS, L. _Prep._ (SAPO SUBLIMATIS CORROSIVI.) From Castile soap (in powder), 4 oz.; corrosive sublimate, 1 dr.; (dissolved in) rectified spirit, 1 fl. oz.; beaten to a uniform mass in a porcelain or wedgwood-ware mortar.

3. (SAPO HYDRARGYRI, PRECIPITATI ALBI——Sir H. Marsh.) _Prep._ Beat 12 oz. of white Windsor soap in a marble mortar, add 1 dr. of rectified spirit, 2 dr. of white precipitate, and 10 drops of otto. Beat the whole to a uniform paste.

4. (SAPO HYDRARGYRI, PRECIPITATI RUBRI——Sir H. Marsh.) From white Windsor soap, 2 oz.; nitric oxide of mercury (levigated), 1 dr.; otto of roses, 6 or 8 drops; (dissolved in) rectified spirit, 1 to 2 fl. dr.; as the last. Both the above are employed as stimulant detergents and repellants, in various skin diseases; also as SAVON ANTISYPHILITIQUE.

=Soap of Subacetate of Lead.= _Syn._ SAPO SATURNI (Bristol Infirmary). _Prep._ Boil 1 lb. of white soap in 4 pints of rain water; when the soap is dissolved add 1 oz. of camphor pulverised with spirit, and mixed with 2 oz. of liquid subacetate of lead, stir the whole till cold.

=Soap, Sul′phuretted.= _Syn._ SAPO SULPHURIS, SAPO SULPHURATUS, L. _Prep._ (Sir H. Marsh.) From white soap, 2 oz.; sublimed sulphur, 1/4 oz.; beaten to a smooth paste in a marble mortar with 1 or 2 fl. dr. of rectified spirit strongly coloured with alkanet root, and holding in solution otto of roses, 10 or 12 drops. In itch and various other cutaneous diseases.

=Soap, Tar.= _Syn._ SAPO PICIS LIQUIDÆ, SAPO PICEUS, L. _Prep._ From tar, 1 part; liquor of potassa and soap (in shavings), of each 2 parts; beat them together until they unite. Stimulant. Used in psoriasis, lepra, &c.

=Soap, Tur′pentine.= _Syn._ STARKEY’S SOAP; SAPO TEREBINTHINÆ, S. TEREBINTHINATUS, L.; SAVON TÉRÉBINTHINE, Fr. _Prep._ (P. Cod.) Subcarbonate of potash, oil of turpentine, and Venice turpentine, equal parts; triturate them together, in a warm mortar, with a little water, until they combine; put the product into paper moulds, and in a few days slice it, and preserve it in a well-stopped bottle.

=SOAPS (Toilet).= Of toilet soaps there are two principal varieties:——

1. (Hard.) The basis of these is, generally, a mixture of suet, 9 parts, and olive oil, 1 part, saponified by caustic soda; the product is variously scented and coloured. They are also made of white tallow, olive, almond, and palm-oil soaps, either alone or combined in various proportions, and scented.

2. (Soft.) The basis of these is a soap made of hog’s lard and potash, variously scented and coloured.

3. Guido Schnitzer, writing to ‘Dingler’s Journal’ (cciii, 129-132),[173] says that the use of sodium silicate (ordinary water-glass) has proved of great value in the manufacture of palm oil and cocoa-nut oil soaps, as it increases their alkalinity, and gives to them greater hardness and durability. It is for these reasons the silicate is much used in the manufacture of toilette soaps.

[Footnote 173: ‘Journ. of Chem. Soc.,’ new series, vol. x.]

He states that during the American war, when the price of resin soap reached a high price, sodium silicate was much used as a substitute in soap making. The soap is found to be the more active and durable in proportion to the amount of silica in the silicate.

Schnitzer made a series of experiments in order to discover a mixture which, on fusing, will yield a silicate as rich as possible in silica, without being insoluble in boiling water, and he found the following proportions yielded on fusion the best silicate for the above purposes:——

100 parts of soda ash (containing 91 per cent, of Na_{2}CO_{3}), and 180 of sand. In the solution of silicate obtained on treatment with boiling water, the proportion of the Na_{2}O to the SiO_{2} would then be as 1 to 2·9.

After long boiling with water, there ordinarily remains a slimy residue, which, on boiling up with fresh dilute soda-lye for a long time, furnishes a concentrated solution of silicate. This residue, consisting of silica, with insoluble higher silicates, was boiled with soda solution at 6° Baume, and the solution concentrated to 40° Baume, when the proportion therein of Na_{2}O to SiO_{2} was found to be as 1 to 1·, and on cooling those crystallised out, sodium silicate of the formula Na_{2}SiO_{3} × 8H_{2}O, in white foliated crystals.

On the small scale the perfume is generally added to the soap melted in a bright copper pan by the heat of a water bath; on the large scale it is mixed with the liquid soap, at the soap-maker’s, before the latter is poured into the frames.

The following are examples of a few of the leading toilet soaps:[174]

[Footnote 174: See also SAVONETTES.]

=Soap, Bitter Al′mond.= _Syn._ SAVON D’AMANDE, Fr. _Prep._ From white tallow soap, 56 lbs.; essential oil of almonds, 3/4 lb.; as before.

=Savon au Bouquet.= [Fr.] _Prep._ From tallow soap, 30 lbs.; olive-oil soap, 10 lbs.; essence of bergamot, 4 oz.; oils of cloves, sassafras, and thyme, of each 1 oz.; pure neroli, 1/2 oz.; brown ochre (finely powdered), 1/2 lb.; mixed as the last.

=Soap, Cin′namon.= _Prep._ From tallow soap, 14 lbs.; palm-oil soap, 7 lbs.; oil of cinnamon (cassia), 3 oz.; oil of sassafras and essence of bergamot, of each 1/2 oz.; levigated yellow ochre, 1/2 lb.

=Soap, Float′ing.= _Prep._ From good oil soap, 14 lbs.; water, 3 pints; melted together by the heat of a steam or water bath, and assiduously beaten until the mixture has at least doubled its volume, when it must be put into the frames, cooled, and cut into pieces. Any scent may be added.

