Chapter CXII: Act 1895: , may be given to a married woman on applying to (1)

a court of summary jurisdiction if she has been forced by cruelty to leave her husband or has been deserted by him.

United States.--Alimony is granted by the courts of the several states on much the same principle as in England, though in many states the courts of equity as such may grant alimony without divorce or separation proceedings independently of any statute, on the ground that it is just that the husband should support his wife when she lives apart from him for his fault, and since the courts of common law provide no remedy the courts of equity will. This is so in Alabama (Brady v. Brady, 1905, 39 So. Rep. 237), Kentucky, North Carolina, Iowa, California, Ohio, Virginia, South Dakota and the District of Columbia. In other states alimony without such proceedings is allowed by statute, and such alimony is now very general throughout the United States. The usual grounds for the allowance of it are desertion and such conduct as would amount to legal cruelty. After divorce a vinculo, alimony or separate maintenance is sometimes granted on good reason. The marriage must be proven as a fact, but a ``common law'' marriage, i.e. one established by cohabitation and repute, is sufficient. In several states alimony or maintenance is by statute allowed to the husband in certain cases out of the wife's property. This is so in Massachusetts, Virginia, Rhode Island and Iowa. In Oregon he is entitled to one-third of his wife's real estate in addition to maintenance on divorce for her fault. The amount of alimony depends upon the circumstances of each case as in England. Permanent alimony is generally more than when pendenite lite, and usually one-third the husband's income. It may generally be changed from time to time as the circumstances of the parties change. Judgment for alimony is considered a judgment in personam and not in rem, and can only be enforced outside the state where rendered in case the husband has been personally served with process within that state. The remarriage of the man is not sufficient ground for reducing the alimony (Smith v. Smith, 1905, 102 N.W. Rep. 631), but on remarriage of a woman to one able to support her, her former husband being in poor circumstances, it will be reduced (Kiralfy v. Kiralfy, 1901, 36 Wisc. N.S. 407).

ALIN, OSCAR JOSEF (1846--1900), Swedish historian and politician, was born at Falun on the 22nd of December 1846. In 1872 he became docent, and in 1882 professor of political economy at Upsala, of which university he was afterwards rector. In September 1888 he was elected a member of the first chamber of the Riksdag, where he attached himself to the conservative protectionist party, over which, from the first, he exercised great authority. But it is as a historian that Alin is most remarkable. Among his numerous works the following are especially worthy of note: Bidrag till svenska radets historia under. medeltiden (Upsala, 1872); Sveriges Historia, 1511-1611 (Stockholm, 1878); Bidrag till svenska statsrickets historia (Stockholm, 1884-1887); Den svensk-norsk Unionen (Stockholm, 1889-1891), the best book on the Norwego-Swedish Union question from the Swedish point of view; Fjerde Artiklen af Fredstraktaten i Kiel (Stockholm, 1899); Carl Johan och Sveriges yttre politik, 1810-1815 (Stockholm, 1899); Carl XIV. och Rikets Stander, 1840-1841 (Stockholm, 1893). He also edited Sveniska Riksdagsakter, 1521-1554 (Stockholm, 1887), in conjunction with E. Hildebrand, and Sveriges Grundlagar (Stockholm, 1892). He died at Upsala on the 31st of December 1900.

Obituary notice in Sv. Hist. Tidssk. (1901). (R. N. B.)

ALIPUR, a suburb of Calcutta, containing Belvedere House, the official residence of the lieutenant-governor of Bengal, and a number of handsome mansions. It lies within the limits of the south suburban municipality, and is a cantonment of native troops. On the Calcutta maidan, opposite Alipur Bridge, stood two trees under which duels were fought. It was here that the meeting in 1780 between Warren Hastings and Sir Philip Francis took place.

ALIQUOT (a Lat. word meaning ``some,'' ``so many''), a term generally occurring in the phrase ``aliquot part,'' and meaning that one quantity is exactly divisible into another; thus 3 is an aliquot part of 6.

ALIRAJPUR, a native state of India, under the Bhopawar agency in Central India. It lies in Malwa, near the frontier of Bombay. It has an area of 836 sq. m.; and a population (1901) of 50,185. The country is hilly, and many of the inhabitants are aboriginal Bhils. It has from time to time been under British administration. The chief, whose title is Rana, is a Rahtor Rajput. He has an estimated revenue of L. 8700, and pays a tribute of L. 700. The Victoria bridge at Alirajpur was built to commemorate the Diamond Jubilee of 1897.

ALISMACEAE (from the Gr. alisma, a water-plant mentioned by Dioscorides), in botany, a natural order of monocotyledons belonging to the series Helobieae, and represented in Britain by the water plantain, Alisma Plantago, the arrow-head, Sagittaria, the star-fruit, Damasonium, and flowering rush, Butomus (from the Gr. bous, ox, temnein, to cut, in allusion to leaves cutting the tongues of oxen feeding on them). They are marsh- or water-plants with generally a stout stem (rhizome) creeping in the mud, radical leaves and a large, much branched inflorescence. The leaves show a great variety in shape, often

FIG. 1.--Flowering Rush (Butomus umbellatus.) 1, Flower in vertical section; 2, horizontal plan of arrangement of flower.

the same plant, according to their position in, on or above the water. The submerged leaves are long and grass- like, the floating leaves oblong or rounded, while the aerial leaves are borne on long, thin stalks above the water, and are often heart- or arrow-shaped at the base. The flower-bearing stem is tall; the flowers are borne in whorls on the axis as in arrow-head, on whorled branchlets as in water plantain or in an umbel as in Butomus (fig. 1). The flowers are regular and rather showy, generally with three greenish sepals, followed in regular succession by three white or purplish petals, six to indefinite stamens and six to indefinite free carpels. The floral arrangement thus recalls that of a buttercup, a resemblance which extends to the fruit, which is a head of achenes or follicles. The flowers contain honey, and attract flies, short-lipped bees or other small insects by the agency of which pollination is effected. The fruit of Butomus is of interest in having the seeds borne over the inner face of the wall of the leathery pod (follicle). Damasonium derives its popular name, star-fruit, from the fruits spreading when ripe in the form of a star. It is a western

FIG. 2.--Water Plantain (Alisma Plantago.) Plant about 3 ft. high. 1, Flower; 2, same in vertical section; 3, horizontal plan of flower; 4, mature fruit.

