Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 244

Since the introduction of the above, the consumption of nitrate of soda is sometimes lessened by more than half.

Another very recent improvement, the invention of a German chemist named Sprengel, is the subst.i.tution of water spray, blown in by steam, for steam jets, in the leaden chambers. By this method a saving of coal to the extent of one third is said to be effected.

In theory, 1 molecule of sulphur requires only 3 molecules of oxygen to convert it into sulphuric acid, viz. 2 to form sulphurous anhydride, and 1 to convert the latter into sulphuric anhydride, which combines with 1 molecule of water to form the acid. Thus, 1 kilogram of sulphur requires 1500 grams or 1055 litres of oxygen, which is equivalent to 5275 litres of air containing 4220 litres of nitrogen; when pyrites is used, a far larger quant.i.ty of air is required, for the obvious reason that the pyrites becomes converted into ferric peroxide. 1 kilogram of pyrites requires for its combustion nearly 6600 litres of air.

In well-regulated works the spent and escaping gases should not contain more than 2 per cent. of oxygen. If from 100 kilograms of sulphur 306 kilograms of strong acid of sp. gr. 184 be obtained, the result is regarded as very satisfactory; more frequently the product from 100 kilograms of sulphur does not exceed 280 or 290 kilograms.

_Purif._ Commercial sulphuric acid frequently contains nitrous acid and other oxides of nitrogen, a.r.s.enic, lead, and saline matter. The nitrous acid may be removed by adding a little sulphate of ammonia, and heating the acid to ebullition for a few minutes. Both nitric and nitrous acid are thus entirely decomposed into water and nitrogen gas. The a.r.s.enic may be got rid of by adding a little sulphide of barium to the acid, agitating the mixture well, and, after repose, decanting and distilling it. Lead, which exists as sulphate, may be separated as a white precipitate by simply diluting the acid with water. Saline matter may be removed by simple rectification. A good way of purifying oil of vitriol is to heat it nearly to the boiling point, and pa.s.s a current of hydrochloric acid through it; the a.r.s.enic is thus carried over as the volatile chloride of a.r.s.enic, while the nitrous and nitric acids are expelled almost completely. To obtain a perfectly pure acid, it should be distilled after the removal of the nitrous acid and a.r.s.enic by the methods indicated above. "The distillation is most conveniently conducted, on the small scale, in a gla.s.s retort, containing a few platinum chips, and heated by a sand bath or gas-flame, rejecting the first 1/2 fl. oz. that comes over."

(Ph. E.) In the Ph. D. the first tenth of the distillate is ordered to be rejected, and the process to be stopped when no more than about 1 fl. oz.

is left in the retort.

According to Dr Ure, the capacity of the retort should be from 4 to 8 times as great as the volume of the acid, and connected with a large tubular receiver by a loosely fitting gla.s.s tube, 4 feet long and 1 to 2 inches in diameter. "The receiver should not be surrounded with cold water." We find that fragments of gla.s.s, or of rock crystals, may be advantageously subst.i.tuted for platinum foil, to lessen the explosive violence of the ebullition. Sulphuric acid which has become brown by exposure may be decolorised by heating it gently, the carbon of the organic substances being thus converted into carbonic acid.

_Prop._ Commercial sulphuric acid (oil of vitriol) is a colourless, odourless, and highly corrosive liquid, the general properties of which are well known. Its sp. gr. at 60 should never be greater than 1848, or less than 1840. (Miller and Odling give the sp. gr. of the pure and concentrated acid as 1842; Abel and Bloxam, as 1848; Apjohn gives it as 1846, and Hardwich about 1845.) It is immediately coloured by contact with organic matter. It attracts water so rapidly from the atmosphere when freely exposed to it, as to absorb 1-3rd of its weight in 24 hours, and 6 times its weight in a few months. When 3 volumes are suddenly mixed with 2 of water, the temperature of the mixture rises more than 180 Fahr. Its freezing point appears to be about 60 below that of water (Miller and Odling give that of the rectified acid as -30 Fahr.; Apjohn and Abel and Bloxam, -29). It boils at about 620 Fahr. (6206, Odling; 620, Hardwich and Fownes; 617, Apjohn; 5906, Abel and Bloxam). It exhibits all the properties of the acids in an exalted degree. Its salts are called sulphates.

In the following table is given the quant.i.ty of anhydrous sulphuric acid contained in sulphuric acid at 60F. (155C.).

