Chapter LXXI: Part 2 (32)

Some few years back Messrs Dubrunfaut and Péligot being cognisant of the fact of the insolubility, in boiling water, of the compounds of sugar with lime, based upon it a method of separating crystallisable sugar from treacle. Péligot has obtained from common treacle one fourth of its weight of crystallised sugar, by dissolving the precipitated sugar lime in water, and separating the lime by passing into the mixture a stream of carbonic acid.

Sugar may be obtained from nearly all sweet vegetable substances, by a process essentially similar to that described above.

_Table showing the Specific Weight of Sugar Solutions
with the corresponding percentage of Cane Sugar at
17·5° C._——GERLACH.

------------------------+-------------------------+----------------------
Percentage, Specific |Percentage, Specific |Percentage, Specific
Cane Sugar. Weight |Cane Sugar. Weight |Cane Sugar. Weight
of Sol. | of Sol. | of Sol.
| |
75 1·383,342 | 49 1·227,241 | 24 1·101,377
74 1·376,822 | 48 1·221,771 | 23 1·096,792
73 1·370,345 | 47 1·216,339 | 22 1·092,240
72 1·363,910 | 46 1·210,945 | 21 1·087,721
71 1·357,518 | 45 1·205,589 | 20 1·083,234
70 1·351,168 | 44 1·200,269 | 19 1·078,779
69 1·344,860 | 43 1·194,986 | 18 1·074,356
68 1·338,594 | 42 1·189,740 | 17 1·069,965
67 1·332,370 | 41 1·184,531 | 16 1·065,606
66 1·326,188 | 40 1·179,358 | 15 1·061,278
65 1·320,046 | 39 1·174,221 | 14 1·056,982
64 1·313,946 | 38 1·169,121 | 13 1·052,716
63 1·307,887 | 37 1·164,056 | 12 1·048,482
62 1·301,868 | 36 1·159,026 | 11 1·044,278
61 1·295,890 | 35 1·154,032 | 10 1·040,104
60 1·289,952 | 34 1·149,073 | 9 1·035,961
59 1·284,054 | 33 1·144,150 | 8 1·031,848
58 1·278,197 | 32 1·139,261 | 7 1·027,764
57 1·272,379 | 31 1·134,406 | 6 1·023,710
56 1·266,600 | 30 1·129,586 | 5 1·019,686
55 1·260,861 | 29 1·124,800 | 4 1·015,691
54 1·255,161 | 28 1·120,048 | 3 1·011,725
53 1·249,500 | 27 1·115,330 | 2 1·007,788
52 1·243,877 | 26 1·110,646 | 1 1·003,880
51 1·238,293 | 25 1·105,995 | 0 1·000,000
50 1·232,748 | |
------------------------+-------------------------+----------------------

=Sugar, Al′um.= _Syn._ SACCHARUM ALUMINATUM, ALUMEN SACCHARINUM, L. From alum and white sugar, in fine powder, equal parts, formed into minute sugar-loaf shaped lumps with mucilage of gum Arabic made with rose water. Used to make astringent lotions and eye-waters.

=Sugar. Bar′ley.= _Syn._ SACCHARUM HORDEATUM, PENIDIUM, SACCHARUM PENIDIUM, L. _Prep._ Take of saffron, 12 gr.; hot water, q. s.; sugar, 1 lb.; boil to a full ‘candy height,’ or that state called ‘crack,’ or ‘crackled sugar,’ when 2 or 3 drops of clear lemon juice or white vinegar must be added, and the pan removed from the fire and set for a single minute in cold water, to prevent its burning; the sugar must be then at once poured out on an oiled marble slab, and either cut into pieces or rolled into cylinders and twisted in the usual manner. One drop of oil of citron, orange, or lemon, will flavour a considerable quantity. White barley sugar is made with a strained decoction of barley instead of water, or starch is added to whiten it.

=Sugar, Beet-root.= _Syn._ SACCHARUM BETÆ, L. Sugar obtained from the white beet.

In the following table the names of the countries in which this plant is cultivated are given, together with the amount of sugar annually produced in each:

France 280,000 tons.[207]
Germany 260,000 ”
Austria and Hungary 180,000 ”
Russia and Poland 130,000 ”
Belgium 50,000 ”
Holland and other countries 17,000 ”

[Footnote 207: British Manufacturing Industries, Glanford.]

The white beet is used in preference to the red varieties, not only because of the colour of its juice, but also in consequence of its being richer in sugar. The roots vary in their yield of sugar according to quality and the season of the year. They are generally in best condition in October. The root is made up of a series of small cells, which are filled with the saccharine fluid. According to Wagner the constituents of the sugar-beet are as follows:

Water 82·7
Sugar 11·3
Cellulose 0·8
Albumen, casein, and other bodies 1·5
Fatty matter 0·1
Organic substances, citric acid, pectin, and pectic acid. Asparagin, }
aspartic acid, and betain, a substance having, according to }
Schiebler, the formula C_{15}H_{33}N_{3}O_{6} }
Organic salts, oxalate and pectate of calcium, oxalate and pectate }
of potassium and sodium } 3·7
Inorganic salts, nitrate and sulphate of potash, phosphate of lime }
and magnesia }
Twelve and a half hundred weight of beet yield on an average 1 cwt.
of raw sugar, or 8 per cent.

The first operation in the manufacture of beet-root sugar after washing and cleansing the roots (an operation which sometimes reduces their weight 10 or 20 per cent.) is the extraction from them of the juice. This may be effected either by:

1. Pressure.
2. Centrifugal power.
3. Dialysis.

1. _Pressure._ The roots being put into a proper crushing machine are soon reduced to an uniform pulp, which in some manufactories is subjected to pressure wrapped in linen cloths under stone or iron rollers, and in others is placed in bags and placed under the Bramah or hydraulic press, the resulting juice being collected in proper receptacles.

2. _Centrifugal power._ This method is that generally employed for separating the juice from the pulp, which thus yields between 50 or 60 per cent. of juice. A weak saccharine solution, also used in sugar manufacture, is afterwards obtained by mixing the residue of the pulp with water, and subjecting it to the same process.

3. _Dialysis._ The application of the principle of diffusion for the extraction of the sugar from the beet-root originated with M. Robert. The fresh roots, cut into thin slices, are immersed in a little more than their own weight of water heated to about 120° F. The crystalloid sugar thus diffuses out through the cell membrane which encloses it into the surrounding water, leaving the pectous and colloid matters, such as albumen, gum, &c., behind. The operation which is so managed as to bring the same water into contact with successive quantities of root, yields a saccharine solution of nearly the same strength as the natural juice. The solution so obtained is, after concentration and the usual methods, converted into sugar. The same process is said to have been tried with cane sugar, and with equally satisfactory results.