Mediterranean plant which spreads to the south of England, where it is sometimes found in gravelly ditches and pools. The order contains about fifty species in fourteen genera, and is widely distributed in temperate and warm zones. Alisma Plantago (fig. 2), a common plant in Britain (except in the north) in ditches and edges of streams, is widely distributed in the north temperate zone, and is found in the Himalayas, on the mountains of tropical Africa and in Australia.

ALISON, ARCHIBALD (1757-1839), Scottish author, son of Patrick Alison, provost of Edinburgh, was born on the 13th of November 1757 at Edinburgh. After studying at the university of Glasgow and at Balliol College, Oxford, he took orders in the Church of England, and was appointed in 1778 to the curacy of Brancepeth, near Durham. In 1784 he married Dorothea, youngest daughter of Professor Gregory of Edinburgh. The next twenty years of his life were spent in Shropshire, where he held in succession the livings of High Ercall, Roddington and Kenley. In 1800 he removed to Edinburgh, having been appointed senior incumbent of St Paul's Chapel in the Cowgate. For thirty-four years he filled this position with much ability, his preaching attracting so many hearers that a new and larger church was built for him. His last years were spent at Colinton, near Edinburgh, where he died on the 17th of May 1839. Alison published, besides a Life of Lord Woodhouselee, a volume of sermons, which passed through several editions, and a work entitled Essays on the Nature and Principles of Taste (1790), based on the principle of association (see under AESTHETICS, p. 288). His elder son, Dr Wilham Pulteney Alison (1790-1859), was a distinguished Edinburgh medical professor.

SIR ARCHIBALD ALISON, Bart. (1792-1867), the historian, was the younger son, and was born at Kenley, Shropshire, on the 29th of December 1792. He studied at the university of Edinburgh, distinguishing himself especially in Greek and mathematics. In 1814 he passed at the Scottish bar, but he did not at once practise. The close of the war had opened up the continent, and Alison set out in the autumn of 1814 for a lengthened tour in France. It was during this period that the idea of writing his history first occurred to him. A more immediate result of the tour was his first literary work of any importance, Travels in France during the Years 1814-1815, written in collaboration with his brother and A. F. Tytler, which appeared in the latter year. On his return to Edinburgh he practised at the bar for some years with very fair success. In 1822 he became one of the four advocates-depute for Scotland. As a result of the experience gained in this office, which he held until 1830, he wrote his Principles of the Criminal Law of Scotland (1832) and Practice of the Criminal Law of Scotland (1833), which in 1834 led to his appointment by Sir Robert Peel to the office of sheriff of Lanarkshire, which ranks next to a judgeship in the supreme court. The office, though by no means a sinecure, gave him time not only to make frequent contributions to periodical literature, but also to write the long-projected History of Europe, for which he had been collecting materials for more than fifteen years. The history of the period from the beginning of the French Revolution till the restoration of the Bourbons in 1815 was completed in ten volumes in 1842, and met with a success almost unexampled in works of its class. Within a few years it ran through ten editions, and was translated into many of the languages of Europe, as well as into Arabic and Hindustani. At the time of the author's death it was stated that 108,000 volumes of the library edition and 439,000 volumes of the popular edition had been sold. A popularity so widespread must have had some basis of merit, and the good qualities of Alison's work lie upon the surface. It brought together, though not always in a well-arranged form, an immense amount of information that had before been practically inaccessible to the general public. It at least made an attempt to show the organic connexion in the policy and progress of the different nations of Europe; and its descriptions of what may be called external history--of battles, sieges and state pageants--are spirited and interesting. On the other hand the faults of the work are numerous and glaring. The general style is prolix, involved and vicious; mistakes of fact and false deductions are to be found in almost every page; and the constant repetition of trite moral reflections and egotistical references seriously detracts from its dignity. A more grave defect resulted from the author's strong political partisanship, which entirely unfitted him for dealing with the problems of history in a philosophical spirit. His unbending Toryism made it impossible for him to give any satisfactory explanation of so complex a fact as the French Revolution, or accurately to estimate the forces that were to shape the Europe of the 19th century. A continuation of the History, embracing the period from 1815 to 1852, which was completed in four volumes in 1856, did not meet with the same success as the earlier work. The period being so near as to be almost contemporary, there was a stronger temptation, which he seems to have found it impossible to resist, to yield to political prejudice, while the materials necessary for a clear knowledge of the influences shaping European affairs were not as yet accessible. The book is now almost wholly out of date. In 1845 Alison was chosen rector of Marischal College, Aberdeen, and in 1851 of Glasgow University. In 1852 a baronetcy was conferred upon him, and in the following year he was made a D.C.L. of Oxford. His literary activity continued till within a short time of his death, the chief works he published in addition to his History being the Principles of Population (1840), in answer to Malthus; a Life of Marlborough (1847, 2nd edition greatly enlarged, 1852); and the Lives of Lord Castlereagh and Sir C. Stewart (1861.) This latter, based on MS. material preserved at Wynyard Park, is still of value, not only as the only available biography, but more especially because Alison's Tory sympathies enabled him to give a juster appreciation of the character and work of Castlereagh than the Liberal writers by whom for many years he was misjudged and condemned (see LONDONDERRY, Robert Stewart, 2nd marquess of). Three volumes of Alison's political, historical and miscellaneous essays were reprinted in 1850. He died at Possil House, Glaagow, on the 23rd of May 1867. His autobiography, Some Account of my Li/e and Writings, edited by his daughter-in-law, Lady Alison, was published in 1883 at Edinburgh. Sir Archibald Alison married in 1825 Elizabeth Glencairn, daughter of Colonel Tytler, by whom he had three children, Archibald, Frederick and Eliza Frances Catherine. Both sons became distinguished officers.