+--------------------------------+----------------------------------+ Hydrated Sp. Gr. Anhydrous Hydrated Sp. Gr. Anhydrous Sulphuric Acid. Sulphuric Acid. Acid. Acid. 100 18485 8154 76 16630 6197 99 18475 8072 75 16520 6115 98 18460 7990 74 16415 6034 97 18439 7909 73 16321 5955 96 18410 7828 72 16204 5871 95 18376 7740 71 16090 5789 94 18336 7665 70 15975 5708 93 18290 7583 69 15868 5626 92 18233 7502 68 15760 5545 91 18179 7420 67 15648 5463 90 18115 7339 66 15503 5382 89 18043 7257 65 15390 5300 88 17962 7175 64 15280 5218 87 17870 7094 63 15170 5137 86 17774 7012 62 15066 5055 85 17673 6931 61 14960 4974 84 17570 6849 60 14860 4892 83 17465 6768 59 14760 4811 82 17360 6686 58 14660 4729 81 17245 6605 57 14560 4658 80 17120 6523 56 14460 4568 79 16993 6442 55 14360 4485 78 16870 6360 54 14265 4503 77 16750 6278 53 14170 4322 +--------------------------------+----------------------------------+

_Pur._ "Free from colour and odour. Sp. gr. 1843. 100 gr. are saturated by 285 gr. of crystallised carbonate of soda." (Ph. L.) "What remains after the acid is distilled to dryness does not exceed 1/400th part of its weight. Diluted sulphuric acid is not discoloured by sulphuretted hydrogen." (Ph. L. 1836.) "Diluted with its own volume of water, only a scanty muddiness arises, and no orange fumes escape. Sp. gr. 1840." (Ph.

E.) "The rectified acid (ACIDUM SULPHURIc.u.m PURUM--Ph. E. & D.) is colourless; dilution causes no muddiness; solution of sulphate of iron shows no reddening at the line of contact when poured over it. Sp. gr.

1845." (Ph. E.) Sp. gr. 1846--Ph. D.; 1843--B. P.; 1842--Ure.

_Tests._--See SULPHATE.

_Uses, &c._ "The uses of sulphuric acid are so numerous that it would be impossible to mention all of them, sulphuric acid being to chemical industry what iron is to the mechanical. Sulphuric acid is employed in preparing a great many other acids--among them, nitric, hydrochloric, sulphurous, carbonic, tartaric, citric, phosphoric, stearic, oleic, and palmitic. Further, sulphuric acid is used in making superphosphates, soda, sulphate of ammonia, alum, sulphates of copper and iron, in paraffin and petroleum refining, silver refining, manufacture of garacine, garanceux, and other madder preparations, manufacture of glucose from starch, to dissolve indigo, &c.[216] In the diluted state it is used in medicine.

When swallowed, it acts as a violent corrosive poison. The antidotes are chalk, whiting, magnesia, carbonate of soda, or carbonate of potash, mixed with water, or any bland diluent, and taken freely, an emetic being also administered.

[Footnote 216: Wagner.]

_Estim._ The strength of sulphuric acid is most correctly ascertained by its power of saturating bases. In commerce, it is usually determined from its sp. gr. The quant.i.ty of sulphuric acid present in a compound may be determined by weighing it under the form of sulphate, as explained in a former part of this volume. See ACIDIMETRY.

_Concluding Remarks._ According to most of our standard works on chemistry, British oil of vitriol, when purified and brought to its maximum strength by distillation, is a definite chemical compound, having the formula H_{2}SO_{4}, and designated normal sulphuric acid by Odling.

Marignac, however, a.s.serts that the distilled acid always contains an excess of water, and that the true monohydrate can only be obtained by submitting fuming sulphuric acid ('Nordhausen s. a,') to congelation.

According to this chemist, the true monohydrate readily freezes in cold weather, and remains solid up to 51 Fahr. Two other definite hydrates of sulphuric acid are generally recognised by chemists, viz.--Bihydrated sulphuric acid ('glacial s. a,'), having a sp. gr. of 178; freezing at about 40 Fahr. (47, Miller); and boiling at about 435 (Apjohn; 401 to 410, Odling): Terhydrated sulphuric acid, having a sp. gr. of 1632, and the boiling-point 348 Fahr. See also SULPHURIC ACID, NORDHAUSEN (_below_).