The succeeding stages of the manufacture of beet sugar, such as refining, liming, decolorising, &c., are the same as those already described under cane sugar.

Beet sugar is in every respect identical with cane. It was discovered in 1747 by Marggraf, of Berlin, but it did not come into use until about the beginning of the present century, its manufacture at this period in France being necessitated by an edict of the first Napoleon’s, which prohibited the importation of cane sugar into that country.

The engraving represents a vacuum pan much used in the French sugar refineries.

Fig. 1 gives a perspective, and fig. 2 a sectional view of this evaporating pan.

The boiling-pan (B) consists of two air-tight hemispheres, surmounted by a funnel, connected by the tube (_l_) with the condenser (A). The apparatus is supplied by steam by (_r s_), the steam circulating in the boiling-pan by means of the pipes (_g_), fig. 2. By opening the lever valves (_f_) the juice can be run by means of the pipe (_o_) into the pan (_p_). When the pan, after continued boiling, requires to be refitted, the pipes (_l_ and _w_) are connected to an air-pump. The manometer (_h_) shows the state of the air pressure, which can be regulated by opening the pipes connected to the vacuum chamber. By means of the gauge cylinder (G) the quantity of syrup in the boiling-pan can be ascertained, the gauge cylinder being connected to the boiling-pan by the pipes (_a_ and _i_), and the height read off from the gauge tube (_n_). The syrup can be removed, for the purpose of ascertaining its consistency, from the gauge cylinder by means of either of the three pipes (_b_, _c_, _d_). By _u_ steam can be admitted to the boiling-pan and condenser. _e_ is generally of stout glass, and enables the state of the juice to be seen. _g_ is the grease cock, _f_ the manhole. The condenser consists of the jacket (B), arranged to prevent the mixing of the juice with the water used for condensation. _x_ is the gauge. The pipe (_m_) conveying water to the condenser terminates in a rose. _z_ is a thermometer showing the interior temperature of the boiling-pan.

The air-pump being set in operation the tube (_c_) is opened, and the gauge cylinder filled by the juice rising from _q_. By closing _m_ and opening _y_ the juice is admitted to the boiling-pan. When this is half full the steam pipe (_s_) is opened, the steam quickly heating the contents of the pan to the boiling point. The condenser is then placed in working; by opening the pipe (_l_) the steam of the juice passes into the condenser, where it is speedily condensed, passing with the water through β.

=Sugar, Diabet′ic.= Grape sugar found in the urine of persons labouring under diabetes. In _diabetes insipidus_, a substance having the general properties of a sugar, but destitute of a sweet taste, appears to be produced (Thénard.)

=Sugar, Gel′atin.= See GLYCOCINE.

=Sugar, Grape=, C_{6}H_{12}O_{6}.H_{2}O. _Syn._ GLUCOSE, FRUIT SUGAR; SACCHARUM UVÆ, S. FRUCTUS, L. This substance is found in the juice of grapes and other fruit, in the urine of diabetic patients, and in the liquid formed by acting on starch and woody fibre with dilute sulphuric acid.

_Prep._ 1. From the juice of ripe grapes or an infusion of the ripe fruit (raisins), by saturating the acid with chalk, decanting the clear liquid, evaporating to a syrup, clarifying with white of egg or bullock’s blood, and then carefully evaporating to dryness; it may be purified for chemical purposes by solution and crystallisation in either water or boiling alcohol. Like other sugar, it may be decoloured by animal charcoal.

2. From honey, by washing with cold alcohol, which dissolves the fluid syrup and leaves the solid crystallisable portion.

_Prop._ It is less sweet and less soluble than cane sugar, requiring 1-1/2 part of cold water for its solution; instead of bold crystals, it forms granular warty masses, without distinct crystalline faces; it does not easily combine with either oxide of calcium or oxide of lead; with heat, caustic alkaline solutions turn it brown or black, but it dissolves in oil of vitriol without blackening, the reverse being the case with cane sugar; with chloride of sodium it forms a soluble salt, which yields large, regular, and beautiful crystals. Sp. gr. 1·400.

The various fruits contain grape sugar in the following proportions:

Per Cent.
Peach 1·57
Apricot 1·80
Plum 2·12
Raspberry 4·00
Blackberry 4·44
Strawberry 5·73
Bilberry 5·78
Currant 6·10
Plum 6·26
Gooseberry 7·16
Cranberry 7·45 (according to Fresenius).
Pear 8·02 to 10·8 (E. Wolff).
Apple 8·37 (Fresenius).
” 7·28 to 8·04 (E. Wolff).
Sour cherry 8·77
Mulberry 9·19
Sweet cherry 10·79
Grape 14·93

_Obs._ Cane sugar is converted into grape sugar during the process of fermentation, and by the action of acids. See SUGAR, and SUGAR, STARCH (_below_).

=Sugar, Maple.= _Syn._ SACCHARUM ACERINUM, L. From the juice of the sugar maple. It is identical with cane sugar.

In the United States and the British Colonies of North America considerable quantities of this sugar are made. The juice is obtained by boring through the bark of the tree to a depth of about a quarter or half an inch. Each tree has generally two perforations made in it, and they are always made on that side of the tree which faces towards the south, and at a distance of about 20 inches from the ground. The juice flows into suitable vessels, into which it is conducted by reeds placed under the perforations. The period chosen for tapping the trees is that during which it is known the sap is ascending, from March to May. Sometimes the tree undergoes a second tapping in the autumn, but this is not generally practised, inasmuch as it is injurious to the tree. A daily yield of 6 galls, of juice from each incision is looked upon as a ‘good run,’ and if this 6 gall. be the produce of an old tree or ‘old bush’ they will yield 1 lb. of sugar. In a young tree or ‘young bush’ the yield of sugar from the same quantity of sap is only half. By proper care the same tree may be tapped 20 or 30 years following. Unlike the sugar-cane the juice in the maple is the richest in sugar the higher it is found from the ground. The concentrated saccharine liquid is concentrated every 24 hours. The raw crystallised sugar undergoes no refining, and being made into blocks is then sent to market.

=Sugar, Milk.= C_{12}H_{22}O_{11}.H_{2}O. _Syn._ SUGAR OF MILK, LACTIN; SACCHARUM LACTIS (Ph. D.), L. _Prep._ Gently evaporate clarified whey until it crystallises on cooling, and purify the crystals by digestion with animal charcoal and repeated crystallisations.

