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becoming jealous of his abilities, formed an ale son Nazir Jung, whose cause was espoused by liance with the Mahrattas and the nizam of the the English, and his grandson Mirzapha Jung, Deccan against him; but Hyder not only gained who was favored by the French. The latter over the nizam to his side, but for two years finally triumphed, and governed under the diwaged vehement war on the British. By a se- rection of the French commander Dupleix until ries of skilful manoeuvres he managed to draw he was put to death by some Patan chiefs. their force to a distance from Madras, and then During a period of anarchy which followed, the at the head of 6,000 horsemen rode 120 m. in French and English supported rival claimants 3 days and appeared before the city. The out for the sovereignty. Nizam Ali, who came to lying country being at his mercy, the govern- the throne in 1761, ravaged the Carnatic, but ment of the presidency was disposed to come was overpowered by a British force, and into terms, and Hyder agreed to a treaty of which duced to sign a treaty in 1766 which gave to the principal feature was that the British should the East India company the Northern Circars. form an offensive alliance with him in his de- The English bound themselves to maintain a fensive wars. In 1770, the Mahrattas having military force for the nizam's protection. In invaded his dominions, he applied to the British the war between the British and Hyder Ali, for their promised aid, but could obtain from however, the nizam sided with the sultan of them nothing more than neutrality. By the Mysore, but in that with Tippoo Sultan he year 1778 he had recovered from the disadvan- formed an alliance with the company and the tages their defection had caused him. Being peishwa, and received a share of the spoils of once more threatened by the same warlike peo- victory. The accession of territory which he ple, he again invited British assistance, but then obtained he subsequently ceded to the with a like result. Incensed by this conduct, British in lieu of payment for the support of he formed an alliance with the Mahrattas and the British contingent. On the conclusion of the nizam, and in 1780 invaded the British ter- the first Mahratta war in 1804 his dominions ritory of the Carnatic, which he ravaged with were again enlarged. The misgovernment of fire and sword, capturing many of the strong the country under the successors of Nizam Ali places, but avoiding battle in the open field. plunged Hyderabad deeply in debt. The East The desolation he brought on the country dur. India company was at one time creditor to the ing the two years' war was such that the Brit- amount of £500,000 or £600,000, and in liquiish force, and even the city of Madras, were in dation they accepted a cession of territory, part danger from famine. This war elicited a re- of the revenues of which were to be devoted markable display of military talent by the Brit to the support of the subsidiary native force ish general Sir Eyre Coote on the one side, and known as the nizam's contingent. The nizam by Hyder and the French officers, of whom he remained true to the British during the mutiny had many in his service, on the other. The of 1857-'8, and his dominions were little disMysore leader had already rejected terms of turbed except by marauders. The present ni. adjustment offered by Lord Macartney, the goy. Zam, Afzul-ud-Dowlah, succeeded to the throne ernor of Madras, when he died, and was suc- on the death of his father, May 19, 1857.ceeded by his son Tippoo Sultan.