=Soap, Glycerin.= Any mild toilet soap being liquefied, glycerin is intimately mixed with it in the proportion of from a 20th to a 25th of the weight of the soap. Sometimes a red, and others an orange tint is given to it. The scent usually consists of bergamot, or rose geranium, mixed with a little oil of cassia, to which sometimes a little oil of bitter almonds is added.

2. (Spon.) 40 lbs. of tallow, 40 lbs. of lard, and 20 lbs. of cocoa-nut oil, are saponified with 45 lbs. of soda lye, and 5 lbs. of potash lye, of 40° Baume, when the soap is to be made in the cold way. To the paste then add, pure glycerin 6 lbs., oil of Portugal, 1/2 oz., oil of bergamot, 1/3 oz., bitter almond oil, 5 oz., oil of vitivert, 3 oz.

=Soap, Hon′ey.= _Prep._ 1. From palm-oil soap and olive-oil soap, of each 1 part; curd soap, 3 parts; melted together and scented with the oil of verbena, rose-geranium, or ginger-grass.

2. From the finest bright-coloured yellow soap, scented with the oils of ginger-grass and bergamot.

=Soap, Liquid Glycerin——Glycerinseife, Flüssige.= Sesame or cotton-seed oil is saponified with sufficient caustic potash, and while moist is dissolved in six times its weight of spirit of wine. The solution is filtered, five-sixths of the spirit is distilled from a water bath, and the cooled residue is reduced to the consistence of thin honey, with a mixture of 2 parts glycerin and 1 part spirit. It is then perfumed.

=Soap, Musk.= 1. A good ox suet or tallow soap is generally used for the basis of this. The scent is composed of a mixture of essence of musk, with small quantities of the oils of bergamot, cinnamon, and cloves. The quantity of musk must be regulated by the amount of fragrance required. The soap is usually coloured with caramel.

2. Another kind is made with tallow and palm-oil soap, to which is added a mixture of the powders of cloves, roses, and gilliflowers, oil of bergamot, and essence of musk. The colouring matter is brown ochre.

=Soap, Musk.= As CINNAMON SOAP, but with essence of musk, supported with a little essence of bergamot and oil of cloves, as perfume, and burnt sugar, to colour.

=Soap, Naples.= From olive oil and potash.

=Soap, Orange-flower.= As SAVON À LA ROSE, with oil of neroli or essence de petit grain, supported with a little of the essence of ambergris and Portugal, for perfume.

=Soap, Palm-oil.= _Syn._ VIOLET SOAP. Made of palm oil and caustic soda lye. It has a pleasant odour of violets and a lively colour.

=Soap, Pearl.= _Syn._ ALMOND CREAM; CRÊME D’AMANDES, Fr. _Prep._ From a soap made of lard and caustic potash lye; when quite cold it is beaten in small portions at a time in a marble mortar, until it unites to form a homogeneous mass, or ‘pearls,’ as it is called; essence of bitter almonds, q. s., to perfume, being added during the pounding.

=Savon à la Rose.= [Fr.] _Prep._ From a mixture of olive-oil soap, 36 lbs.; best tallow soap, 24 lbs. (both new and in shavings); water, 1 quart; melted in a covered bright copper pan, by the heat of a water bath, then coloured with vermilion (finely levigated), 2-1/2 oz.; and, after the mixture has cooled a little, scented with otto of roses, 3 oz.; essence of bergamot, 2-1/2 oz.; oil of cloves and cinnamon, of each 1 oz.

=Soap, Rondeletia.= This is merely cinnamon soap scented with the essence made with mixed essential oils, &c., known as rondeletia. It is coloured with brown or yellow ochre.

=Soap, Sha′′ving.= See PASTE (Shaving).

=Soap, Transpa′′rent.= _Prep._ From perfectly dry almond, tallow, or soft soap, reduced to shavings, and dissolved, in a closed vessel or still, in an equal weight of rectified spirit, the clear portion, after a few hours’ repose, being poured into moulds or frames; after a few weeks’ exposure to a dry atmosphere, the pieces are ‘trimmed up’ and stamped, as desired. It may be scented and coloured, at will, by adding the ingredients to it while in the soft state. A rose colour is given by tincture of archil; and yellow, by tincture of turmeric or annotta. It does not lather well.

=Soap, Windsor.= _Syn._ SAPO VINDESORÆ, S. VINDESORIENSIS, L. _Prep._ 1. (WHITE; S. V. ALBUS.) The best ‘English’ is made of a mixture of olive oil, 1 part, and ox tallow or suet, 9 parts, saponified by caustic soda. ‘French Windsor-soap’ is made of hogs’ lard, with the addition of a little palm oil. That of the shops is merely ordinary curd soap, scented with oil of caraway, supported with a little oil of bergamot, lavender, or origanum. To the finer qualities a little of the essences of musk and ambergris is occasionally added. 1-1/2 lb. of the mixed scents is the common proportion per cwt.

2. (BROWN; S. V. FUSCUS.) This merely differs from the last in being coloured with burnt sugar, or (less frequently) with umber. Originally it was the white variety, that had become mellow and brown with age.

=SO′DA.= See SODIUM.

=SO′DIUM.= Na. _Syn._ NATRIUM. The metallic base of soda. It was first obtained by Sir H. Davy, in 1807, by means of a powerful galvanic battery; but it may be more conveniently and cheaply procured, in quantity, by the method described under POTASSIUM. The process, when well conducted, is, however, much easier and more certain than that for the last-named metal.

_Prep._ The anhydrous carbonate of sodium, 6 parts, is dissolved in a little water, and the solution mixed with charcoal in fine powder, 2 parts, and charcoal in small lumps, 1 part; the whole is then evaporated to dryness, transferred to an iron retort, and treated in the manner described at page 1353.

_Obs._ Very important improvements have been made in the manufacture of this metal by Deville, consisting partly in the simplification of the receiver, and partly in the addition of carbonate of calcium to the mixture, which addition appears to facilitate the reduction of the sodium in a most remarkable manner.