_Prop., &c._ White, translucent, very hard cylindrical masses or four-sided prisms; soluble in about 6 parts of cold and in 2 parts of boiling water; nearly insoluble in alcohol and ether; ammoniacal plumbic acetate precipitates it from its solutions. When an alkaline solution of grape sugar is boiled with the salts of copper, silver, or mercury, it reduces them; it produces right-handed rotation of a ray of polarised light; by boiling with dilute acid it is converted into _galactose_ (C_{6}H_{12}O_{6}); treated with nitric acid it yields mucic acid, with small quantities of saccharic, oxalic, and tartaric acid. Milk sugar is unsusceptible of the vinous fermentation, except under the action of dilute acids, which convert it into grape sugar; in solution, it is converted into lactic or butyric acid by the action of caseine and albuminous matter. Milk contains about 5% of it. (Boussingault.)

_Obs._ Sugar of milk is chiefly imported from Switzerland. In this country it is chiefly used as a vehicle for more active medicines, especially among the homœopathists.

=Sugar, Starch.= _Syn._ POTATO SUGAR, FÆCULA S. This is grape sugar obtained by the action of diastase on starch, in the manner noticed under GUM (British), or by the action of dilute sulphuric acid on starch, or of the strong acid on lignin, or on substances containing it.

_Prep._ 1. From corn. The corn is first steeped in soda lye; it is then ground wet and passed through revolving sieves to separate the husks and gluten. The starch is carried through long troughs, in which are placed transverse pieces of wood, against which the solid particles of starch lodge, and are thus separated from the washing waters. These wash waters run into a large cistern, where it undergoes fermentation into weak vinegar. The starch in the wet state is then put into a mash tub and treated for from 3 to 8 hours with 1 per cent. of sulphuric acid. The acid liquor is neutralised with chalk and evaporated in vacuum pans; and after being separated from the sulphate of lime it is run into barrels and allowed to crystallise. The grape sugar is sometimes manufactured in blocks 6 inches square, and dried on plaster plates in a current of dry air, as hot air would decolorise it. Large quantities of grape sugar manufactured as above are now produced in the United States, particularly in New Orleans, Buffalo, and Brooklyn. A considerable amount from the same source reaches this country from the Continent, and is employed in our breweries. When specially prepared for the use of the latter the blocks are crushed into small pieces about the size of malt grains. Our excise authorities prohibit the entrance of glucose into a brewer’s premises in the liquid state. In the brewing of pale sparkling ales grape is esteemed more than either cane sugar or malt, and is said to yield a more sound and wholesome liquor, and one free from the acidity, impurity, and treacly sweetness frequently found in beers brewed from raw or inferior sugars. Glucose may also be obtained from cellulose, but the process is too expensive to admit of being practically worked.

2. Potato starch, 100 parts; water, 00 parts; sulphuric acid, 6 parts; mix, boil for 35 or 40 hours, adding water, to make up for evaporation; then saturate the acid with lime or chalk, decant or filter, and evaporate the clear liquor. Under pressure the conversion is more rapid. _Prod._ 105%.

3. “The starch of potatoes can be converted into glucose by digestion for a few hours with parings of the potato. This operation is largely practised by German farmers in the preparation of food for fattening hogs. An excellent starch sugar can be prepared from Indian corn, which will yield alcohol one eighth cheaper, and quite as pure as that from cane sugar.”[208]

[Footnote 208: ‘Journ. of Applied Chemistry.’]

4. Shreds of linen or paper, 12 parts; strong sulphuric acid, 17 parts (Braconnot; 5 of acid, and 1 of water——Vogel); mix in the cold; in 24 hours dilute with water, and boil it for 10 hours; then neutralise with chalk, filter, evaporate to a syrup, and set the vessel aside to crystallise. _Prod._ 114%. Sawdust, glue, &c., also yield grape sugar by like treatment. See LIGNIN.

=Sugar from other Sources.= Considerable quantities of East Indian cane sugar are yielded by certain Indian palms, the principal of which are the _Arenga saccharifera_ and the _Phœnix sylvestris_ or wild date. Another source whence large quantities of cane sugar are procured is the _Sorghum saccharatum_ or sugar grass. This plant is exclusively grown in Ohio, and yields annually more than 15,000,000 gall. of juice, which is made into sugar.

_Melezitose_ (C_{12}H_{22}O_{11}). From larch manna.

_Mycose_ or _trehalose_ (C_{12}H_{22}O_{11}). From Turkish manna.

_Melitose_ (C_{12}H_{24}O_{12}). From the eucalyptus.

_Maltose_ (C_{12}H_{24}O_{12}). From malt.

_Eucalen_ (C_{6}H_{12}O_{6}). By fermentation of melitose.

_Sorbin_ (C_{6}H_{12}O_{6}). From the berries of the service tree.

_Effects of the varieties of Sugar on Polarised Light._ Both sucrose, or cane sugar, and dextrose produce rotation upon a ray of polarised light. The plane of rotation is rotated to the right by sucrose rather more powerfully than by dextrose. It is remarkable that the uncrystallisable sugar of fruits produces an opposite rotation, viz. to the left. Since the degree of rotation is proportionate in columns of equal length to the quantity of sugar present, it has been proposed to employ this property in order to determine the quantity of sugar present in syrups.[209] The following, according to Berthelot, are the rotatory powers of the different varieties of sugar, if equal weights of each are dissolved in an equal bulk of water; the quantities of each sugar are calculated for the formulæ annexed:

[Footnote 209: Miller.]

+----------------------+--------------------+-----------+-----------------+
| | | | Temperature. |
| Variety. | Formula. | Rotation. | |
| | | |° Fahr. |° Cent. |
+----------------------+--------------------+-----------+--------+--------+
| | | | | |
|Sucrose (cane sugar) |(C_{12}H_{22}O_{11})|Right 73·8°| | |
|Melezitose |(C_{12}H_{22}O_{11})| ” 94·1°| | |
|Mycose |(C_{12}H_{22}O_{11})| ” 193° | | |
|Melitose |(C_{12}H_{24}O_{12})| ” 102° | | |
|Dextrose (grape sugar)|(C_{6}H_{12}O_{6}) | ” 57·4°| | |
|Malt sugar |(C_{6}H_{12}O_{6}) | ” 172° | | |
|Lœvulose (fruit | | | | |
| sugar) |(C_{6}H_{12}O_{6}) |Left 106° | 56 | 13·3 |
|Eucalin |(C_{6}H_{12}O_{6}) |Right 50° | | |
|Sorbin |(C_{6}H_{12}O_{6}) |Left 46·9°| | |
|Lactose (milk sugar) |(C_{6}H_{12}O_{6}) |Right 56·4°| | |
|Glucose of ditto | | | | |
| (galactose) |(C_{6}H_{12}O_{6}) | ” 83·3°| | |
|Inverted cane sugar |(C_{6}H_{12}O_{6}) |Left 28° | 57 | 13·9 |
| | | | | |
+----------------------+--------------------+-----------+--------+--------+