SIR ARCHIBALD ALISON, Bart. (1826-1907), the elder of the sons, entered the 72nd Highlanders in 1846. He served at the siege of Sevastopol; and during the Indian Mutiny he was military secretary to Sir Colin Campbell and was severely wounded at the relief of Lucknow, losing an arm. From 1862 to 1873 he was assistant adjutant-general at headquarters, Portsmouth and Aldershot. He was second in command of the Ashanti expedition 1873-1874, and was made a K.C.B. For three years Alison was deputy adjutant-general in Ireland, and then, for a few months, commandant of the Staff College. He was promoted to be major-general in 1877, and was head of the intelligence branch of the war office (1878-1882). He commanded the troops at Alexandria in 1882 until the arrival of Sir Garnet Wolseley, led the Highland brigade at the battle of Tel-el-Kebir, and remained in command of the army of occupation until 1883. He commanded at Aldershot 1883-1888, was for some months adjutant-general to the forces during Lord Wolseley's absence in Egypt, was made G.C.B. in 1887, was promoted general, and became a military member of the Council of India in 1889. He retired in 1893 and died in 1907.

ALIWAL, a village of British India, in the Ludhiana district of the Punjab, situated on the left bank of the Sutlej, and famous as the scene of one of the great battles of the 1st Sikh War. Late in January 1846 it was held by Ranjur Singh, who had crossed the river in force and threatened Ludhiana. On the 28th Sir Harry Smith, with a view to clearing the left or British bank, attacked him, and after a desperate struggle thrice pierced the Sikh troops with his cavalry, and pushed them into the river, where large numbers perished, leaving 67 guns to the victors. The consequence of the victory was the submission of the whole territory east of the Sutlej to the British.

ALIWAL NORTH, a town of South Africa, on the south bank of the Orange River, 4300 ft. above the sea, and 282 m. by rail N.W. by N. of the port of East London. Pop. (1904) 5566, of whom 1758 were whites. The town, a trading and agricultural centre for the N.E. part of the Cape and the neighbouring regions of Basutoland and Orange Free State, presents a pleasing appearance. It contains many fine stone buildings. The streets are lined with trees, and water from the neighbouring sulphur springs flows along them in open channels. The river, here the boundary between the Cape province and Orange Free State, is crossed by a stone bridge 860 ft. long. The sulphur springs, 1 m. from the town, which yield over 500,000 gallons daily, are resorted to for the cure of rheumatism and skin diseases. By reason of its dry and bracing climate, Aliwal North is also a favourite residence of sufferers from chest complaints. In the neighbourhood are stone quarries. Aliwal North is the capital of a division of the province of the same name, with an area of 1330 sq. m. and a pop. (1904) of 14,857, of whom 40% are whites.

Aliwal North was so called to distinguish it from Aliwal South, now Mossel Bay, the seaport of the pastoral Grasveld district, on the west side of Mossel Bay. Both places were named in honour of Sir Harry Smith, governor of Cape Colony 1847-1852, Aliwal (see above) being the village in the Punjab where in 1846 he gained a great Victory over the Sikhs. Crossing the Orange River at this spot in September 1848, Sir Harry noted that it was ``a beautiful site for a town,'' and in the May following the town was founded. In the early months of the Boer War of 1899-1902 Aliwal North was held by the Boers. It was reoccupied by the British in March 1900.

ALIZARIN, or 1.2 DIOXYANTHRAQUINONE,

/CO\ C6H4 C6H2(OH)2[1.2], \CO/ a vegetable dyestuff formerly prepared from madder root (Rubia tinctorum) which contains a glucoside ruberythric acid (C26H28O14). This glucoside is readily hydrolysed by acids or ferments, breaking up into alizarin and glucose:

C26H28O14 + 2H2O = 2C6H12O6 + C14H8O4 Ruberythric acid = Glucose + Alizarin. Alizarin was known to the ancients, and until 1868 was obtained entirely from madder root. The first step in the synthetical production of alizarin was the discovery in 1868 of C. Graebe and C. Liebermann that on heating with zinc dust, alizarin was converted into anthracene. In order to synthesize alizarin, they converted anthracene into anthraquinone and then brominated the quinone. The dibrominated product so obtained was then fused with caustic potash, the melt dissolved in water, and on the addition of hydrochloric acid to the solution, alizarin was precipitated. This process, owing to its expensive nature, was not in use very long, being superseded by another, discovered simultaneously by the above-named chemists and by Sir W. H. Perkin; the method being to sulphonate anthraquinone, and then to convert the sulphonic acid into its sodium salt and fuse this with caustic soda.

In practice, the crude anthracene is purified by solution in the higher pyridine bases, after which treatment it is frequently sublimed. It is then oxidized to anthraquinone by means of sodium dichromate and sulphuric acid in leaden vats, steam heated so that the mixture can be brought to the boil. When oxidation is complete the crude anthraquinone is separated in filter presses and heated with an excess of commercial oil of vitriol to 120 deg. C., the various impurities present in the crude material being sulphonated and rendered soluble in water, whilst the anthraquinone is unaffected; it is then washed, to remove impurities, and dried. The anthraquinone so obtained is then heated for some hours at about 150-160 deg. C. with fuming sulphuric acid (containing about 40-50% SO3), and by this treatment is converted into anthraquinone-b-monosulphonic acid. The solution is poured into water and sodium carbonate is added to neutralize the excess of acid, when the sodium salt of the monosulphonic acid (known as silver salt) separates out This is filtered, washed, and then fused with caustic soda, when the sulpho-group is replaced by a hydroxyl group, and a second hydroxyl group is simultaneously formed; in order to render the formation of this second group easier, a little potassium chlorate or sodium nitrate is added to the reaction mixture. The melt is dissolved in water and the dyestuff is liberated from the sodium salt by hydrochloric or sulphuric acid, or is converted into the calcium salt by digestion with hot milk of lime, then filtered and the calcium salt decomposed by acid. The precipitated alizarin is then well washed and made into a paste with water, in which form it is put on to the market.