_Prop., &c._ Sodium is a soft silver-white metal, scarcely solid at common temperatures, fuses at 194° Fahr., and volatilises at a red heat; it oxidises very rapidly in the air; when placed on the surface of cold water, it decomposes that liquid with great violence, but generally without flame, in which it differs from potassium; on hot water it burns with a bright yellow flame——in both cases a solution of pure soda being formed. Sp. gr. ·972; it is more malleable than any other metal, and may be easily reduced into very thin leaves (Ure); its other properties resemble those of potassium, but are of a feebler character. With oxygen it forms two oxides; with chlorine, a chloride (common salt); and——with bromine, iodine, fluorine, &c., bromide, iodide, fluoride, &c., all of which may be obtained by similar processes to the respective compounds of potassium, which, for the most part they resemble.

_Uses._ Until recently sodium has been regarded as a mere mechanical or philosophical curiosity; it has now, however, become of great practical importance, from being employed in the manufacture of the metals aluminium, magnesium, &c.

_Tests._ Sodium salts are recognised by their solubility in water, and by their giving a precipitate with none of the ordinary reagents. They give a rich yellow colour to the colourless Bunsen or the pale blue blowpipe flame. They can, to a certain extent, be also distinguished from potassium salts by the carbonate being an easily crystallisable salt, effervescing in dry air; the carbonate of potassium being crystallised with difficulty, and deliquescent. Platinum chloride does not give a precipitate with sodium chloride; neither does picric acid, perchlorate of ammonium, nor tartaric acid.

=Sodium, Acetate of.= NaC_{2}H_{3}O_{2}. _Syn._ ACETATE OF SODA; SODÆ ACETAS (B. P., Ph. D.), L. Prepared from carbonate of sodium as the corresponding potassium salt; but the resulting solution is evaporated to a pellicle, and set aside to crystallise. Its crystals are striated oblique rhombic prisms; it effloresces slightly in the air, and is soluble in 4 parts of water at 60° Fahr. Diuretic.——_Dose_, 20 to 40 gr.

=Sodium, Aluminate.= This salt has of late been in extensive demand by the calico printer and dyer. In France it is obtained from banxite, a native hydrate of aluminate, by treatment with caustic or carbonate of soda. If caustic soda be employed, the powdered banxite is boiled with a solution of the alkali, whereas if carbonate of soda be used, it is fused with the banxite in a reverbatory furnace. By the first process the resulting aluminate of soda is dissolved in water, and evaporated to dryness, forms the commercial article. If prepared by ignition, the semifused mass is lixiviated with water, and then evaporated to dryness. Aluminate of soda prepared as above occurs as a white powder, of a greenish-yellow hue, and dry to the touch.

It is equally soluble in both hot and cold water, and readily decomposed by carbonic and acetic acids, bicarbonate and acetate of soda, chloride of ammonia, &c. Dr Wagner states that it is used for the preparation of lake colours, the induration of stone, in the manufacture of artificial stone, and for the saponification of fats in the manufacture of stearin candle manufacture, also in the preparation of an opaque, milky-looking glass, or semi-porcelain.

Aluminate of soda may likewise be procured from cryolite, as described under ALUM.

=Sodium Arseniates.= _Syn._ SODÆ ARSENIAS (B. P.). Arsenious acid, 10 oz.; nitrate of soda, 8-1/2 oz.; dried carbonate of soda, 5-1/2 oz.; boiling distilled water, 35 fl. oz. Reduce the dry ingredients separately to fine powder, and mix them thoroughly in a porcelain mortar. Put the mixture into a large clay crucible and cover it with the lid. Expose it to a full red heat till all effervescence has ceased, and complete fusion has taken place. Pour out the fused salt on a clean flagstone, and as soon as it has solidified and while it is still warm put it into the boiling distilled water, stirring diligently. When the salt has dissolved filter the solution through paper, and set it aside to crystallise. Drain the crystals, and having dried them rapidly on filtering paper, enclose them in a stoppered bottle.

=Sodium, Benzoate.= _Syn._ SODÆ BENZOAS. (B. Cod.) _Prep._ Heat gently benzoic acid and water, and add caustic soda, q. s. to neutralise the acid. Filter, evaporate, and crystallise over sulphuric acid under a bell-glass.

=Sodium, Bisulphate.= _Syn._ ACID SULPHATE, SODÆ BISULPHIS. _Prep._ Dissolve crystallised carbonate of soda in twice its weight of water, and pass sulphurous acid in excess through the solution. Set it aside to crystallise. Its solution is used to preserve subjects.

=Sodium, Bromide of.= _Syn._ SODII BROMIDUM. Prepared as bromide of potassium.

=Sodium, Carbonate of.= Na_{2}CO_{3}. 10Aq. _Syn._ CARBONATE OF SODA, MONO-CARBONATE OF SODA, SUBCARBONATE OF S.†, Salt of barilla†; SODÆ CARBONAS (B. P., Ph. L., E., & D.), L. The carbonate of sodium of commerce (WASHING SODA) was formerly prepared from the ashes of seaweed, and other marine vegetables, in a somewhat similar manner to that by which carbonate of potassium is obtained; but it is now usually obtained from chloride of sodium by the action of heat, sulphuric acid, and carbonaceous matter.

_Prep._ 1. (From common salt or sulphate of sodium.) The latter is generally obtained by decomposing the former with sulphuric acid, the evolved gas being passed into water, or through flues filled with coke, over which a very small stream of cold water constantly flows, by which it is condensed, and forms ‘LIQUID HYDROCHLORIC ACID,’ a substance afterwards consumed, in large quantities, in the manufacture of chloride of lime, and for other purposes. The sulphate of sodium, obtained from this or any other source, is well mixed with an equal weight of chalk or limestone, and about half its weight of small coal, each being previously ground to powder, and the mixture is exposed to a strong heat in a ‘reverbatory furnace’ (see _engr._) until the decomposition of the sulphate is complete, the mass during the calcination being frequently stirred about with a long iron rod; the semi-liquid is now raked into an iron trough, where it is allowed to cool, whilst the furnace is recharged with fresh materials. The crude dark-grey product, thus obtained, is known as ‘ball alkali,’ or ‘British barilla,’ and usually contains about 22 or 23% of pure hydrate of sodium. This is now lixiviated with tepid water, and the solution, after defecation, evaporated to dryness; the residuum is mixed with a certain quantity of sawdust, coal-dust, or charcoal, and roasted in a reverberatory furnace, at a heat not exceeding 700° Fahr., until all the sulphur is expelled. The product is the ‘soda-ash,’ ‘soda salt,’ or ‘British alkali,’ of commerce, and contains about 50% of pure sodium, partly in the state of carbonate, and partly as hydrate, the remainder being chiefly sulphate of sodium and common salt. When this is purified by solution in water, defecation, evaporation, and crystallisation, it furnishes commercial crystallised carbonate of soda. When this last is redissolved, and the filtered solution is carefully crystallised, it constitutes the ordinary carbonate of sodium used in pharmacy and medicine.