=SUGAR-BOILING.= The art or business of the confectioner or sugar-baker; the candying of sugar. The stages are as follow:——Well clarified and perfectly transparent syrup is boiled until a ‘skimmer’ dipped into it, and a portion ‘touched’ between the forefinger and thumb, on opening them, is drawn into a small thread, which crystallises and breaks. This is called a ‘weak candy height.’ If boiled again, it will draw into a larger string, and if bladders may be blown through the ‘drippings’ from the ladle, with the mouth, it has acquired the second degree, and is now called ‘bloom sugar.’ After still further boiling, it arrives at the state called ‘feathered sugar.’ To determine this re-dip the skimmer, and shake it over the pan, then give it a sudden flirt behind, and the sugar will fly off like feathers. The next degree is that of ‘crackled sugar,’ in which state the sugar that hangs to a stick dipped into it, and put directly into a pan of cold water, is not dissolved off, but turns hard and snaps. The last stage of refining this article reduces it to what is called ‘carmel sugar,’ proved by dipping a stick first into the sugar, and then into cold water, when, on the moment it touches the latter, it will, if matured, snap like glass. It has now arrived at a ‘full candy height.’ Care must be taken throughout that the fire is not too fierce, as, by flaming up against the sides of the pan, it will burn and discolour the sugar; hence the boiling is best conducted by steam heat.

Any flavour or colour may be given to the candy by adding the colouring matter to the syrup before boiling it, or the flavouring essences when the process is nearly complete. See STAINS, &c.

=SUGAR CAN′DY.= _Syn._ SACCHARUM CANDIDUM, S. CRYSTALLINUM, S. CRYSTALLIZATUM, L. Sugar crystallised by leaving the saturated syrup in a warm place (90 to 100° Fahr.), the shooting being promoted by placing sticks, or threads, at small distances from each other in the liquor; it is also deposited from compound syrups, and does not seem to retain much of the foreign substances with which they are loaded. Brown sugar candy is prepared in this way from raw sugar; white do., from refined sugar; and red do., from a syrup of refined sugar which has been coloured red by means of cochineal.

Sugar candy is chiefly used as a sweetmeat; and, being longer in dissolving than sugar, in coughs, to keep the throat moist; reduced to powder, it is also blown into the eye, as a mild escharotic in films or dimness of that organ.

=SUGAR OF LEAD.= Acetate of lead.

=SUGAR PLUMS.= _Syn._ BON-BONS, DRAGÉES, Fr. These are made by various methods, among which are those noticed under DROPS (Confectionery), LOZENGES, and PASTILS, to which may be added the following:——Take a quantity of sugar syrup, in the proportion to their size, in that state called a ‘blow’ (which may be known by dipping the skimmer into the sugar, shaking it, and blowing through the holes, when parts of light may be seen), and add a drop or two of any esteemed flavouring essence. If the ‘bon-bons’ are preferred white, when the sugar has cooled a little, stir it round the pan till it grains and shines on the surface. When all is ready, pour it through a funnel into little clean, bright, leaden moulds, which must be of various shapes, and be previously slightly moistened with oil of sweet almonds; it will then take a proper form and harden. As soon as the plums are cold, take them from the moulds; dry them for two or three days in the air, and put them upon paper. If the bon-bons are required to be coloured, add the colour just as the sugar is ready to be taken off the fire.

CRYSTALLISED BON-BONS are prepared by dusting them with powdered double-refined lump sugar before drying them.

LIQUEUR BON-BONS, now so beautifully got up by the Parisian confectioners, are obtained by pressing pieces of polished bone or metal into finely powdered sugar, filling the hollow spaces so formed with saturated solutions of sugar in the respective liqueurs, and then spreading over the whole an ample layer of powdered sugar. In the course of three or four days the bon-bons may be removed, and tinted by the artist at will. Instead of white powdered sugar ordered above, coloured sugar may be used. These bon-bons are found to be hollow spheres, containing a small quantity of the spirit or liqueur employed, and will bear keeping for many months. See SWEETMEATS, &c.

=SUGARS (Medicated).= _Syn._ SACCHARIDES; SACCHARA MEDICATA, L.; SACCHAROLÉS, SACCHARURES, Fr. Some of these are prepared by moistening white sugar with the medicinal substance, then gently drying it, and rubbing it to powder; in other cases they are obtained in the manner noticed under PULVERULENT EXTRACTS, or OLEOSACCHARUM. The most valuable preparation of this class in British pharmacy is the saccharated carbonate of iron (FERRI CARBONAS CUM SACCHARO——Ph. L.).

=SUINT, Gas from.= By this is understood a gas prepared from the fatty materials present in the soap-suds used in washing raw wool and spun yarns. The water containing the suint and soap-suds is run into cisterns, and is there mixed with milk of lime, and left to stand for twelve hours. A thin precipitate is formed, which, after the supernatant clear liquor has been run off, is put upon coarse canvas for the purpose of draining off any impurities, sand, hair, &c., while the mass which runs through the filter is put into a tank, in which it forms, after six or eight days, a pasty mass, which, having been dug out and moulded into bricks, is dried in open air. At Rheims the first wash-water of the wool is used for making both gas and potash, because the water contains no soap and only suintate of potash. Havrez, at Verviers, has recently proposed to employ suint——which, by-the-bye, is very rich in nitrogen——for the purpose of making ferrocyanide of potassium.

The dried brick-shaped lumps are submitted to distillation, yielding a gas which does not require purification, and which possesses an illuminating power three times that of good coal gas. The wash-water of a wool-spinning mill with 20,000 spindles yields daily, when treated as described, about 500 kilos of dried suinter, as the substance is technically called. One kilo of this substance yields 210 litres of gas. Annually about 150,000 kilos of suinter are obtained, and this quantity will yield 31,500,000 litres = 1,112,485 cubic feet of gas. Every burner consuming 35 litres of gas per hour, and taking the time of burning at 1200 hours, the quantity of gas will suffice for 750 burners, and as a spinning mill of 20,000 spindles only requires 500 burners, there is an excess of gas supply available for 250 other burners, or the owner may dispose of 5000 kilos of suinter, which is valued at Augsburgh at about 3s. per 50 kilos, and at about 4s. at Mulhouse.[210]

[Footnote 210: Wagner’s ‘Chemical Technology.’]

=SUL′PHATE.= _Syn._ SULPHAS, L. A salt of sulphuric acid.

=SUL′PHIDE.= A salt consisting of sulphur and a metal or other basic radical. See SULPHURETTED HYDROGEN.

=SULPHINDYL′IC ACID.= _Syn._ SULPHINDIGOTIC ACID. An intensely blue pasty mass, formed by dissolving 1 part of indigo in about 15 parts of concentrated sulphuric acid. See SULPHATE OF INDIGO.