=Sulphuric Acid, Al'coholised.= _Syn._ ACIDUM SULPHURIc.u.m ALCOHOLISATUM, L.; EAU DE RABEL, Fr. _Prep._ (P. Cod.) To rectified spirit, 3 parts, add, very gradually, sulphuric acid, 1 part. It is generally coloured by letting it stand over a little cochineal. Refrigerent, and, externally, escharotic.--_Dose_, 1/2 fl. dr. to water, 1 pint; as a cooling drink in fevers, &c.

=Sulphuric Acid, Anhy'drous.= SO_{3}. _Syn._ SULPHURIC ANHYDRIDE, DRY SULPHURIC ACID; ACIDUM SULPHURIc.u.m SINE AQUa, L. _Prep._ 1. By heating Nordhausen acid to about 100 Fahr. in a gla.s.s retort connected with a well-cooled receiver.

2. By distilling anhydrous bisulphate of soda, which has previously been raised to a low red heat in an earthen retort, to which a receiver is fitted without the aid of corks.

3. (Barreswill.) 2 parts of the strongest oil of vitriol are gradually added to 3 parts of anhydrous phosphoric acid, contained in a retort surrounded by a freezing mixture; when the compound has a.s.sumed a brown colour, the retort is removed from the bath, and connected with a receiver which is set there in its place; a gentle heat is now applied to it, when white vapours pa.s.s over into the receiver, and condense there under the form of beautiful silky crystals. The product equals in weight that of the phosphorus originally employed. "If a few drops of water be added, a dangerous explosion ensues."

_Prop._ White, silky, asbestos-like crystals, deliquescing rapidly, and fuming in the air; put into water, it hisses like a red-hot iron; it melts at 77, and rapidly volatilises at 86 Fahr.; it does not redden dry litmus paper; sp. gr. 197 at 78 Fahr.

=Sulphuric Acid, Aromat'ic.= _Syn._ ELIXIR OF VITRIOL, ACID E. OF V.; ACIDUM SULPHURIc.u.m AROMATIc.u.m (B. P., Ph. E. & D.), L. _Prep._ 1. (Ph. E.

& D.) Oil of vitriol, 3-1/2 fl. oz.; rectified spirit, 1-1/2 pint; mix, add of powdered cinnamon, 1-1/2 oz.; powdered ginger, 1 oz.; digest for 6 days (7 days--Ph. D.), and filter. Sp. gr. 974--Ph. D.

2. (Wholesale.) From compound tincture of cinnamon, 1 gall.; oil of vitriol, 1 lb.; mix, and in a week filter--_Dose_, 10 to 30 drops, in the same case as the dilute acid.

3. (B. P.) Sulphuric acid, 3; rectified spirit, 40; cinnamon, in powder, 2; ginger, in powder, 1-1/4; mix the acid gradually with the spirit, add the powders, macerate for 7 days, and filter.--_Dose_, 5 to 30 minims.

=Sulphuric Acid, Dilute'.= _Syn._ SPIRIT OF VITRIOL; ACIDUM SULPHURIc.u.m DILUTUM (B. P., Ph. L., E., & D.), L. _Prep._ 1. (Ph. L.) Take of sulphuric acid, 15 fl. dr., and dilute it gradually with distilled water, q. s. to make the whole exactly measure a pint. Sp. gr. 1103. "1 fl. oz.

of this acid is exactly saturated by 216 gr. of crystallised carbonate of soda."

2. (Ph. E.) Sulphuric acid, 1 fl. oz.; water, 13 fl. oz. Sp. gr. 1090.

3. (Ph. D.) Pure sulphuric acid, 1 fl. oz.; distilled water, 13 oz. Sp.

gr. 1084.

4. (B. P.) Sulphuric acid, 3; distilled water, q. s. to measure 35-3/4; mix by adding the acid gradually to the water.--_Dose_, 4 to 20 minims.

_Prop., &c._ Antiseptic, tonic, and refrigerant.--_Dose_, 10 to 30 drops, largely diluted with water, several times daily; in low typhoid fevers, pa.s.sive haemorrhages, profuse perspiration, in various skin diseases to relieve the itching, in dyspepsia, &c. It is also used externally.

=Sulphuric Acid, Nordhausen.= _Syn._ FUMING SULPHURIC ACID; ACIDUM SULPHURIc.u.m FUMANS, L. _Prep._ By distilling calcined ferrous sulphate ('green vitriol') in earthen retorts. The retorts, which are shown at A in the plate after the 'green vitriol' has been put into them, are placed in a galley-furnace, as shown below, the necks pa.s.sing through the wall of the furnace, and being properly secured to the necks of the receivers (B B.). Into each of the flasks 2-1/2 lbs. of green vitriol are put; on the first application of heat only sulphurous acid and weak hydrated sulphuric acid come over, and are usually allowed to escape, the receivers not being securely luted until white vapours of anhydrous sulphuric acid are seen.