Another process for the preparation of commercial carbonate of sodium, known as the ‘ammonia process,’ has of late years met with considerable adoption. The history of this process, together with the process itself, are thus described by Dr R. Wagner:[175] “Six years ago (he was writing in 1873), when the international jury at the Paris Exhibition expressed their opinion upon the state of the soda industry at that time, all the judges, whether practical or theoretical men, believed that Leblanc’s process (that previously described) would hold the field for a long time yet. This seemed still more probable, since a process had just been introduced for recovering the sulphur from the soda residues. At that time all the soda in use was prepared by this process, excepting a comparatively small amount obtained from Chili saltpetre and cryolite, although there were already tangible indications that soda could be made on a larger scale by another method, which would be cheaper than Leblanc’s process.

[Footnote 175: ‘Journal of Applied Chemistry.’]

“The chemical section of the international jury at the Vienna Exposition, under the presidency of Professor A. W. Hofmann, constituted a congress of chemical technology. By its labours during the course of the summer this congress of scientific men was able to authenticate the very important fact that although Leblanc’s process might in the future possess some importance for certain branches of the industry, yet in most places another soda process would be introduced in the immediate future, and entirely supersede that of Leblanc. Since the time of the Paris Exhibition this new process has grown from a small germ to a strong tree.

“The process in question, and which is called by Professor Hofmann ‘the ammonia process,’ is not new, from either a chemical or scientific point of view. It belongs to the same methods as those in which oxide of lead, bicarbonate of magnesia, quicklime, alumina, silicate of alumina, oxide of chromium, or fluosilicic acid are employed to decompose chloride of sodium, and convert it directly into soda or its carbonate. None of these attempts met with a success deserving of notice; although for a century past efforts have been made to render them practically operative. The new process is founded upon a reaction noticed over thirty years ago——that of bicarbonate of ammonia upon a strong solution of common salt. The greater part of the sodium is precipitated as bicarbonate, while chloride of ammonium remains in solution, from which the ammonia for a second operation is expelled by quicklime. The carbonic acid necessary to convert the ammonia into bicarbonate of ammonia, and thus make the process a continuous one, is obtained by heating the bicarbonate of soda to convert it into the simple carbonate.

“The sensation which the ammonia process has created in industrial circles will render a brief history of its development not uninteresting.

“So far as I know, Harrison, Dyer, Grey, and Hemming were the first to patent the ammonia process in Great Britain in 1838. Great expectations were excited by it, but it soon sank into oblivion.

“Thirty or forty years ago the manufacture of soda was by no means at the head of the great branches of industry; at that time, too, ammonia was not to be had cheaply and in immense quantities, and that branch of machine building which has furnished the necessary apparatus for chemical industries did not exist. Besides this, Anton, of Prague, in 1840, claimed to have proved that in the ammonia process a very considerable portion of the common salt still remained undecomposed.

“After a sleep of sixteen years the ammonia process again entered the field. On the 26th of May, 1854, Turck took out a patent in France, and on the 21st June, the same year, Schlœsing, chemist of the Imperial Tobacco Factory at Paris, took out a patent for France and Great Britain. The mechanical portion and machinery for Schlœsing’s process were designed by Engineer E. Rolland, director of the tobacco factory. In 1855 a company was organised to work this process. An experimental manufactory was started at Puteaux, near Paris, but, owing to its situation and arrangements, as well as the salt monopoly, it could not produce soda cheap enough to compete with the other process, and hence, in 1858, the experiment was abandoned. Schlœsing and Rolland were of the opinion that sooner or later the new process must come into use in making soda.

“It must here be noticed that in 1858 Professor Heeren, of Hanover, subjected the ammonia process to a very careful test in his laboratory.

“From his experiments and calculations it was ascertained that this process was better adapted to the manufacture of the bicarbonate than of the simple protocarbonate of soda.

“To render this sketch more complete and historically true, it must be mentioned that T. Bell, of England, took out a patent, Oct. 13th, 1857, for a new soda process, which in principle and practice was almost literally the same as that of Dyer.

“It was known when the jury was working at Paris in 1867 that essential improvements had been introduced into the ammonia process by the efforts of Marguerite and De Sourdeval, of Paris, and James Young, of Glasgow. A more important fact, however, is that Solvay and Co., of Conillet, in Belgium, actually exhibited at the Paris Exhibition carbonate of soda prepared by this new process.

“Since that time the ammonia process has been developed and perfected to such an extent, especially by Solvay, Honigmann, and Prof. Gerstenhœfer, that as early as February, 1873, A. W. Hofmann, in his introduction to the third group of the catalogue of the Exhibition of the German Empire, was able to make this remark:——‘At all events the ammonia process is the only one which threatens to become an important competitor of the now also most exclusively employed process of Leblanc.’ The Vienna Exposition has since proved the truth of this assertion.

“There are now large works in England, Hungary, Switzerland, Westphalia, Thueringia, and Baden, which employ the improved ammonia process, and some of them make fifteen tons of soda per day.

“The advantages of the new process over that of Leblanc are very evident, although the details of the process have not yet been made public.

“The chief advantage consists in the direct conversion of salt into carbonate of soda, and next from the fact, that from a saturated brine only the sodium is precipitated, with none of the other metals of the mother liquor. Besides this, the product is absolutely free from all sulphur compounds, the soda is of a high grade, the apparatus and utensils are very simple, there is a great saving of labour and fuel, and no noxious gases and waste products are produced, which is of importance from a sanitary point of view. The only weak point of the ammonia process is the loss of chlorine, which is converted into worthless chloride of calcium.

“The effect which the general introduction of the new soda process will exert upon large chemical industries in general, and especially upon the consumption of sulphur, the manufacture of sulphuric acid, and chloride of lime, cannot be overlooked.”