=SUL′PHITE.= A salt of sulphurous acid.

=SULPHOCARBOLIC ACID.= (SULPHOCARBOLATES.) Carbolic acid, when acted upon by bases, yields a class of salts termed carbolates. These compounds are very unstable; they readily absorb water from the air, which sets free carbolic acid; they usually have the powerful odour of the latter. When, however, equivalent weights of carbolic and sulphuric acids are mixed, union takes place, a definite double acid (sulphocarbolic) results, and the salts formed by this double acid with the various bases are entirely different from the simple salts of carbolic acid. They are very stable, very soluble, possess neither odour nor taste of carbolic acid, and are singularly beautiful in crystalline form.

=Sulphocarbolic Acid= (HC_{6}H_{3}SO_{4}) is obtained by the crystallisation in long colourless needles; unlike carbolic acid, it is soluble in water, alcohol, and ether, in any proportions.

=Sulphocarbolate of Calcium= [Ca(C_{6}H_{5}SO_{4})_{2} + Aq.] is obtained in very long, fine, densely interlacing crystals, which form in bulk, by their interlacement, a porous mass. Unlike the usual lime-salts, this is exceedingly soluble. This fact overcomes the great difficulty of treatment when in disease there is a deficiency of lime in the body, especially in rickets, in which disease the want of lime in the bones gives rise to distortions. The sulphocarbolate of magnesium crystallises in large, clear, rhombic prisms, easily soluble in water.

=Sulphocarbolate of Copper= [Cu(C_{6}H_{5}SO_{4})_{2}] forms fine prismatic crystals of a blue colour. It is used as the zinc sulphocarbolate, chiefly as a lotion and dressing, in the proportion of 3 to 10 grains to the ounce of distilled water.

=Sulphocarbolate of Iron= [Fe(C_{6}H_{5}SO_{4})_{2}] is in colourless or pale green rhombic plates. It is readily administered, and seems in some instances to be preferred to other salts of iron. It seems to have been of especial use in the skin diseases of children, wherein there is much formation of matter.

=Sulphocarbolate of Sodium= [Na(C_{6}H_{5})SO_{4}.Aq] is in brilliant, clear, rhombic prisms. The salt is very soluble in water. This salt can be administered as a medicine in doses of 20 to 60 gr.; it is slowly decomposed in the textures, carbolic acid being evolved. It thus becomes a very simple means of obtaining the beneficial effects of the administration of this antiseptic without the difficulties and dangers which attend it in its uncombined irritant and caustic form. It has proved of great service in the treatment of infectious diseases. Administered in the severest cases of diphtheria, malignant scarlet fever, typhoid, erysipelas, &c., the remedy has proved of extreme value.

=Sulphocarbolate of Zinc= [Zn(C_{6}H_{5}SO_{4})_{2}] is chiefly employed in solution as a lotion. By high surgical authorities it is considered to answer all the purposes of the antiseptic dressing of carbolic acid. It is inodorous, and has very slight irritating action.

=The Sulphocarbolates of Potassium= [KC_{6}H_{5}SO_{4}] =and Ammonium= [NH_{4}C_{6}H_{5}SO_{4}] are also brilliant crystals; they are freely soluble, administered with the greatest ease, and have been used with success as remedial agents.

=SULPHOCYAN′OGEN.= A well-defined salt radical, containing sulphur united to the elements of cyanogen. Its compounds are the sulphocyanides, most of which may be formed by directly saturating hydrosulphocyanic acid with the oxide or hydrate of the base; or, from the sulphocyanide of potassium and a soluble salt of the base, by double decomposition.

=SULPHOFORM.= _Syn._ SULPOFORMUM. An oily liquid obtained by distilling one part of iodoform with three of sulphide of mercury.

=SULPHOPHE′NIC ACID.= A synonym of sulphocarbolic acid. See SULPHOCARBOLATES.

=SULPHOVIN′IC ACID.= C_{2}H_{5}HSO_{4}. _Syn._ SULPHETHYLIC ACID; ACIDUM SULPHOVINICUM, L. This substance is formed by the action of heat on a mixture of alcohol and sulphuric acid; it is the intermediate product which is developed in the preparation of ether. The salts are called sulphovinates or sulphothylates.

=SUL′PHUR.= [Eng., L.] _Syn._ BRIMSTONE; SOUFRE, Fr. An elementary substance. That of commerce is chiefly imported from Sicily and Italy, and is a volcanic production.

_Var._ The principal of these are:

AMORPHOUS SULPHUR, BROWN S.; SULPHUR AMORPHUM, S. FUSCUM, S. INFORME, S. RUBRUM, L. Prepared from sublimed sulphur, by melting it, increasing the heat to from 320° to 350° Fahr., and continuing it at that temperature for about half an hour, or until it becomes brown and viscid, and then pouring it into water. In this state it is ductile, like wax, may be easily moulded in any form, is much heavier than usual, and when it has cooled does not again become fluid until heated to above 600° Fahr. The same effect is produced more rapidly by at once raising the temperature of the melted mass to from 430° to 480° Fahr.

PRECIPITATED SULPHUR, HYDRATE OF SULPHUR, MILK OF S.; SULPHURIS HYDRAS, LAC SULPHURIS, SULPHUR PRÆCIPITATUM (Ph. L.). _Prep._ 1. From sublimed sulphur, 1 part; dry and recently slaked lime, 2 parts; water, 25 parts, or q. s.; boil for 2 or 3 hours, dilute with 25 parts more of water, filter, and precipitate with dilute hydrochloric acid; drain, and well wash the precipitate, and dry it by a gentle heat. Resembles sublimed sulphur in its general properties, but is much paler, and in a finer state of division.

2. (B. Ph.) Sublimed sulphur, 5 oz.; slaked lime, 3 oz.; hydrochloric acid, 3 fl. oz., or q. s.; distilled water, q. s. Heat the sulphur and lime, previously well mixed, in 1 pint of water, stirring diligently with a wooden spatula, boil for 15 minutes and filter. Boil the residue again in 1/2 pint of water and filter. Let the united filtrates cool, dilute with 2 pints of water, and in an open place, or under a chimney, add in successive quantities the hydrochloric acid previously diluted with 1 pint of water until effervescence ceases, and the mixture acquires an acid reaction. Allow the precipitate to settle, decant off the supernatant liquid, pour on fresh distilled water, and continue the purification by affusion of distilled water and subsidence, until the fluid ceases to have an acid reaction, and to precipitate with oxalate of ammonia. Collect the precipitated sulphur on a calico filter, wash it once with distilled water, and dry it at a temperature not exceeding 120° Fahr.

_Prop._ A greyish-yellow powder free from grittiness, and with no smell of sulphuretted hydrogen.