K. Lagodzinski (Berichte, 1895, 28, p. 1427) has synthesized alizarin by condensing hemipinic acid [(CH3O)2C6H2(COOH)2] with benzene in the presence of aluminium chloride. The product on acidification gives a compound C15H12O5.H2O which is probably an oxy-methoxy-benzoyl benzoic acid. This is dissolved in cold concentrated sulphuric acid, in which it forms a yellowish red solution, but on heating to 100 deg. C. the colour changes to red and violet, and on pouring out upon ice, the monomethyl ether of alizarin is precipitated. This compound is hydrolysed by hydriodic acid and alizarin is obtained. It can also be synthesized by heating catechol with phthalic anhydride and sulphuric acid at 150 deg. C.

/CO\ /CO\
C6H4 O + C6H4(OH)2[1.2] = H2O + C6H4 C6H2(OH)2.
\CO/ \CO/

Pure alizarin crystallizes in red prisms melting at 200 deg. C. It is insoluble in water, and not very soluble in alcohol. It dissolves readily in caustic alkalis on account of its phenolic character, and it forms a yellow-coloured di-acetate. Its value as a dyestuff depends on its power of forming insoluble compounds (lakes) with metallic oxides. It has no affinity for vegetable fibres, and consequently cotton goods must be mordanted before dyeing with it (see DYEING.)

Numerous derivatives of alizarin are known. On solution in glacial acetic acid and addition of nitric acid, b-nitroalizarin

OH
|
(alizarin orange) / \ /CO\ / \OH
| | | |
\ / \CO/ \ /NO2

is produced, and this on heating with sulphuric acid and glycerin is converted into alizarin blue.

The trioxyanthraquinones--purpurin, anthrapurpurin, anthragallol and flavopurpurin---are also very valuable dyestuffs. These compounds may be represented by the following formulae:

OH OH OH OH
| | | |
/ \ /CO\ / \OH HO/ \ /CO\ / \OH / \ /CO\ / \OH / \ /CO\ / \OH
| | | | | | | | | | | | | | | |
\ / \CO/ \ / \ / \CO/ \ / HO\ / \CO/ \ / \ / \CO/ \ /OH
|
OH

Purpurin. Anthrapurpurin. Flavopurpurin. Anthragallol.

Purpurin (1.2.4 trioxyanthraquinone) is found with alizarin in madder root; it is now prepared synthetically by oxidizing alizarin with manganese dioxide and sulphuric acid. After the separation of the silver salt (see above) obtained on sulphonating anthraquinone, the remaining acid liquid gives on treatment with calcium carbonate the calcium salt of anthraquinone 2.6 disulphonic acid (anthraquinone- a-disulphonic acid). This is converted into the sodium salt by means of sodium carbonate, and on alkali fusion yields fiavopurpurin. In a similar manner anthrapurpurin is prepared by alkali fusion of anthraquinone 2.8 disulphonic acid. Anthragallol is synthetically prepared by the condensation of benzoic and gallic acids with sulphuric acid

OH OH
| |
/ \COOH / \OH / \ /CO\ / \OH
| | + | | = 2 H2O + | | | |
\ / HOOC\ /OH \ / \CO/ \ /OH

or from pyrogallol and phthalic anhydride in the presence of sulphuric acid or zinc chloride.

A. Baeyer in 1890, by heating alizarin with fuming sulphuric acid for 24-48 hours at 35-40 deg. C., obtained a product, which after treatment with caustic soda gave a sulphuric acid ester of quinalizarin, and this after acidification and boiling was converted into quinalizarin (Alizarin Bordeaux) or 1.2.6.9 tetra-oxyanthraquinone. Penta-oxyanthraquinones have been obtained from purpurin and anthrapurpurin, while a hexa- oxyanthraquinone has been obtained from 1.5 dinitro- anthraquinone.

ALKAHEST (a pseudo-Arabic word believed to have been invented by Paracelsus), a liquid, much sought after by the alchemists, having the power of dissolving gold and every other substance, which it was supposed would possess invaluable medicinal qualities.

ALKALI, an Arabic term originally applied to the ashes of plants, from which by lixiviation carbonate of soda was obtained in the case of sea-plants and carbonate of potash in that of land-plants. The method of making these ``mild'' alkalis into ``caustic'' alkalis by treatment with lime was practised in the time of Pliny in connexion with the manufacture of soap, and it was also known that the ashes of shore-plants yielded a hard soap and those of land-plants a soft one. But the two substances were generally confounded as ``fixed alkali'' (carbonate of ammonia being ``volatile alkali''), till Duhamel du Monceau in 1736 established the fact that common salt and the ashes of sea-plants contain the same base as is found in natural deposits of soda salts (``mineral alkali''), and that this body is different from the ``vegetable alkali'' obtained by incinerating land- plants or wood (pot-ashes). Later, Martin Heinrich Klaproth, finding vegetable alkali in certain minerals, such as leucite, proposed to distinguish it as potash, and at the same time assigned to the mineral alkali the name natron, which survives in the symbol, Na, now used for sodium. The word alkali supplied the symbol for potassium, K (kalium.) In modern chemistry alkali is a general term used for compounds which have the property of neutralizing acids, and is applied more particularly to the highly soluble hydrates of sodium and potassium and of the three rarer ``alkali metals,'' caesium, rubidium and lithium, also to aqueous ammonia. In a smaller degree these alkaline properties are shared by the less soluble hydrates of the ``metals of the alkaline earths,'' calcium, barium and strontium, and by thallium hydrate. An alkali is distinguished from an acid or neutral substance by its action on litmus, turmeric and other indicators.