HYDERABAD, the capital of the above territory, HYDERABAD, or the NIZAM'S TERRITORY, is situated on the river Miessi, 389 m. N. W. a country of the Deccan, in Hindostan, bounded from Madras, 314 S. from Nagpoor, and 962 8. N. E. by Nagpoor, S. E. by the Madras presi- W. from Calcutta; pop. about 200,000, a large dency, W. and N. W. by the Bombay presiden- majority of whom are Mohammedans. It is a cy, and N. W. by Gwalior and the British dis- weakly fortified town, crowded with buildings, tricts of Sangor and Nerbudda; area, 95,337 some of which are large and imposing, having sq.m.; pop. estimated at 10,000,000. The sur- numerous mosques, and surrounded by gardens face consists chiefly of a high table-land watered of remarkable beauty. The British residency by the Godavery, Wurda, Kistnah, and several is a magnificent edifice on the opposite side of other rivers, fertile but not well cultivated. the river, connected with the town by a stone Wheat and cotton are the principal productions. bridge. In the neighborhood there are large The climate, owing to the elevated position of water tanks, one of which is 20 m. in circuit. the country, is colder than is usual in this lati- There is a large British military cantonment at tude. The territory is crossed by several good Secunderabad, a few miles N. from the town. military roads. The government is Mohamme- HYDRA. See HERCULES. dan, but the majority of the people are Hindoos. HYDRA, an island in the Grecian archipelHyderabad was anciently subject to the rajahs ago, off the E. coast of the Morea; greatest of Telingana and Bijanagur. It was erected length N. E. to S. W. about 12 m., greatest into a separate kingdom in 1512 by a Turkish breadth 3 m.; pop. about 20,000. Its surface is adventurer, and in 1687 became a province of rocky, sterile, and mountainous. The inhabithe Mogul empire. Azof Jah, an officer of the tants are esteemed the best sailors of Greece, court of Delhi, who in 1719 governed this and and rendered important services during the war the 5 other provinces of the Deccan with the of independence.-Hydra, the capital of the title of Nizam-ul-mulk (* regulator of the island, is situated on a barren rugged height state"), made himself independent. On his on the N. W. shore; pop. about 12,000. The death in 1748 the succession was disputed by his streets are steep and uneven, and the houses substantially built. The manufactures are silk and is attributed by Elliott to Georgia. It was and cotton stuffs, soap and leather. The harbor carried to England in 1803, and is considered is formed by a deep bay, but is neither spacious the finest of the North American species. It nor well sheltered. While the war of the revo- has deeply lobed, sinuate leaves, and fine large lution raged Hydra was a place of general ref- corymbs of nearly white flowers, which change uge for people from all parts of Greece.

afterward to purple. In the gardens at the HYDRABAD, a town of British India, in north is often seen the snowy-leaved hydrangea the province of Sinde, situated on an eminence (H. nivea, Mx.), a shrub from 6 to 8 feet high, belonging to the Gunjah hills, 4 m. E. from the with large leaves of a silvery whiteness beneath, E. bank of the Indus; pop. about 24,000. Part and flowers in terminal cymes, having a few of it is built on an island 15 m. long, which is showy, white sterile florets enclosing many formed by the Indus and an offset of that small green fertile ones. It grows naturally in stream called the Fulailee. It is defended the upper part of Georgia and the Carolinas. by a fortress of imposing appearance but no HYDRATES (Gr. úồwp, water), compounds great strength, and has manufactures of match- in which water is an ingredient in definite prolocks, swords, spears, and shields, and of orna- portion. Thus lime (oxide of calcium) slaked mental silks and cottons. The town is to be with water forms a chemical combination with connected with Kurrachee on the Arabian sea a portion of this, and falls to a white powder, by a railway 120 m. long, which was begun in which is a hydrate of lime (CaO, HO). HyApril, 1858. Hydrabad was formerly the resi- drate of potassa is a combination of one equivadence of the chief ameers of Sinde, who gov- lent of potassa and one of water, and is pererned the S. and principal part of the country. manent even when exposed to high temperature, A victory was gained over a Sindian force near Common oil of vitriol is also a chemical comhere by Sir O. Napier, Feb. 24, 1843.

bination of one equivalent of water and one of HYDRANGEA (Gr. údwp, water, and ayyos, pure concentrated sulphuric acid. a vase), a genus of shrubby plants, so called HYDRAULIC RÀM, or WATER Ray, a from their predilection for water, and from the machine first erected by John Whitehurst in calyx of some species resembling a cup, be- Cheshire in 1772, and improved by Montgolfier, longing to the natural order saxifragacea, and the object of which is to raise a small stream of natives of Asia and of North America. The spe- water to a considerable height by the power afcies best known by this naine (H. Hortensis) re- forded by a larger stream with little fall. The ceived the generic name of Hortensia from Com- main current is made to flow through a pipe from merson, and this name it still bears in France. the reservoir which feeds it, and which by its