3. Another method for the direct preparation of soda and potash from their chlorides is described in the ‘Bayerisches Industrie und Gewerbe Blatt.’[176] The process is thus described by its author, Herr E. Bohlig:

[Footnote 176: ‘New Remedies,’ 1878, 4.]

1. Magnesium oxalate (freshly prepared when newly starting, but, after the first operation, obtained as a dry product in the next step) is allowed to drain, and then mixed in a large vat with the proper quantities of sodium chloride, or concentrated brine and hydrochloric acid, after which it is allowed to stand a few hours. Decomposition takes place almost instantaneously; all the magnesium goes into solution in form of syrupy magnesium chloride, while all the sodium and oxalic acid are deposited as a crystalline acid salt (acid sodium oxalate, or binoxalate of sodium).

Since the magnesium oxalate is always obtained of the same composition and in the same quantity, it is sufficient to determine its weight once for all, and to take each time the previously common amounts of common salt. The acid need not be weighed either; it must be added in just sufficient quantity to destroy the milky appearance which the mixture first assumes.

The reaction is as follows:

MgC_{2}O_{4} + HCl + NaCl = NaHC_{2}O_{4} + MgCl_{2}

Magnesium + Hydrochloric + Sodium = Sodium Magnesium
oxalate. acid. chloride. binoxalate. chloride.

The crystalline powder of sodium binoxalate is transferred to large draining filters, washed with water until the acid solution of magnesium chloride is removed, and worked up, as below described, while still moist.

The acid solution of magnesium chloride is made use of several times in succession as so much hydrochloric acid, together with a quantity of fresh acid sufficient for the reaction. Finally, when the magnesium chloride has inconveniently accumulated, it is worked up by itself into magnesia and hydrochloric acid.

2. In order to obtain the soda, the sodium binoxalate is brought together with an equivalent quantity of magnesium carbonate and water in a tight cask. As soon as the remaining air has been nearly expelled by the generated carbonic acid gas, the cask is closed, and a stirring mechanism set in motion.

A pressure gauge attached to the cask indicates a gradual rise of the pressure to two atmospheres, but, on continual stirring, this diminishes, until, finally, the gauge stands again at 0°. The cask now contains a concentrated solution of sodium bicarbonate, and a precipitate of magnesium oxalate, which latter, being coarsely granular, is easily separated from the liquid, and is used over again, after washing, for a new operation.

The solution of sodium bicarbonate is boiled for a short time with magnesia, obtained in distilling magnesium chloride, and both are thereby converted into simple carbonates. Both reactions are shown in the following scheme:

1. NaHC_{2}O_{4} + MgCO_{3} = NaHCO_{3} + MgC_{2}O_{4}

Sodium + Magnesium = Sodium Magnesium
binoxalate. carbonate. bicarbonate. oxalate.

2. 2NaHCO_{3} + MgO = Na_{2}CO_{3} + MgCO_{3} + H_{2}O

Sodium + Magnesia. = Sodium + Magnesium + Water
bicarbonate. carbonate. carbonate.

As the solution of sodium carbonate, after concentration to 40°B., is incapable of dissolving or retaining in solution any sodium oxalate, it follows that the whole of the oxalic acid is recovered. The magnesia which is required for the purpose is obtained by distilling magnesium chloride, which thereby splits up into hydrochloric acid and magnesia. One half of the latter receives, as we have seen, its carbonic acid by boiling with sodium bicarbonate; the other half is placed, whilst still moist, upon trays in great wooden closets, through which the gases of the furnace pass, and is thereby carbonated. The process may also be so modified that the sodium binoxalate is first decomposed by caustic magnesia, and that magnesium carbonate is afterwards added.

The whole mixture is then transferred to a stirring cask, provided with openings for the passage of cooled furnace gases, whereby the caustic soda present is very soon carbonated.

3. As soon as a large quantity of magnesium chloride solution has accumulated, it is tested as follows:——A small sample is mixed, while boiling, with magnesium oxalate, as long as the latter is dissolved, and then allowed to cool. There should be no crystalline deposit of sodium binoxalate formed, a proof that the solution does not contain any sodium chloride in excess, and is fit for distillation. It is first neutralised by adding some more magnesia, and evaporated over a naked fire in large kettles to a doughy consistence, short of driving off the hydrochloric acid. It is then transferred into the ordinary soda furnace, where it is distilled with a moderate fire. The eliminated hydrochloric acid is condensed in the usual manner.

The residuary mass should not be heated red hot, so as not to impair its porosity or its ready affinity for carbonic acid. If, however, the first-mentioned test shows the magnesium chloride to contain sodium chloride the whole mass must be mixed with magnesium oxalate, and after removal of the precipitated sodium oxalate, saturated with magnesia and distilled. The same process, in all its details, may also be employed for the manufacture of potassa and its carbonate.

4. Another method of manufacture of commercial soda is by treating the mineral cryolite (a double fluoride of sodium and aluminium) with either caustic, or hydrate of lime. The results of the reaction are caustic soda, sodium aluminate, and calcium fluoride.

The aluminate and caustic soda being both soluble in water, a stream of carbonic acid is passed through the solution containing them, whereby all the soda becomes converted into carbonate, whilst the alumina is thrown down as an insoluble precipitate. In the wet way, if enough hydrate of lime be employed, all the soda may be obtained in the caustic condition.

This process is largely used in Germany. Various other processes for the manufacture of commercial soda have been devised, some of which are still followed, whilst others, being impracticable, have collapsed.

Mr Kingzett, in his work on the alkali trade, has described most of them.

When anhydrous carbonate of sodium is required (SODÆ CARBONAS EXSICCATA, B. P., Ph. L.; SODÆ CARBONAS SICCATUM, Ph. E. & D.), the crystallised carbonate is heated to redness, and, when cold, powdered.

_Prop., &c._ Carbonate of sodium forms large, transparent, oblique rhombic prisms, which, as ordinarily met with, and of the formulæ Na_{2}CO_{3}.10Aq; but by particular management may be had with fifteen, nine, seven, or sometimes with only one molecule of water of crystallisation (Fownes); it is soluble in twice its weight of water at 60°, and less than an equal weight at 212° Fahr. As a medicine it is deobstruent and antacid, and is given in doses of 10 to 30 gr. It is also, occasionally, used to make effervescing draughts. When taken in an overdose it is poisonous. The antidotes are the same as for carbonate of potassium. The crude carbonate is largely employed in the manufacture of soap, glass, &c.