ALKALI MANUFACTURE. The word ``alkali'' denotes both soda and potash, but by ``alkali manufacture'' we understand merely the manufacture of sodium sulphate, carbonate and hydrate. The corresponding potash compounds are not manufactured in the United Kingdom, but exclusively in Germany (from potassium chloride and from the mother-liquor of the strontia process in the manufacture of beetroot sugar) and in France (from vinasse) . The term alkali is employed in a technical sense for the carbonate and hydrate (of sodium), but since in the Leblanc process the manufacture of sodium sulphate necessarily precedes that of the carbonate, we include this as well as the manufacture of hydrochloric acid which is inseparable from it. We also treat of the utilization of hydrochloric acid for the manufacture of chlorine and its derivatives, which are usually comprised within the meaning of the term ``alkali manufacture.'' A great many processes have been proposed for the manufacture of alkali from various materials, but none of these has become of any practical importance except those which start from sodium chloride (common salt); and among the latter again only three classes of processes are actually employed for manufacturing purposes, viz. the Leblanc, the ammonia-soda, and the electrolytic processes.

I. THE LEBLANC PROCESS

The Leblanc process, which was invented by Nicolas Leblanc (q.v.) about 1790, begins with the decomposition of sodium chloride by sulphuric acid, by which sodium sulphate and hydrochloric acid are produced. The sodium sulphate is afterwards fluxed with calcium carbonate and coal, and a mixture is thus obtained from which sodium carbonate can be extracted by exhausting it with water.

Leblanc himself for a time carried out his process on a manufacturing scale, but he was ruined in the political troubles of the time and died by his own hand in 1806. His invention was, however, at once utilized by others in France; and in Great Britain, after a few previous attempts on a small scale, it was definitely introduced by James Muspratt (q.v.) in 1823. From that time onward the Leblanc process spread more and more, and for a considerable period nearly all the alkali of commerce was made by it. The rise of the ammonia-soda process (since 1870) gradually told upon the Leblanc process, which in consequence has been greatly restricted in Great Britain and Germany, and has become practically extinct in all other countries, except as far as its first part, the manufacture of sodium sulphate and hydrochloric acid, is concerned.

The production of alkali in Great Britain, soon after the introduction of the Leblanc process, became the most extensive in the world, and outstripped that of all other countries put together. With the rise of the ammonia-soda process, for which the economic conditions are nearly as favourable in other countries, the predominance of Great Britain in that domain has become less, but even now that country produces more alkali than any other single country. Most of the British alkali works are situated in South Lancashire and the adjoining part of Cheshire, near the mouth of the Tyne and in the West of Scotland.

Various industries are carried on in Leblanc alkali works, as follows:--

1. Manufacture of sodium sulphate.

2. Manufacture of hydrochloric acid.

3. Preparation of chlorine.

4. Employment of chlorine for the manufacture of bleaching- powder and of chlorates.

5. Manufacture of ordinary alkali from sulphate of soda.

6. Manufacture of caustic soda.

7. Manufacture of soda crystals.

8. Recovery of sulphur from alkali waste.

1. Manufacture of Sodium Sulphate.--This is commercially known as salt-cake, and is made by decomposing common salt with sulphuric acid of about 80%, the reaction being 2NaCl + H2SO4 = Na2SO4 + 2HCl. This reaction proceeds in two stages. At first principally acid sodium sulphate, NaHSO4, is formed together with some normal sulphate; later, when the temperature has risen, the NaHSO4 acts with more NaCl so that nearly all of it is converted into Na2SO4. The gaseous hydrochloric acid evolved during all this time must be absorbed in water, unless it is directly converted into chlorine (see below, 2 and 3).

The process is carried out either in hand-wrought furnaces, or mechanical furnaces, both called ``decomposing'' or ``salt-cake furnaces.'' In the former case, the first reaction is produced in cast- iron pans or ``pots,'' very heavy castings of circular section, fired from below, either directly or by the waste heat from the muffle- furnace. The reaction is completed in a ``roasting- furnace.'' The latter was formerly often constructed as a revereratory funace, which is easy to build and to work, but the hydrochloric acid given off here, being mixed with the products of the combustion of fuel, cannot be condensed to strong acid and is partly, if not entirely, wasted. It is, therefore, decidedly preferable to employ ``muffle-furnaces'' in which the heating is performed from without, the fire-gases passing first over the arch and then under the bottom of the muffle. This requires more time and fuel than the work in ``open'' furnaces, but in the muffles the gaseous hydrochloric acid is separated from the fire-gases, just like that evolved in the pot, and can therefore be condensed into strong hydrochloric acid, like the pot-acid. This roaster-acid is, however, of less value than the pot-acid, as it contains more impurities.

It is not easy to keep the muffles permanently tight, and as soon as any leakages occur, either hydrochloric acid must escape into the fire-flue, or some fire-gases must enter into the muffle. The former is decidedly more objectionable than the latter, as it means that uncondensed hydrochloric acid is sent into the air. This drawback has been overcome by the construction of ``plus-pressure'' furnaces (figs. 1 and 2), where the fire-grate is placed 11 ft. below the top of the muffle. In consequence the fire-gases, when arriving there by the chimney shaft (a), have already a good upward draught, and when circulatung round the muffle are at a lower pressure than the gases within the muffle, so that in case of any cracks being formed, no hydrochloric acid escapes into the fire-flues, but vice versa.