The common hydrangea was brought to Enge elevation above the lower end of the pipe furland from China in the year 1790. Cuttings nishes the required power. An opening on the of the wood or of the growing stems will root upper side of the pipe at the lower end allows without difficulty ; those of the latter make the water to escape; but this opening is supplied roots soonest, and if they are then potted in with a valve, in the form of a hollow metallic rich soil, they will grow rapidly. The hy- ball, held within the pipe in a sort of claw didrangea delights in an unlimited supply of rectly under the opening. As the current acwater, fading at once on its being withheld. quires velocity this ball, twice as heavy as the There has lately been introduced into cultiva. water it displaces, is lifted up and shuts the ori. tion a variety with variegated foliage, nearly all fice of escape. Another similar but smaller valvo silvery white. In some parts of England the is placed on a short upright length of pipe & common hydrangea stands the winter, very little above the lower valve, and works in the severe weather only killing the stems to the opposite direction, closing the orifice by its roots. Specimens there are mentioned of 30 descent, and opening it as it is lifted up. This feet circumference, and producing on a single short pipe opens above into a strong metallic plant more than 1,000 heads or corymbs of chamber, which serves as a reservoir of water Howers. In the United States, even so far north in its lower part, and of air above. A tube, as Boston, it will survive the winter, if slightly called the ascension tube, leads from the water protected by the stems being covered. The Japan through the wall of the chamber to any place hydrangea (H. Japonica, Siebold), introduced required. The recoil of the water throws up into this country about 15 years ago, and into the valve and opens the passage into the chamEngland a short time previous, is considered in- ber, the action being facilitated by the spring ferior in both leaf and blossom. The wild hye produced by the pressure upon a body of air drangea (H. arborescens, Linn.) is a shrub having contained in an annular space surrounding the a stem 4 to 6 feet high with opposite branches, valve box, which is let a little way down into leaves 3 to 6 inches long, ovate, pointed, serrate, the short upright pipe to give room for this and green on both sides; its flowers, which are annular chamber. As the impulse fails which borne on flat cymes, are white or yellowish, opens the upper valve, the lower one is relieved and usually all fertile. The species ranges from of the pressure which lifted it and falls down, Pennsylvania and Ohio southward to the moun. opening the outlet, and the other also falls, clostains of Carolina. The oak-leaved hydrangea ing the orifice into the chamber, when the force (H. quercifolia) was first discovered by Bar- again accumulates, repeating the operation. tram in his travels through the southern states, With each stroke a quantity of water is injected into the large chamber. The air in the up- dwarfed, the contrast between the immense per part of this is each time compressed, and by head, the weight of which the child is unable its elasticity drives the water up the ascension to sustain, and the small and infantile face, gives tube, equalizing the effect of the strokes. Mont- the patient a strange and characteristic aspect. golfier was thus able with a head of 7 feet to More or less squinting or a constant rolling moraise to the height of 50 feet a quantity of wa- tion of the eyes is an attendant upon the disease. ter compared with the whole that flowed as 2 The intellect is weak, and the child is subject to 21, making the useful effect as 64 to 100 of to spasmodic attacks and convulsions; exhausthat expended; but it is more commonly about tion, diarrhea, or convulsions generally ter

of that expended. A uniform flow may be minate the patient's existence at an early age; obtained without the air chamber by using two in one instance, however, an extreme case, the or more rams, and connecting their ascension patient reached the age of 29 years. A variety tubes into one. Water has thus been raised at of remedial means have been recommended, but Marly in France to the height of 187 feet. The their effects are very uncertain, and the comyounger Montgolfier improved the ram so as to plaint when once fairly established may be obtain for it a useful effect of 60 per cent. The looked upon as hopeless.-Acute Hydrocephalus. changes introduced were in the form of the Dr. Whytt in 1768 was the first to call the atvalves, the lower one, of dish shape, being at- tention of the medical profession to the fact tached to a guide stem, which kept it in place as that in a large class of cases in young children, it worked up and down, and was so contrived evidently involving the brain and rapidly teras to give longer or shorter play to the valve as minating in death, the ventricles of the brain circumstances required. For the annular air were apt to be more or less distended by a space was substituted an air chamber of similar serous effusion; to this effusion the symptoms form to the large one, within which it was con- during life were attributed, and the disease was tained, and into which it opened by two valves. classed as a dropsy. Toward the commenceUnder it a capillary open tube connected with ment of the present century the inflammatory the air without, and with each stroke a jet of origin of the disease began to be recognized, water was forced out and air returned, the late and about the year 1830 the observations of MM. ter serving to keep up the supply required by Rufz and Gherard, at the hôpital des enfants, the air chambers. Its entrance was caused by proved the tubercular nature of by far the the reduced pressure within the smaller air greater number of cases. In consonance with chamber immediately after the elastic force had more correct views of its pathology, the disease expended itself, this pressure for an instant be- has accordingly been termed tubercular mecoming less than that of the air without. When ningitis. As would be anticipated, it is most the water is propelled by the ram to consider- apt to attack feeble and delicate children, esable height, its workings are so violent that the pecially those who have inherited a tendency ground is shaken, and the tremor is felt through to tubercular complaints; yet it often occurs in the whole length of the pipe. This destructive those who until its invasion have appeared to action is partially corrected by the improve- be in good health. In the beginning the child ments introduced in the rams constructed by is fretful and irritable, it loses its appetite, and Mr. Birkinbine of Philadelphia. In these the its movements are sluggish; the bowels are apt force of the blow of the larger valve as it rises to be constipated, the evacuations scanty and is received by a portion of water caught be- offensive, the skin dry, and the pulse acceltween the valve and its seat, which serves as a erated. If old enough, the child complains of water cushion. Some of the larger rams are headache, or it carries its hands to its head; worked by driving pipes of 6 inches diameter, it is unusually sensitive to light and noise; it and one of these with a fall of 6 feet is capable seems drowsy, but sleeps badly, starting and of raising 20,000 gallons per day 60 feet high grinding its teeth. Occasionally it appears for