_Obs._ Many pharmacists regard LAC SULPHURIS and SULPHUR PRECIPITATUM as distinct substances, and assume that by milk of sulphur is intended a preparation made by an old pharmacopœial process, in which sulphuric acid being employed, the sulphur so precipitated contains from 50 to 75 per cent. of sulphate of lime. Pareira, Royle, Atfield, and some other authorities, hold that LAC SULPHURIS and SULPHUR PRECIPITATUM are synonymous; whilst others, including Professor Redwood (one of the compilers of the B. P.) entertain a contrary opinion.

ROLL SULPHUR, CANE S., STICK S.; SULPHUR IN BACCULIS, S. IN ROTULIS, S. ROTUNDUM, L. This is crude sulphur, purified by melting and skimming it, and then pouring it into moulds. That obtained during the roasting of copper pyrites, and which forms the common roll sulphur of England, frequently contains from 3 to 7% of yellow arsenic.

SUBLIMED SULPHUR, FLOWERS OF SULPHUR; FLORES SULPHURIS, SULPHUR (Ph. L.), SULPHUR SUBLIMATUM (B. P., Ph. E. & D.), L. Prepared by subliming sulphur in iron vessels. For medical purposes, it is ordered to be well washed with water, and dried by a gentle heat. “A slightly gritty powder, of a fine greenish-yellow colour, without taste and without odour till heated.” (B. P.)

SULPHUR VIVUM, BLACK SULPHUR, CRUDE S., HORSE BRIMSTONE; SULPHUR NIGRUM, S. CABALLINUM, S. GRISEUM, L. This is crude native sulphur. It is a grey or mouse-coloured powder. The residuum in the subliming pots from the preparation of flowers of sulphur is now commonly substituted for it. It generally contains much arsenic, and is consequently very poisonous.

_Pur._ The sublimed sulphur of the shops is now, in general, of respectable quality, but the precipitated sulphur frequently contains about 2/3 of its weight of sulphate of lime (plaster of Paris), owing to the substitution of sulphuric acid for hydrochloric acid in its manufacture.[211] This is readily detected by strongly heating a little of the suspected sample in an iron spoon or shovel, when the sulphur is burnt or volatilised, and leaves behind the sulphate of lime as a white ash; this, when mixed with water, and gently dried, gives the amount of the adulteration. A still simpler plan is to dissolve out the sulphur in the sample with a little hot oil of turpentine or liquor of potassa; the undissolved portion is foreign matter.

[Footnote 211: See PRECIPITATED SULPHUR, above.]

_Prop._ Sulphur melts to a clear thin fluid, and volatilises at about 232° Fahr., and in open vessels rapidly takes fire, burning with a bluish flame. It is insoluble in both water and alcohol; it is soluble in oil of turpentine and the fatty oils, and freely so in bisulphide of carbon and hot liquor of potassa. With oxygen it unites to form sulphurous anhydride, and with the metals to form sulphides. Sp. gr. 1·982 to 2·015.

_Estim._ The determination of the quantity of sulphur, phosphorus, and chlorine, in a state of combination, especially in organic mixtures, is often rather troublesome. The proportion of sulphur is best determined by oxidising a known weight of the substances by strong nitric acid, or by fusing it in a silver vessel with 10 or 12 times its weight of pure hydrate of potassa and about half as much nitre. The sulphur is thus converted into sulphuric acid, the quantity of which can be determined by dissolving the fused mass in water, acidulating the solution with nitric acid, adding a salt of baryta, and weighing the resulting sulphate. Phosphorus is, in like manner, oxidised to phosphoric acid, the quantity of which is determined by precipitation in combination with sesquioxide of iron, or otherwise. The chlorine is correctly determined by placing a small weighed portion in a combustion-tube, which is afterwards filled with fragments of pure quicklime. The lime is then brought to a red heat, and the vapour of the liquid driven over it, when chloride of calcium is formed. The contents of the tube, when cold, are dissolved in dilute nitric acid, filtered, the chlorine precipitated by nitrate of silver, and the chlorine weighed under the form of chloride of silver. See ORGANIC SUBSTANCES.

_Uses, &c._ Sulphur is extensively used in the manufacture of gunpowder, in bleaching, &c., &c. When swallowed, it acts as a mild laxative and stimulating diaphoretic; and has hence been long taken in various chronic skin diseases, in pulmonary, rheumatic, and gouty affections, and as a mild purgative in piles, prolapsus ani, &c. Externally, it is extensively used in skin diseases, especially the itch, for which it appears to be a specific.——_Dose_, 20 to 63 gr., in sugar, honey, treacle, or milk.

=Sulphur, Chlo′′rides of.= Several of these compounds exist but the following are the most important. 1. (DICHLORIDE, S_{2}Cl_{2}.) Prepared by passing dry chlorine gas over the surface of sulphur melted in a bulbed-tube or small retort connected with a well-cooled receiver. The product is a deep orange-yellow and very mobile liquid, which possesses a disagreeable odour, and boils at 280° Fahr. It is soluble in bisulphide of carbon, and in benzol, without decomposing. It dissolves sulphur in large quantities, especially when heated. A solution of the dichloride with excess of sulphur in crude benzol is used for vulcanising caoutchouc.

2. (CHLORIDE, HYPOCHLORIDE, or HYPOCHLORITE of the shops; SULPHURIS CHLORIDUM, S. HYPOCHLORIDUM, S. HYPOCHLORITIS, L.) This is prepared by spreading washed sulphur thinly on the bottom of a wooden box, or other chamber, and passing chlorine gas slowly over until it ceases to be absorbed.

_Obs._ This last compound is of variable and undetermined constitution. It has been recommended for internal use, by Derksengi, in old gouty affections, combined with pains in the stomach, and in severe nervous fever.——_Dose_, 1/2 to 2 gr.; dissolved in ether, and taken with old Hungary wine. It is also used externally in _psoriasis inveterata_, and other skin diseases.

=Sulphur, I′odide of.= S_{2}I_{2}. _Syn._ BINIODIDE OF SULPHUR; SULPHURIS IODIDUM (Ph. L.), SULPHUR IODATUM (Ph. D.), L. _Prep._ Into a glass flask put 1 part of sublimed sulphur, and over it place 4 parts of iodine; insert the cork loosely, and place the flask in a water bath; as soon as its contents melt, stir them with a glass rod, replace the cork, remove the bath from the fire, and let the whole cool together. When cold, break the iodide into pieces, and place it in a wide-mouthed stoppered bottle. In this way a beautiful semi-crystalline, dark grey mass, resembling antimony, is obtained. The formulæ of the B. P., Ph. L., E., & D., Ph. U. S., & P. Cod., are essentially similar. The Ph. D. orders the two substances to be powdered and mixed before heating them.