Since the work with ordinary hand-wrought salt-cake furnaces is disagreeable and costly, many attempts have been made to construct mechanical salt-cake furnaces. Of these J. Mactear's furnaces (fig. 3) have met with the greatest success. They consist of a horizontal pan, 17 ft. wide, which is made up of a central pan (e), and a series of concentric compartments (C1), (C2), (C3), and which is supported on a frame (d d), revolving round a perpendicular axis on the wheels (n n). It is with an arch and heated on the top from one side (l), either by an ordinary coal-grate or by a gas-producer. A set of stirring blades carried in the frame (b b), and driven by gearing,

FIGS. 1. and 2.--Salt-cake Furnace. (Sectional Elevation and Plan.) Scale

Figs. 1-9 from Lunge's Handbuch der Soda-Industrie, by permission of Friedr. Vieweg u. Sohn.

passes through a gap in the arch in such a manner that the gases cannot escape outwards. The salt is conveyed to the furnace by a chain of buckets running on the pulley (g), and passing into the hopper (h), and through the pipe (i) is mixed with the proper amount of acid supplied by the pipe ( f.) The mixture is fed in continuously to the central pan (e.) whence it overflows into the compartments (c1), (c2), (c3) successively until it reaches the circumference, where it is discharged continously by o and p into the collecting-box (q), being now converted into salt-cake. This furnace acts very well, and has been widely introduced both in Great Britain and in other countries, but it has one great drawback, apart from its high cost, viz. that all the hydrochloric acid gas gets mixed with fire-gases, and consequently is condensed in a weaker and less pure form than from ordinary pots and muffles. This has led some factories which had introduced such furnaces to revert to hand-wrought muffle-furnaces.

Much was expected at one time from the.``direct salt-cake process'' of Hargreaves and Robinson, in which common salt is subjected in a series of large cast-iron cylinders to the action of pyrites-burner gases and steam at a low red heat. The reaction going on here is: 2NaCl + SO2 + O + H2O = Na2SO4 + 2HCl. This means that the previous manufacture of sulphuric acid in the vitriol-chambers is done away with, but this apparently great simplification is balanced by the great cost of the Hargreaves plant, and by the fact that the whole of the hydrochloric acid is mixed with nine or ten times its volume of inert gases. Owing to this, it is practically impossible to condense the gaseous hydrochloric acid into the commercial acid, although this acid may be obtained sufficiently strong to be worked up in the Weldon chlorine process (see below, 3). Therefore the Hargreaves process has been introduced only in a few places.

Although the consumption of salt-cake for the manufacture of alkali is now much less than formerly, since the Leblanc alkali process has been greatly restricted, yet it is largely made and will continue to be made for the use of glassmakers, who use it for the ordinary description of glass in the place of soda-ash. Nor must it be overlooked that salt-cake must be made as long

FIG. 3.--Mechanical Salt-cake Furnace. (Sectional Elevation.) Scale

as there is a sale for hydrochloric acid, or a consumption of the latter for the manufacture of chlorine.

2. Manufacture of Hydrochloric Acid (commercially also known as ``muriatic acid''). This unavoidable gaseous bye-product of the manufacture of salt-cake was, during the first part of the 19th century, simply sent into the air. When its deleterious effects upon vegetation, building materials, &c., became better known, and when at the same time an outlet had been found for moderate quantities of hydrochloric acid, most factories made more or less successful attempts to ``condense'' the gas by absorption in water. But this was hardly anywhere done to the fullest possible extent, and in those districts where a number of alkali works were located at no great distance from one another, their aggregate escapes of hydrochloric and other acids created an intolerable nuisance. This was most notably the case in South Lancashire, and it led to the passing of Lord Derby's ``Alkali Act,'' in 1863, supplemented by further legislation in 1874, 1881 and later. There is hardly another example in the annals of legislative efforts equal to this, in respect of the real benefit conferred by it both on the general public and on the manufacturers themselves. This is principally the consequence of the exemplary way in which the duties of inspector under these acts were carried out by Dr R. Angus Smith (1817-1884) and his successors, who directed their efforts not merely to their primary duty of preventing nuisance, but quite as much to showing manufacturers how to make the most of the acid formerly wasted in one shape or another. Not merely Great Britain but all mankind has been immensely benefited by the labours of the British alkali inspectors, which were, of course, supplemented by the work of technical men in all the countries concerned. The scientific and technical principles of the condensation of hydrochloric acid are now thoroughly well understood, and it is possible to recover nearly the whole of it in the state of strong commercial acid, containing from 32 to 36% of pure hydrochloric acid, although probably the majority of the manufacturers are still content to obtain part of the acid in a weaker state, merely to satisfy the requirements of the law prescribing the prevention of nuisance. The principles of the condensation, that is of converting the gaseous hydrochloric acid given off during the decomposition of common salt into a strong solution of this gas in water, can be summarized in a few words. The hydrochloric acid gas, which is always diluted with air, sometimes to a very great extent, must be brought into the most intimate contact possible with water, which greedily absorbs it, forming ordinary hydrochloric acid, and this process must be carried so far that scarcely any hydrochloric acid remains in the escaping gases. The maximum escape allowed by thc Alkali Acts, viz. 5 % of the total hydrochloric acid, is far above that which is now practically attained. For a proper utilization of the condensed acid it is nearly always imperative that it should be as strong as possible, and this forms a second important consideration in the construction of the condensing apparatus. Since the solubility of hydrochloric acid in water decreases with the increase of the temperature, it is necessary to keep the latter down--a task which is rendered somewhat difficult both by the original heat retained by the gases on their escape from the decomposing apparatus, and by the heat given off through the reaction of hydrochloric acid upon water.

Very different methods have been employed to effect all the above purposes. In Great Britain Gay-Lussac's coke-towers, adapted by W. Gossage to the condensation of hydrochloric acid, are still nearly everywhere in use, frequently combined with a number of stone tanks through which the gas from the furnaces travels before entering the towers, meeting on its way the acid condensed in the tower. This process is excellent for effecting a complete condensation of the hydrochloric acid as prescribed by the Alkali Acts, and for recovering the bulk of the acid in a tolerably strong state, but less so for recovering nearly the whole of it in the most concentrated state, although even this is occasionally attained. On the continent of Europe, where the last-named requirement has been for a long time more urgent than in Great Britain, another system has been generally preferred, namely, passing the gas through a long series of stoneware receivers, and ultimately through a small tower packed with stoneware or coke, making the acid flow in the opposite direction to the gas. Great success has also been obtained by ``plate-towers'' made of stoneware, which allow both the coke-towers and most of the stoneware receivers to be dispensed with.