Fifty three gr. of the dried carbonate are equal to 143 of the crystallised salt. The medicinal properties of both are similar. It has, however, the disadvantage of being difficultly soluble in water.

The ordinary carbonate of sodium generally contains either sulphates or chlorides, or both; and these may be detected as under CARBONATE OF POTASSIUM. “When supersaturated with nitric acid, it precipitates only slightly, or not at all, chloride of barium or nitrate of silver; and 143 gr. require at least 960 grain-measures of solution of oxalic acid” (B. P.). At a high temperature 100 gr. lose 62·5 gr. of water.

=Sodium, Bicarbonate of.= NaHCO_{3}. _Syn._ SESQUICARBONATE OF SODA, SODÆ BICARBONAS (B. P., Ph. L., E., & D.). This salt can be prepared in exactly the same manner as the corresponding salt of potassium. Another method is as follows:——Take of crystallised carbonate of sodium, 1 part; dried carbonate of sodium, 2 parts (both in powder); triturate them well together, and surround them with an atmosphere of carbonic acid gas, under pressure; let the action go on until no more gas is absorbed, which will generally occupy 10 to 14 hours, according to the pressure employed, then remove the salt, and dry it at a heat not above 120° Fahr.

_Prop., &c._ A crystalline white powder; it is soluble in 10 parts of water at 60° Fahr., but it cannot be dissolved in even warm water without partial decomposition; it is more pleasant tasted and more feebly alkaline than the carbonate of the same base. When absolutely pure it does not darken turmeric paper, or only very slightly. The dose is from 10 to 40 gr., as an antacid and absorbent. It is much employed in the preparation of effervescing powders and draughts, for which purpose

20 gr. of commercial bicarbonate of sodium
\------------------\/--------------------/
are taken with
/------------------/\---------------\
18 gr. of crystallised tartaric acid;

17 gr. of crystallised citric acid; or

1/2 fl. oz. of lemon juice.

The quantity of bicarbonate any given sample contains may be approximately determined by well washing 100 gr. of the salt with an equal weight of water, and filtering the solution. The residuum left upon the filter, dried at a heat of 120° Fahr., and weighed, gives the per-centage of pure bicarbonate of sodium present (very nearly). The solution of this in water will give only a very trifling white precipitate with corrosive sublimate; whilst the filtered portion, which was used to wash the salt, will give a red one, if it contains the simple carbonate of sodium.

=Sodium, Chloride of.= NaCl. _Syn._ SODII CHLORIDUM (B. P., Ph. L., & D.), SODÆ MURIAS (Ph. E.), L. This important and wholesome compound appears to have been known in the earliest ages of which we have any record. It is mentioned by Moses (Gen. xix, 26), and by Homer in the Iliad (lib. ix, 214). In ancient Rome it was subjected to a duty (_vectigal salinarium_); and even at the present day a similar tax furnishes no inconsiderable portion of the revenue of certain nations. Common salt forms no small portion of the mineral wealth of England, and has become an important article of commerce in every part of the known world. The principal portion of the salt consumed in this country is procured by the evaporation of the water of brine springs. It is also prepared by the evaporation of sea-water (hence the term ‘sea-salt’), but this process has been almost abandoned in England, being more suited to hot dry climates or to very cold ones.

_Var._ BAY SALT; SAL MARINUS, SAL NIGER; imported from France, Portugal, and Spain, and obtained from sea-water evaporated in shallow ponds by the sun; large-grained and dark-coloured.——BRITISH BAY SALT, CHESHIRE LARGE-GRAINED S.; by evaporating native brine at a heat of 130° to 140° Fahr.; hard cubical crystals. Both of the above are used to salt provisions for hot climates, as they dissolve very slowly in the brine as it grows weaker. CHESHIRE STOVED SALT, LUMP S., BASKET S.; obtained by evaporating the brine of salt springs; small flaky crystals.——LONDON’S PATENT SOLID SALT; Cheshire rock salt, melted and ladled into moulds.——ROCK SALT, FOSSIL S.; SAL GEMMÆ, SAL FOSSILIS; found in mineral beds in Cheshire; has commonly a reddish colour; chiefly exported for purification.

_Prop._ Pure chloride of sodium is fixed in the air; crystallises in anhydrous cubes, which are often grouped into pyramids or steps; dissolves in about 2-1/2 parts of water at 60° Fahr.; its solubility is not increased by heat; it is slightly soluble in proof spirit; insoluble in alcohol; decrepitates when heated; fuses at a red heat, and volatilises at a much higher temperature.

_Pur., &c._ The common salt of commerce contains small portions of chloride of magnesium, chloride of calcium, and sulphate of calcium; and hence has commonly a slightly bitter taste, and deliquesces in the air. To separate these, dissolve the salt in 4 times its weight of pure water, and drop into the filtered solution, first, chloride of barium, and then carbonate of sodium, as long as any precipitate falls; filter, and evaporate the clear fluid very slowly, until the last crystallises, which is pure chloride of sodium. (‘Thomson’s Chem.,’ ii, 377.) For medical purposes the Ph. E. orders the salt to be dissolved in boiling water, and the solution to be filtered and evaporated over the fire, skimming off the crystals as they form, which must then be quickly washed in cold water, and dried. A solution of pure salt is not precipitated by a solution of carbonate of ammonium, followed by a solution of phosphate of sodium; a solution of 9 gr. in distilled water is not entirely precipitated by a solution of 26 gr. of nitrate of silver. (Ph. E.)

_Uses._ Common salt is stimulant, antiseptic, and vermifuge, and is hence employed as a condiment, and for preserving animal and vegetable substances. It is also occasionally used in medicine, in clysters and lotions.

=Sodium, Dried Sulphate of.= _Syn._ SODÆ SULPHAS EXSICCATA, EFFLORESCED GLAUBER SALT. Expose the crystals to a warm dry air till they fall into powder. They lose half their weight. The dose is reduced in like proportion.