_Uses, &c._ It is stimulant and alterative. An ointment made of it has been recommended by Biett and others in tuberculous affections of the skin, in lepra, psoriasis, lupus, porrigo, &c.

Iodide of sulphur stains the skin like iodine, and is readily decomposed by contact with organic substances.

=SULPHURA′TION.= The process by which silk, cotton, and woollen goods, straw plait, &c., are subjected to the fumes of burning sulphur, or sulphurous acid, for the purpose of bleaching or decolouring them. On the large scale, this is effected in closed apartments, called ‘sulphuring rooms,’ to which sufficient air only is admitted to keep up the slow combustion of the sulphur. On the small scale, as for straw hats, bonnets, &c., a large wooden chest is frequently employed in the same way.

=SUL′PHURET.= _Syn._ SULPHIDE; SULPHURETUM, SULPHIDUM, L. See SULPHIDE.

=SULPHURET′TED HY′DROGEN= (H_{2}S). _Syn._ HYDROGEN SULPHIDE, DIHYDRIC SULPHIDE, HYDRIC SULPHIDE; HYDROSULPHURIC ACID. Sulphuretted hydrogen occurs in nature amongst the gaseous products given off by volcanoes, as well as in many mineral waters, amongst which may be instanced those of Harrogate, in England, of Moffat, in Scotland, and of Barèges, Eaux Bonnes, St. Sauveur, &c., in the Pyrenees. It is also evolved from decaying animal matter containing albumen, such as white-of-egg, as well as from putrisable animal and vegetable substances, when in contact with a soluble sulphate, and is always one of the gases present in the air of drains and sewers. Sulphuretted hydrogen may be procured by the direct union of hydrogen and sulphur, as by passing hydrogen into boiling sulphur. But this method of procuring it is rarely, if ever, adopted. The much readier process of acting upon a metallic sulphide by an acid constitutes the means by which the chemist almost invariably obtains this gas.

The details of the process are as follows:

1. About an ounce of ferrous sulphide, previously reduced to small pieces, is placed in a bottle, and then there is poured on to it a fluid ounce of sulphuric acid diluted with 8 times its bulk of water, when the following reaction ensues:——FeS + H_{2}SO_{4} = H_{2}S + FeSO_{4}.

The gas which is immediately and copiously given off may be collected in an apparatus, a drawing and description of which are given below.

The diluted acid, having become cool, is poured through the bulb-shaped aperture down the glass tube upon the ferrous sulphide, and the evolved gas passing through the small intermediate wash-bottle into the bottle at the reader’s right hand, is absorbed by the water therein contained, the operation being continued until the water has become saturated with the gas. The glass tubes are connected with vulcanised india rubber, as shown in the above plate. Diluted hydrochloric acid is frequently substituted for sulphuric.

2. In the above process, the gas obtained, owing to the contamination of the iron sulphide, is more or less impure. When sulphuretted hydrogen is required in a state of purity, 1 oz. of antimonious sulphide must be employed instead of the iron sulphide, and instead of sulphuric 3 or 4 parts of hydrochloric acid. As heat must be applied to the mixture, it will be necessary to substitute a flask for the larger bottle, and to support it on a retort stand. In other respects the apparatus needs no alteration.

3. Sulphuretted hydrogen is also obtainable when paraffin is heated at a moderately elevated temperature with sulphur, the reaction being attended with an abundant evolution of the gas, and a simultaneous separation of carbon.

⁂ The solution of sulphuretted hydrogen, which is so indispensable to the chemist, and consequently in such constant requisition in the laboratory, unfortunately very quickly decomposes into water, and sulphur, which deposits at the bottom of the vessel containing it. To diminish as much as possible the tendency to deterioration, the solution should be made either with boiled water, or with the clear spoilt solution.

_Qualities, &c._ Sulphuretted hydrogen is a colourless inflammable gas, somewhat heavier than air, its specific gravity being 1·174. When ignited, it burns with a bluish flame, to water and sulphurous anhydride if the combustion take place in a sufficient quantity of air, but if the supply of air be too limited, sulphur is deposited. Under a pressure of 17 atmospheres it is condensed to a colourless and very mobile fluid, which boils at 79·6° F., and freezes at 72·8° F. to a transparent solid. Both the gas and its aqueous solution exercise a feebly acid reaction on litmus.

Sulphuretted hydrogen is highly poisonous; when inhaled in any quantity it causes fainting; and in smaller quantities, even when considerably diluted by air, if breathed for any length of time, it acts as a dangerous depressant and insiduous poison. Upon the lower animals it acts with fatal rapidity, even if diluted with 800 or 1000 parts of atmospheric air. Transmitted through tubes heated to redness, sulphuretted hydrogen becomes partially decomposed into its elements, hydrogen and sulphur. Water at 32° F. takes up 4·37 times its bulk of this gas, and at 59, 3·23 times its hulk, hence the importance of collecting it, over warm water, if required in the gaseous form.

In the presence of moisture, sulphurous anhydride and sulphuretted hydrogen, if equivalent quantities of each react upon each other, become decomposed into sulphur, water, and pentathronic acid; hence the value of sulphurous acid as a disinfectant. The deposited sulphur is found always to occur in the electro-positive condition. Chlorine, bromine, and iodine, also decompose sulphuretted hydrogen with deposition of sulphur, and formation of hydrochloric, hydrobromic, and hydriodic acids.

_Hydrosulphates or Sulphides._ Sulphuretted hydrogen or hydrosulphuric acid, as it is sometimes called, when brought into contact with bases in solution, gives rise to compounds, which by some chemists are regarded as hydrosulphates, or combinations of the base with hydrosulphuric acid; and by others as sulphides or combinations of the metal with sulphur, the latter reaction being attended with the elimination of water, as when a base is acted upon by hydrochloric acid. By those who hold the former view the reaction would be as follows:

K_{2}O + H_{2}S = K_{2}O_{1}H_{2}S.

In the latter case it would be thus represented:

K_{2}O + H_{2}S = K_{2}S + H_{2}O.

The latter is the more general opinion, and it receives support from the fact that when sulphuretted hydrogen is passed into the solution of a metallic salt, an insoluble precipitate of a sulphide of the metal is thrown down. Thus, when the gas is passed into a solution of cupric sulphate, the precipitate consists of hydrated cupric sulphide, the liberated sulphuric acid renders the liquid which was before neutral, acid. The larger number of sulphides so formed, combining with water at the instance of their precipitation, occur as hydrates.

There is also a class of sulphides known as hydrosulphides, sulphydrates, or double sulphides, in which an equivalent of the metal is replaced by an equivalent of hydrogen. Examples of these are the potassic hydrosulphide (KHS), sodic hydrosulphide (NaHS), and ammonic hydrosulphide (H_{4}NHS). No such combinations occur with hydrogen and the metals of the earth proper, and of the iron group.