HYDRAULICS. See HYDROMECHANICS. a few moments to lose its consciousness, gazing

HYDROCEPHALUS (Gr. údwp, water, and fixedly with its eyes wide open, and then sudKedaan, the head), dropsy of the brain. Chronic denly resuming its former manner. It is often hydrocephalus is commonly the result of either attacked with vomiting, which continues, witha malformation of the brain, or a chronic inflam- out apparent cause. After more or fewer of mation of the lining membrane of the ventricles. these symptoms of nervous disturbance have It is for the most part congenital, or shows itself continued for a variable number of days, the within a few weeks after birth, though it some- complaint becomes fully formed. The child retimes seems to have been caused by injuries mains in a drowsy condition, the eyes closed, the received on the head in early childhood.Con- brow contracted, and the countenance expresgenital hydrocephalus is occasionally an obsta- sive of suffering. It is averse to being disturb. cle to childbirth, the head requiring to be less- ed, answers shortly and quickly, and if old ened before it can be delivered with safety to enough complains only of its head and of weathe mother. When it occurs after birth, the riness. The skin remains hot and dry; the head gradually enlarges, assuming & globular pulse, at first more frequent, often suddenly form, the sutures and fontanelle becoming more becomes comparatively slow. At night there and more open. As the nutrition of the re- is an exacerbation of fever attended with restmainder of the body is imperfect and its growth lessness, and often with delirium. Sometimes the child continues to utter at intervals a short convulsions, which often recur until the death piercing cry characteristic of the disease. The of the patient; and its course is shorter, rarely bowels remain confined, and the evacuations lasting beyond a week. After death none of are scanty and unnatural, though the abdomen the granulations characteristic of tubercular is neither hard nor full; on the contrary, it is meningitis are found, but the serum effused in commonly retracted. The pupils are sometimes the ventricles is apt to be turbid, and pus is natural, and sometimes one is dilated while the sometimes found on the surface of the brain, other is contracted; they are apt to be sluggish The treatment must be prompt; leeches and to the influence of light, and squinting often cold to the head, active purgatives, and stimulatoccurs. Toward the close of the disease, the ing foot baths are recommended. child sometimes falls into a state of stupor, from HYDROCHLORIC ACID, or CIILOROHYDRIO which it cannot be roused; frequently convul- ACID, a gaseous compound of one equivalent of sions ensue, followed by paralysis of one side, chlorine and one of hydrogen (HCI), of combinwith automatic movements of the other. The ing proportion 36.5, long known in its aqueous child often picks at its nose, lips, or head, draw- solution by the names of muriatic acid, marine ing blood and leaving frightful-looking ulcera- salt, and spirit of salt, in reference to its being tions. The eyes remain constantly half open, prepared from sea salt (murias). Priestley first filmy, insensible to light, and commonly squint- obtained it as a gas in 1772, and Gay-Lussac, ing; the cheeks are now flushed, now pale; Thénard, and Davy long afterward showed that the head is often retracted; the pulse becomes it consists of equal volumes of chlorine and hyfeeble and exceedingly frequent, and the child drogen, and occupies the same space as the gases is more and more emaciated, until finally death which produce it. Its elements mixed together after a variable interval closes the scene. The slowly combine by the action of the light, but appearance after death to which for a long time instantly with explosion if exposed to the direct the attention of observers was confined is the rays of the sun, or if an electric spark is passed increased quantity of fluid in the ventricles; through the mixture, or a lighted taperis brought this varies greatly in different cases, and is in in contact with it. The gas is obtained by addgeneral perfectly transparent. The pia mater, ing concentrated sulphuric acid to common salt and