3. Preparation of Chlorine.--In this place we speak only of the preparation of chlorine from hydrochloric acid by chemical processes; the electrolytic processes will be treated hereafter. It is clear that free chlorine must be prepared from hydrochloric acid by oxidizing the hydrogen. This can be done most easily by ``active'' oxygen, such as is present in the peroxides, in chromic or permanganic acid. Practically the only agent employed in this way, and that already by C. W. Scheele, the discoverer of chlorine, in 1774, is the peroxide of manganese (manganese dioxide), found in considerable quantities in nature as ``manganese ore'' (the purest of which is called pyrolusite), and also artificially regenerated from the waste liquors of a former operation. Even now, where chlorine is required for immediate use in some other chemical operations on a comparatively small scale, it is obtained by the action of hydrochloric acid on native manganese dioxide, according to the equation: Mno2 + 4HCl = MnCl2 + Cl2 + 2H2O. This action must be promoted by heating the mixture, but even then nothing like all of the hydrochloric acid employed is made to act as above, because the attack on the manganese ore requires a certain minimum concentration of the acid. Formerly, instead of free hydrochloric acid a mixture of common salt and sulphuric acid was sometimes employed, but this is never done on a manufacturing scale now. Owing to the impossibility of employing any metal in contact with the acid, the ``chlorine stills,'' where the above reaction is carried out, must be made of acid-proof stones or ``chemical'' stoneware. This process is very costly, as much of the acid and all of the manganese is wasted. Moreover it is of a most disagreeable kind, as the waste ``still-liquor,'' containing very much free hydrochloric acid and even some free chlorine, forms a most deleterious impurity when finding its way into drains or water- courses, apart from the intolerable nuisance caused by the escapes of chlorine from the stills and otherwise, which cannot be at all times avoided.

Many endeavours were made to avoid the loss of the manganese in this operation, but with only partial or no success. The difficulty was only overcome by the Weldon process, being the inventions of Walter Weldon from 1866 onwards, and his process up to this day furnishes the greater proportion of chlorine manufactured in the world. It begins with ``still-liquor,'' obtained in the old way from native manganese ore and hydrochloric acid. This liquor is first treated with carbonate of lime (ground chalk or limestone) in a ``neutralizing-well,'' made of acid-proof material and provided with wooden stirring-gear. Here the free hydrochloric acid is converted into calcium chloride, and at the same time any ferric chloride present is converted into insoluble ferric hydroxide: 2FeCl3 + 3CaCO3 + 3 H2O = 2Fe(OH)3 + 3CaCl2 + 3CO2. The sulphuric acid present is mostly precipitated as calcium sulphate. The mud thus formed is settled out, and the clear liquor, which is now quite neutral and contains both manganese and calcium chlorides, is mixed with cream of lime and treated by a strong current of air, produced by a blowing-engine. This is done in a tall iron cylinder, say 9 ft. wide and 30 ft. high, called the ``oxidizer.'' The air-pipe goes right to the bottom of the cylinder and there branches out into perforated side-pipes, so that the mass is thoroughly stirred up all the time. The first action of the lime is to convert the manganese chloride into manganous hydrate (Mn(OH)2) and calcium chloride; then more lime is added which greatly promotes and hastens the oxidizing process. The object of the latter is to convert the manganous hydroxide by the atmospheric oxygen into manganese dioxide, but this would take place much too slowly if there was not an excess of lime present ready to combine with the manganese dioxide to form a calcium manganite. Only so much lime is used that an acid manganite is formed corresponding to one molecule of calcium oxide to two of manganous oxide. This additional lime, which is called the ``basis,'' certainly takes up hydrochloric acid in the next stage of the process, but that causes no more waste of acid than the incomplete action on native manganese ore, mentioned before. The product obtained, called ``Weldon mud,'' is of such fine texture that it acts immediately with hydrochloric acid when mixed with it in the ``Weldon stills'' (fig. 4), and that this acid can be almost entirely neutralized thereby. The new still liquor formed in this manner is treated as above, so that the manganese does its work over and over again. There is only a slight mechanical loss, which is reduced in the best managed works to about 2 parts of manganese dioxide to 100 of bleaching- powder. There are also other advantages of this process which explain its wide extension, in spite of the fact that only from 30 to 35 parts of the hydrochloric acid employed is converted into chlorine, the remainder ultimately leaving the factory in the shape of a harmless but useless solution of calcium chloride.

Weldon's later attempts at superseding his classical process by other inventions which utilize a larger proportion of the chlorine, introduced as hydrochloric acid, have not been successful in the long run, although some of them were aided by the great technical skill of A. R. Pechiney. But the Deacon process, the invention of Henry Deacon (who was greatly aided by his chemist Dr Ferdinand Hurter), carried out since 1868, has attained to better, although nothing like complete, success in that direction.

The Deacon process, like the Weldon process, effects its object by the oxidizing action of atmospheric air, but in a very different manner. Weldon retained the principle of the Scheele

FIG. 4.--Weldon Chlorine Still. (Sectional Elevation.) Scale

C, Stone steam column resting in stone socket K.

process by employing the active oxygen of manganese dioxide to convert hydrochloric acid into free chlorine, and he employed the atmospheric oxygen only indirectly, for the recovery of manganese dioxide from the manganese chloride formed. But Deacon worked on the direct reaction: 2HCl + O = H2O + Cl2. This reaction in ordinary circumstances is so slow as to be practically useless. If, however, a ``contact-substance'' is employed and that at the proper temperature, the process goes on at an immensely quickened rate and can even be carried out as a continuous operation. The only substance which possesses sufficiently strong catalytic properties for the reaction is cupric chloride. If pieces of porous clay are soaked in a solution of this salt and dried and kept at a temperature of 450 deg. C. (in practice it is necessary to go to a rather higher temperature), it is possible continuously to convert a united stream of hydrochloric acid and atmospheric air, passed through the contact- substance in a ``decomposer'' (fig. 5), to a larger extent into chlorine and water, of course mixed with the excess of oxygen and all the nitrogen of the air. On a small scale it is possible to push the decomposition as far as 90% of the hydrochloric acid, but on the large scale only at most 60% is reached. The mixture of hydrochloric acid and air is taken directly from the ``decomposing-pan'' of an ordinary salt-cake furnace, is first cooled down in pipes sufficiently to condense most of the moisture present (together with about 8% of the hydrochloric acid), and then passed through a cast-iron superheater and from this into the ``decomposer.'' The gaseous mixture, issuing from the latter, is washed with water in the usual condensing apparatus, to remove the 40 or 50 parts of hydrochloric acid left unchanged, and can then be immediately employed for the manufacture of chlorate of potash.