Into each of the receiving flasks 30 grams of water are poured, and the distillation continued for 24 to 36 hours. The retort flasks are then again filled with raw material, and the operation repeated four times before the oil of vitriol is deemed strong enough. The residue in the retorts is red (peroxide) of iron, still retaining some sulphuric acid.

The product is a brown oily liquid, which fumes in the air, is intensely corrosive, and has a sp. gr. about 1900. When heated to about 100 Fahr.

the anhydrous acid is given off, and ordinary oil of vitriol is left.

According to Marignac, crystals of normal sulphuric acid (H_{2}SO_{4}) are formed in this acid when it is submitted to a low temperature. Nordhausen acid is so called from the place of its manufacture in Saxony. It may be regarded as a mixture or compound of H_{2}SO_{4} and SO_{2}. It is chiefly used for dissolving indigo.

[Ill.u.s.tration]

=SULPHURIC ANHYDRIDE.= See SULPHURIC ACID, ANHYDROUS.

=SULPHURIC E'THER.= See ETHER.

=SUL'PHUROUS ACID.= SO_{2}. _Syn._ SULPHURUS ANHYDRIDE; ACIDUM SULPHUROSUM, B. P. This compound is freely evolved in the gaseous form when sulphur is burnt in air or oxygen, and when the metals are digested in hot sulphuric acid; and, mixed with carbonic acid, when charcoal, chips of wood, cork, and sawdust, are treated in the same way.

_Prep._ 1. By heating together sulphur and strong sulphuric acid.

2. By the action of sulphuric acid on chippings of copper or mercury at a gentle heat. Pure.

3. (Berthier.) By heating, in a gla.s.s retort, a mixture of black oxide of manganese, 100 parts, and sulphur, 12 or 14 parts. Pure. The gas evolved should be collected over mercury, or received into water.

4. (Redwood.) Pounded charcoal, 1/2 oz.; oil of vitriol, 4 fl. oz.; mix in a retort, apply the heat of a spirit lamp, and conduct the evolved gases by means of a bent tube into a bottle containing water. The sulphurous acid is absorbed, whilst the carbonic acid gas pa.s.ses off.

5. (B. P.) Distilled water, saturated with sulphurous anhydride. It is colourless and emits a pungent odour. Used as a deoxidiser, disinfectant, and antiseptic. Diluted with from 1 to 2 parts of water it is employed as a lotion for wounds, cuts, ulcers, bed-sores, scalds, and burns; with from 1 to 5 of water it is used as a gargle, also as a lotion in parasitic skin diseases; from 1/2 to 1 dr., in a wine-gla.s.sful of water, 3 times a day, relieves constant sickness.

_Prop., &c._ Water absorbs 30 times its volume of this gas. Pure liquid sulphurous acid can only be obtained by pa.s.sing the pure dry gas through a gla.s.s tube surrounded by a powerful freezing mixture. Its sp. gr. is 145; boiling point, 14 Fahr.; it causes intense cold by its evaporation.

Sulphurous acid forms salts called sulphites.

_Uses._ To bleach silks, woollens, straw, &c., and to remove vegetable stains and iron-moulds from linen. For these purposes it is prepared from sawdust or any other refuse carbonaceous matter.

Several preparations containing sulphurous acid have recently been invented by the Editor and introduced to the public as agents in sanitation under the name of _Sporokton_ (germ-killer). To understand the nature and merits of these preparations it is desirable to explain the true and individual meanings of 'Deodoriser,' 'Antiseptic,' and 'Disinfectant,'--words which are too often improperly employed as if they had the same signification, and as if, in fact, they were convertible terms.

A deodoriser is a substance which will absorb or destroy bad smells; an antiseptic is an agent which will prevent or r.e.t.a.r.d putrefaction; and a disinfectant is an agent which will render harmless the virus of smallpox, scarlet fever, measles, diphtheria, influenza, pleuro-pneumonia, cattle plague, glanders, distemper in dogs, and other infectious or contagious diseases.

Now, medical authorities and sanitarians are of opinion that the most potent disinfectant with which we are acquainted is sulphurous acid, a gas which has been used for ages, as a fumigator. Sulphurous acid has not, however, been so generally employed for disinfecting purposes as one might from these circ.u.mstances have expected, on account of the difficulties and inconveniences which formerly attended its generation.