more especially the arachnoid membrane, placed in a retort, and collecting over mercury. particularly at the base of the brain, present á The chlorine of the salt (chloride of sodium) milky or opaline appearance ; often more or less unites with the hydrogen of the water of the sulyellow lymph is found underneath the latter phuric acid, and the sodium, taking the oxygen of membrane. Beside these appearances, a number the water, forms with the sulphuric acid sulphate of minute granular bodies are found scattered of soda; or, by symbols, NaCl+SO, HO yields within the membranes, the largest of them being NaO, S03+HCI. The gas is colorless, but esof the size of a small pin's head; some of these caping in the air it instantly unites with moistbodies are yellowish and friable, others grayish, ure present, and forms a white cloud. It has a semi-transparent, and resistant. These bodies strongly acid taste and a pungent odor. Taken are always associated with the presence of tu- into the lungs it is irrespirable, but when dilutbercles in other organs of the body, and the ed with air is not so irritating as chlorine. It general opinion of pathologists is that they are neither supports combustion nor is itself inflamtubercular.—When the disease is recognized as mable. Under a pressure of 40 atmospheres, at tubercular meningitis, the prognosis is exceed- 50° F., it is condensed into a liquid of specific ingly unfavorable, the cases of cure on record gravity 1.27. The density of the gas is 1269.5, being few and doubtful. More can be done to air being 1000. Its affinity for water is such ward off the attack of the disease than to cure it that it can be kept only in jars over mercury. after its development. To this end, all efforts If a piece of ice be introduced into a jar containmust be directed toward strengthening the sys- ing the gas, the ice is instantly liquefied, and the tem of the child, and repressing undue activity gas disappears. If the jar be opened under w&of the brain or nervous system. In the com- ter, the water rushes up as into a vacuum. A mencement, and when the diagnosis is still un- cubic inch of water absorbs 418 cubic inches of certain, the employment of mild but efficient gas at 69°, and becomes 1.34 cubic inches. The purgatives seems to be indicated ; calomel with aqueous solution is the form in which the acid rhubarb and soda are among the most useful. is commonly known. It is of various degrees Occasionally the application of a few leeches of strength, the strongest readily obtained harto the head may be advisable, but the disease ing 6 equivalents of water to one of acid, 40.66 occurs mostly in children who bear depletion per cent. of real acid, and being of specific grar. badly. When the complaint is thoroughly es- ity 1.203. This loses acid by evaporation, comtablished, all measures seem to be of no avail; ing, according to Prof. Graham, to 12 equivastill a few cures are reported which appear to lents of water to one of acid, this containing 25.52 have been obtained by the employment of large of real acid, and being of specific gravity 1.1197. doses of iodide of potassium.--In rare instances When reduced by distillation till it changes no meningitis appears independently of a tubercular more, it contains 16.4 equivalents of water and origin. Here the disease occurs in children who 20 per cent. of real acid, and is of specific grayhave been previously healthy. It is more violent ity 1.0947. The following table by Mr. Ed. in its invasions, being commonly ushered in by Davy gives its strength at different densities :

... 101

6.00

1.11......

Quantity of

Quantity of of sulphuretted hydrogen. The common meth. Sp. gr. acid per cent. Sp. gr.

acid per cent, 1.21... 42.43 1.10.....

.. 20.20

od of purifying is to dilute, add chloride of 1.20.... 40.80 1.09....

18.18 barium, and distil.—The acid is largely em1.19.... 88.88 1.08.....

16.16

ployed in the arts, especially as a solvent for 1.18... 86.86 1.07...

14.14 1.17... 81.84 1.06....

12.12 mineral substances. In combination with nitric 1.16... 82.82 1.05....

acid it makes the aqua regia, used for dissolv1.15..

80.30
1.04...

8.03
1.14.
28.28 1.03....

ing gold and platinum. It is used to furnish 1.13. 26.26 1.02..