=Sodium, Effervescing Citro-tartrate of.= _Syn._ SODÆ CITRO-TARTRAS EFFERVESCENS. (B. P.) _Prep._ Mix thoroughly, powdered bicarbonate of soda, 17 oz.; tartaric acid, 8 oz.; and citric acid, 6 oz.; place in a dish or pan of suitable form, heated to between 200° and 220° Fahr., and when the particles begin to aggregate, stir assiduously till they assume a granular form. By means of suitable sieves separate the granules of uniform and most convenient size. Preserve in well-closed bottles.

=Sodium, Ethylate.= Prepared as POTASSIUM ETHYLATE, substituting sodium for potassium. Properties similar to ethylate of potassium.

=Sodium, Hydrate of.= NaHO. _Syn._ HYDRATE OF SODA, SODIUM HYDRATE, CAUSTIC SODA; SODÆ HYDRAS. _Prep._ Exactly in the same manner from carbonate of sodium as potassium hydrate is prepared from carbonate of potassium.

The ‘Pharmaceutical Journal’[177] states that a pure hydrate of sodium is now manufactured from metallic sodium by the following method:——A deep silver vessel, of a hemispherical form, and capable of holding about four gallons of water, is employed. Into this vessel, which is cooled externally with a current of cold water, is placed a very little water, and upon the water is placed a cube of metallic sodium, of about half an inch in diameter.

[Footnote 177: 3rd series, i, 65.]

The vessel is made to revolve, so as continually to bring fresh portions of liquid into contact with the metal, and by this means explosion is avoided. When the first cube of metal has dissolved, and yielded a thick syrupy liquid, a little more water and a second cube of metal are added, and the reaction allowed to take place, as before, the vessel being kept in motion all the time. In this manner several pounds of sodium may be worked up into soda.

The thick syrup so resulting is next evaporated down, heated to redness, fused, and poured into a mould.

Inasmuch as the price of sodium is five shillings a pound, the yield of soda from 1 lb. of metal being about 1-3/4 lb., it is plain that the alkali so prepared must be cheap.

The danger of explosions (which, however, are not likely to occur if proper care is taken) necessitates the employment of skilled labour in this manufacture, and constitutes a very serious drawback to the commercial success of the process.

Greyish, semitranslucent, deliquescent masses, very soluble in water, and bearing a very great resemblance to the corresponding potassium compound.

=Sodium, Hypochlo′′rite of.= _Syn._ CHLORINATED SODA, CHLORIDE OF SODA‡; SODA CHLORINATA, L. _Prep._ (Dr Christison.) Dried carbonate of sodium, 19 parts, are triturated with water, 1 part, and the mixture placed in a proper vessel, and exposed to the prolonged action of chlorine gas, generated from a mixture of chloride of sodium, 10 parts; binoxide of manganese, 8 parts; sulphuric acid, 14 parts; (diluted with) water, 10 parts.

=Sodium Hypophosphate.= See PHOSPHORUS.

=Sodium, Hyposul′phite of.= Na_{2}S_{2}O_{3}. _Syn._ SODÆ HYPOSULPHIS, L. _Prep._ 1. Dried carbonate of sodium, 1 lb.; flower of sulphur, 10 oz.; mix, and slowly heat the powder in a porcelain dish until the sulphur melts; stir the fused mass freely to expose it to the atmosphere until the incandescence flags, then dissolve the mass in water, and immediately boil the filtered liquid with some flowers of sulphur; lastly, carefully concentrate the solution for crystals.

2. A stream of well-washed sulphurous anhydride gas is passed into a strong solution of carbonate of sodium, which is then digested with sulphur at a gentle heat during several days; by evaporating the solution at a moderate temperature, the salt is obtained in large and regular crystals.

3. (Capaun’s process.) Boil a dilute solution of caustic soda with sulphur to saturation, then pass sulphurous acid gas into the solution until a small portion, when filtered, is found to have a very pale yellow colour; when this is the case, it must be filtered and evaporated, as before.

4. (P. Cod.) Dissolve carbonate of sodium, 8 parts, in water, 16 parts; add of sublimed sulphur, 1 part, and pass sulphurous acid gas, in excess, into the solution; next boil the liquid in a glass matrass for a few minutes, filter, gently evaporate the filtrate to 1-3rd its volume, and set it aside in a cool place to crystallise.

_Prop., &c._ Hyposulphite of sodium crystallises in four-sided prisms, which, in the dry state, are unalterable in the air; it is freely soluble in water. It may be perfectly freed from sulphide of sodium by agitating it with about half its weight of alcohol; the alcohol dissolves out the sulphide, which may then be easily separated. This salt is now very extensively used in the practice of photography, also as an ‘antichlore,’ to extract the last traces from paper pulp.

=Sodium, Iodide of.= NaI. _Syn._ SODII IODIDUM. _Prep._ As IODIDE OF POTASSIUM. This, as well as the bromide, crystallises in clear or whitish cubes, deliquescent, and soluble in water. Used in medicine in the same manner as the corresponding potassium salts.

=Sodium and Iron, Pyrophosphate of.= _Syn._ SODÆ ET FERRI PYROPHOSPHAS, NATRUM PYROPHOSPHORICUM FERRATUM. (Ph. G.) _Prep._ Dissolve 20 oz. of pyrophosphate of soda in 40 oz. of cold distilled water, and add, gradually, to the solution, and with constant stirring, 8 oz. (by weight) of solution of perchloride of iron (Ph. G.), previously diluted with 22 oz. of distilled water, as long as the precipitate is redissolved. Filter, and to the clear, bright green liquid thus obtained pour in 100 oz. (by weight) of rectified spirit, wash the precipitate with more spirit, press it between blotting paper, and dry by a gentle heat.

=Sodium Lactate.= _Syn._ SODII LACTAS. _Prep._ Let lactate acid be diluted with three parts of water; saturate whilst boiling with sodium bicarbonate; then evaporate, and run into flakes.

Sodium lactate is a very deliquescent salt. The solution evaporated to the consistence of a syrup deposits flattened prismatic crystals, and stellar groups of needles.

=Sodium, Ni′trate of.= NaNO_{3}. _Syn._ CHILI SALTPETRE, CUBIC NITRE; SODÆ NITRAS, L. This salt occurs native like ordinary nitre, and is chiefly imported into England from South America. It is largely employed as a manure, in the preparation of nitric acid, and, recently, in the manufacture of fireworks, on account of the comparative slowness with which it burns. It is deliquescent and very soluble in water.