Where (as is the more usual case) the chlorine has to serve for the manufacture of bleaching-powder, it must first be deprived of the great amount of moisture which it contains, by means of

FIG. 5.--Deacon ``Decomposer.'' (Sectional Elevation.) Scale 1/40. a,a, Upright cast-iron cylinders; b,b, brick jacket; c,c, flues; d,e, iron plates arranged like venetian blinds, between which the contact-substance is contained; f, charging hole; g, discharging hole; h, entrance pipe for gas; i, exit pipe for gas.

coke-towers fed with moderately strong sulphuric acid. As the gas issuing from these contains only about 5 volumes % of hydrochloric acid, it cannot be made to act upon lime in the ordinary bleaching-powder chambers, but specially constructed chambers must be provided (see fig. 4). The movement of the gases through all this complicated set of apparatus is produced by a Root's blower placed at the end of it all.

The Deacon process makes cheaper chlorine than the Weldon process, but the plant is complicated and costly and the working requires a great deal of attention. In skilled hands it has been proved to yield excellent results.

The hydrochloric acid from the calcining-furnaces or ``roasters'' cannot be employed immediately for the Deacon process, as the sulphuric acid always contained in the roaster gases soon ``poisons'' the contact-substance and renders it inoperative. This acid must, therefore, be condensed in the ordinary way into liquid hydrochloric acid and formerly could be worked up only by the Weldon process. R. Hasenclever has overcome this drawback by running this impure acid into moderately strong sulphuric acid (140 deg. Twaddell), blowing in air at the same time. This produces a mixed current of pure hydrochloric acid gas and air, which is carried into a Deacon decomposer where it acts in the usual manner. The sulphuric acid, of which 6 or 7 parts are used to one of impure liquid hydrochloric acid, is always reserved for use in the same process, by driving off the excess of water in a lead pan, fired from the top, so that the principal expense of the process is that of the fuel required for the last operation.

4. Applications of Chlorine.--Some of the chlorine manufactured (practically only such as is obtained by the electrolysis of chlorides) is condensed by cold and pressure into liquid chlorine. If this is anhydrous, as it must be in any case for this purpose, it does not act upon the metal of the compressors, nor upon the iron bottles in which it is sent out. It may even be sent out in tank wagons, similar to those which are employed for carrying sulphuric acid, holding 10 tons each.

Sometimes the chlorine is employed directly for bleaching purposes, especially for some kinds of paper. A number of organic chlorinated products are also produced on a large scale. But most of the chlorine is utilized for the production of bleaching- powder, of bleach-liquor, and of chlorate of potash.

Bleaching-powder is a compound obtained by the action of free chlorine on hydrated lime, containing a slight excess of water at ordinary temperatures or slightly above these. Its composition approaches the formula CaOCl2, and it is regarded as a double salt of calcium chloride and hypochlorite, which by the action of water splits up into a mixture of these salts. It always contains a certain quantity of chemically combined water and also an excess of lime. Usually this lime is regarded only as mechanically mixed with the bleaching-compound, CaOCl2, but some chemists adopt formulae in which this lime is equally represented.

For the manufacture of bleaching-powder, limestone of high degree of purity (especially free from magnesia and iron) is carefully burned so as to drive out nearly all the carbon dioxide without overheating the lime. The quick-lime is then slaked with the requisite quantity of water; the product is passed through a fine-meshed wire sieve and is spread in layers of 2 or 3 in. at the bottom of large boxes, the ``bleaching-powder chambers,'' made of lead, or sometimes of cast-iron protected by paint, of slate or even of tarred wood. Chlorine, generated in an ordinary or a Weldon still, is passed in and is rapidly absorbed. When the absorption becomes slow, the gas is cut off and the chamber is left to itself for twelve hours or more, when it will be found that all the chlorine has been taken up. Now the door of the chamber is opened, the powder lying at the bottom is turned over and the treatment with gas is repeated. Sometimes a third treatment is necessary in order to get the product up to the strength required in commerce, viz. 35% of ``available'' chlorine. The finished product is packed into wooden casks lined with brown paper. The work of packing is a most disagreeable and unhealthy operation which is best relieved by erecting the chambers at a higher level and placing the casks underneath, communication being made by means of traps in the chamber-bottom. so that the packers can do their work outside the chambers. The bleaching-powder casks must be kept in a dry place, as cool as possible, and never exposed to the direct rays of the sun, in order to prevent a decomposition which now and then has even led to explosions.

The weak chlorine from the Deacon process cannot be treated in this manner, as chambers of impossibly large dimensions would be required. Originally the absorption of the Deacon chlorine took place in a set of chambers, constructed of large slabs of stone, containing a great many horizontal shelves superposed over one another. About sixteen such chambers were combined in such manner that the fresh gas passed into that chamber which had been the longest time at work and in which the bleaching-powder was nearly finished, and so forth until the gas, now all but entirely exhausted, reached the last-filled chamber in which it met with fresh lime and there gave up the last of the chlorine. These ``Deacon chambers'' occupied a large space, besides being expensive to build and difficult to keep in repair.