_Tests._ Many of the hydrosulphates or sulphides may be detected, by dropping on them some hydrochloric acid, when the characteristic smell of sulphuretted hydrogen will be immediately evolved from them. Very small quantities of a sulphide may be detected as follows:——Place the suspected sulphide in a small test tube, on the upper part of which is inserted a piece of blotting paper moistened with a solution of plumbic acetate, then carefully pour some hydrochloric acid on to the substance, when, if it be a sulphide, the paper will become. immediately browned or blackened.

Many small quantities of the soluble sulphides are revealed in neutral or alkaline solutions by the rich purple colour which they form on the addition of a solution of sodic nitro-prusside. Most of them, when heated before the blow-pipe, give off the smell of sulphurous acid.

The quantitative determination of free sulphuretted hydrogen, or of a soluble sulphide in any solution, is conducted as follows:——The liquid to be tested is mixed with a small quantity of a cold solution of starch, made slightly acid with acetic acid. A solution of iodine of known strength, dissolved in potassic iodide is then added, until the liquid just begins to turn blue from the action of the excess of iodine on the starch. In this process the sulphuretted hydrogen converts the iodine into hydriodic acid, whilst sulphur is liberated.

Of course the quantity of sulphuretted hydrogen is calculated from the quantity of iodine employed. The reaction is——

2H_{2}S + 2I_{2} = 4HI + S_{2}.

The value of sulphuretted hydrogen as a reagent has already been alluded to. It throws down most of the metals from solutions of their salts in the form of insoluble sulphides; and each of the sulphides so produced in many cases being distinguished from the others by a special and characteristic colour. The sulphuretted hydrogen thus presents the metal in a form in which it can, in many instances, be easily and with certainty recognised. Thus sulphide of lead is black, of arsenic yellow, of antimony orange, of manganese salmon colour, and of zinc white. By means of sulphuretted hydrogen, also, the chemist is enabled to separate the metals into groups.

For instance, from solutions containing certain metallic salts, sulphuretted hydrogen throws down the metals as sulphides, provided the solution has been previously made slightly acid. Copper, arsenic, tin, and cadmium, are some of the metals thrown down under these conditions.

The salts of iron, nickel, cobalt, and certain others, although they do not yield precipitates under like circumstances, are found to do so if their solutions are made alkaline instead of acid. Again, there are other salts, those of the alkalies and alkaline earths, which, when sulphuretted hydrogen is passed through these solutions, give no precipitates either in acid or alkaline solutions. The chemist, therefore, in the course of an analysis, frequently avails himself of a knowledge of these facts to separate certain metals from each other.

=Hydrogen, Persulphide of.= _Syn._ HYDRIC PERSULPHIDE, HYDROGEN DISULPHIDE. To procure this substance, calcium disulphide (CaS_{2}) in solution is poured into hydrochloric acid diluted with twice its bulk of water. The solution being gently warmed, the persulphide subsides at the bottom as an oily fluid. Hydric persulphide has a great resemblance to hydric peroxide in qualities. It bleaches, and is decomposed, with violence, when brought into contact with the oxides of manganese and silver. It easily decomposes into sulphur and sulphuretted hydrogen.

=SULPHU′RIC ACID.= H_{2}SO_{4}. _Syn._ OIL OF VITRIOL, BRITISH O. OF V., VITRIOLIC ACID†; ACIDUM SULPHURICUM (B. P., Ph. L. & E.), ACIDUM SULPHURICUM VENALE (Ph. D.), ACIDUM VITRIOLICUM†, L. This acid, in a concentrated form, was discovered by Basil Valentine towards the end of the 15th century. At first it was obtained by the distillation of green vitriol, but is now made by the oxidation of sulphurous anhydride, obtained by the combustion either of sulphur or of certain sulphides. In consequence of the growing demand for sulphur in the manufacture of gunpowder, ultramarine, and for the destruction of the vine parasites in the vineyards of France, Italy, and Spain, sulphuric acid is now seldom made by burning sulphur, but, with few exceptions, by roasting iron pyrites, or bisulphide of iron.

The following table will convey an idea of the enormous consumption of this mineral in vitriol making in England alone. The quantities given represent tons.

+-----+-----------------------------------------------------------+-------+
| | Pyrites from[212] | |
|Date.+-------+--------+--------+---------+--------+------+-------+ Sum |
| |Norway.|Germany.|Belgium.|Portugal.| Spain. |Italy.|Sundry |Total. |
| | | | | | | |Places.| |
+-----+-------+--------+--------+---------+--------+------+-------+-------+
|1862 | 4,975 | 6,817 | 9,860 | 53,296 | 33,717 | ... | 2,187 |110,852|
|1863 | 6,736 | 15,409 | 12,059 | 109,180 | 33,213 | ... | 2,628 |179,225|
|1864 |16,087 | 12,751 | 7,069 | 118,489 | 15,529 | ... | 1,065 |170,990|
|1865 |22,229 | 14,727 | 2,121 | 137,787 | 16,393 | ... | 369 |193,626|
|1866 |38,262 | 21,574 | 4,006 | 165,993 | 11,910 | ... | 1,625 |244,596|
|1867 |77,895 | 34,592 | 2,299 | 105,556 | 50,222 | ... | 2,134 |272,698|
|1868 |63,007 | 41,559 | ... | 75,883 | 47,458 | 794 | 1,019 |229,720|
|1869 |63,091 | 13,983 | ... | 140,805 | 99,648 | ... | 2,420 |319,947|
|1870 |67,464 | 14,914 | ... | 174,459 |150,990 | ... | 3,676 |411,512|
|1871 |74,416 | 12,809 | ... | 120,573 |242,163 | ... | 4,581 |454,542|
|1872 |71,665 | 5,682 | ... | 180,329 |257,429 | ... | 2,521 |517,626|
+-----+-------+--------+--------+---------+--------+------+-------+-------+

[Footnote 212: “Development of the Chemical Arts during the last Ten Years,” by Dr A. W. Hofman (‘Chemical News,’ vol. xxv, 1879).]

Of the other sulphides employed in vitriol making may be mentioned galena, or native sulphide of lead, which, when roasted, is made to give up half its sulphur. The chief consumption of this mineral is in the Harz. Copper pyrites is also used in the Harz, as well as in Swansea and Glasgow. Blende, or native sulphide of zinc, is also occasionally had recourse to.

In addition to the above sulphides, the vitriol maker in England, France, and Germany has lately largely availed himself of a compound known as ‘Laming’s mixture,’ which is an impure oxide of iron that has been used in gas manufacture for the removal from the gas of the sulphur. Laming’s mixture is consequently rich in this last element.