=Sodium, Nitrite of.= _Syn._ SODÆ NITRIS. (B. P., 1864.) Mix nitrate of soda, 1 lb., and charcoal, recently burned, and in fine powder, 1-1/4 oz., thoroughly in a mortar, and drop the mixture in successive portions into a clay crucible, heated to a dull redness. When the salt has become quite white, raise the heat so as to liquefy it, pour on to a clean flagstone, and when it has solidified break into fragments, and keep in a stoppered bottle.

=Sodium, Oxide of.= Na_{2}O. _Syn._ ANHYDROUS SODA. _Prep._ By burning dry metallic sodium in air. White powder, very deliquescent, and soluble in water, forming pure sodium hydrate.

=Sodium, Phos′phate of.= Na_{2}PO_{4}.12Aq. _Syn._ COMMON TRIBASIC PHOSPHATE OF SODA, RHOMBIC P. OF S.; SODÆ PHOSPHAS (B. P., Ph. L., E., & D.). _Prep._ 1. (Ph. E.) Take of powdered bone ashes, 10 lbs.; sulphuric acid, 44 fl. oz.; mix, add gradually of water 6 pints, and digest for 3 days, replacing the water which evaporates; then add 6 pints of boiling water, strain through linen, and wash the residue on the filter with boiling water; mix the liquors, and, after defecation, decant and evaporate to 6 pints; let the impurities again settle, and neutralise the clear fluid, heated to boiling, with a solution of carbonate of sodium in slight excess; crystals will be deposited as the solution cools, and by successively evaporating, adding a little more carbonate of sodium to the mother liquor till it is feebly alkaline, and cooling, more crystals may be obtained; these must be kept in close vessels. The formula of the Ph. D. is nearly similar. It is placed in the Materia Medica of the B. P. and Ph. L.

2. (Funcke.) To ground calcined bones, diffused through water, add a little dilute sulphuric acid to saturate any carbonate of calcium present; when effervescence ceases, dissolve the whole in nitric acid, q. s.; to this solution add as much sulphate of sodium as the bone ash used, and distil the whole to recover the nitric acid; the residuum is treated with water, and the resulting solution filtered, evaporated, and crystallised.

_Prop., &c._ It forms very beautiful oblique rhombic prisms, of the formula Na_{2}H,PO_{4},12H_{2}O, which effloresce in the air, dissolve in about 4 parts of cold water and in 2 parts at 212° Fahr., and fuse when heated. As a medicine it is mildly aperient, in doses of 1/2 to 1 oz., or even more; and antacid in doses of 20 to 30 gr., frequently repeated. It has a purely saline taste, resembling that of culinary salt, and is commonly taken in broth or soup.

=Sodium Pyrophosphate (Crystallised).= _Syn._ SODÆ PYROPHOSPHAS CRYSTALLISATA. (P. Cod.) _Prep._ This salt may be obtained by heating, gently at first, and afterwards to a red heat, crystallised phosphate of sodium in a platinum crucible until all the water is driven off, and the salt has become fused. Dissolve the fused mass in water, filter, and concentrate until it has a density of 1·20, and crystallise in the cold.

=Sodium, Salicylate of.= _Syn._ SODÆ SALICYLUS. _Prep._ Made by neutralising a solution of pure salicylic acid with caustic soda, and evaporating to dryness. It must be purified by crystallisation from alcohol. Antipyretic; given in acute rheumatism.——_Dose_, 10 to 20 grams.

=Sodium Santonate.= _Syn._ SODÆ SANTONAS. This salt is made by digesting an alcoholic solution of santonic acid with carbonate of soda, evaporating, redissolving in strong alcohol, and crystallising.

=Sodium, Sesquicarbonate of.= Na_{4}H_{2}(CO_{3})_{3}. A salt found native on the banks of the soda lakes of Sotrena, in Africa, whence it is exported as ‘Trona.’

=Sodium Silicate.= See GLASS, SOLUBLE.

=Sodium, Stan′nate of.= Na_{2}SnO_{3}. _Prep._ (Greenwood & Co.) Caustic soda, 22 lbs., is heated to low redness in an iron crucible, when nitrate of sodium, 8 lbs., and common salt, 4 lbs., are added; when the mixture is at a ‘fluxing heat,’ 10 lbs. of feathered block tin is stirred in with an iron rod, both the stirring and heat being continued until the mass becomes red hot and ‘pasty,’ and ammoniacal fumes are given off. The product may be purified by solution and crystallisation. Patented. (See _below_.)

=Sodium, Stan′nite of.= _Prep._ (Greenwood & Co.) From caustic soda, 13-1/2 lbs.; feathered block tin and common salt, of each 4 lbs.; as the last. Patented. Both the above are used to prepare tin mordants (about 12 oz. to water, 1 gall.). The stannate and stannite of potassium are prepared in a similar manner.

=Sodium Sulphate.= _Syn._ SODÆ SULPHIS. _Prep._ Pass sulphurous acid to saturation through a solution of carbonate of soda. Used internally for sarcina ventriculi, and externally as an application in skin diseases of fungous origin. Hyposulphate of soda is employed in the same cases.

=Sodium, Sul′phate of.= Na_{2}SO_{4}.10Aq. _Syn._ GLAUBER’S SALT; SODÆ SULPHAS (B. P., Ph. L., E., & D.), SAL CATHARTICUS GLAUBERI†, L. This is obtained as a secondary product in various chemical processes; but it may be easily formed directly from its constituents.

_Prop., &c._ It forms transparent, six-sided, irregular, channelled prisms, with dihedral summits, of the formulae Na_{2}SO_{4}10H_{2}O, which effloresce in the air, and fall to an opaque white powder; soluble in about 3 parts of water at 60°, and in considerably less at 100° Fahr., but at a higher temperature its solubility rapidly lessens; insoluble in alcohol; fuses when heated. It is seldom wilfully adulterated. When pure the solution is neutral to test paper; nitrate of silver throws down scarcely anything from a dilute solution; nitrate of baryta more, which is not dissolved by nitric acid. It loses 55·5% of its weight by a strong heat.