4.04 chlorine in the preparation of bleaching and 1.12... 24.24 1.01..

2.02

disinfectant salts, and in the production of sal 22.22

ammoniac.; and is employed to extract gelatine An approximate result is obtained by multiply- from bones. When neutralized with basic oxing the decimal of the specific gravity by 200.- ides, it does not combine as an acid with these, The pure concentrated acid is colorless, and but gives its hydrogen to their oxygen, and its fuming when exposed to the air. It is conve- chlorine unites with the metallic base of the niently used for most purposes diluted to a spe- oxide. In medicine the acid is employed as a cific gravity of about 1.1, at wbich it does not tonic, refrigerant, and antiseptic. The latter fume. Though powerfully acid, it is not so cor- quality recommends it as an adjunct to gargles rosive as sulphuric acid. It is decomposed by in ulcerated sore throat and scarlet fever. substances which yield oxygen freely, as the per- HYDROCYANIC ACID, or PRUSSIO ACID oxide of manganese, and is thus made to furnish (HCy; chemical equivalent 27), was first obchlorine gas, its hydrogen combining with the tained in its aqueous solution by Scheele in oxygen of the metallic oxide. Nitrate of silver 1782, who described it correctly as consisting detects its presence by a white curdy precipi- of hydrogen, carbon, and nitrogen; but the tate (chloride of silver), soluble in ammonia, true nature of the compound was determined but not in nitric acid, which forms on the ad- by Gay-Lussac 30 years later, who first obtained dition of a drop or two of its solution. The the anhydrous acid. This is a colorless, iningredients used for preparing hydrochloric flammable liquid, possessing a strong odor, acid, either upon a large or small scale, are which is recognized in peach blossoms; but common salt, sulphuric acid, and water. Dif- when exhaled from the pure acid it is so powerferent proportions are adopted, the most usual ful as to cause immediate headache and giddibeing equal weights of concentrated acid and ness, involving the most serious consequences of salt, or in the large way 6 parts of salt to 5 to life itself. The vapor is so remarkably volaof acid, being an equivalent of each. In the tile, that a drop of the acid congeals upon a small way, by distilling in a glass retort, may piece of glass by the rapid evaporation of a be used 3 parts or 1 equivalent of chloride of portion of the liquid. It boils at 80°, and sodium, 5 parts or 2 equivalents of oil of vit- freezes at 5° into a fibrous mass. At 64° its riol, and s parts of water. The acid mixed specific gravity is .6969. Its taste (a hazardwith 2 of water is poured when cool upon the ous test) is acrid and bitter like that of bitter salt contained in a large retort, and the remain- almonds. Its acid properties are feeble; the ing 3 parts of water are placed in the vessel faint red tinge it imparts to litmus paper soon serving as a condenser to receive the gas. Heat disappears; and it fails to decompose salts of is applied to the retort, and the acid gas distils carbonic acid. It exists in parts of many plants, over; the water in the condenser allows none as the kernels of peaches, almonds, plums, &c., of it to escape, so long as it is kept cool and is and in the leaves of the peach, laurel, &c. It not saturated. The aqueous solution obtained is also generated in the processes contrived for is of specific gravity about 1.17, and contains extracting it from various vegetable matters, 34 per cent. of dry acid. The residuum is bi. The chief source of the acid, however, is the sulphate of soda. The acid is so cheaply pre- animal kingdom, the blood, hoofs, horns, and pared in large chemical works, that it is seldom tissues of the animal body being made to furmade in the laboratory. It is an incidental nish cyanogen to potassium on being ignited product in the manufacture of carbonate of with carbonate of potash, and the cyanide thus soda, and was formerly allowed to go to waste. obtained and other cyanides of the same deriThe commercial article is often contaminated vation are employed to furnish the cyanogen with iron, which gives it a yellow color, though for the acid. Its detection in the cyanide salt, this is sometimes owing to organic matter, as Prussian blue, gave it the name of Prussic acid. cork or wood. Sulphuric acid is almost always Many methods have been devised for preparing present in it, and sometimes free chlorine and the anhydrous acid. The cyanide of mercury nitrous acid. Sulphurous acid has also been has been decomposed together with hydrochlofound to the amount of 7 to nearly 11 per cent. ric acid, thus producing chloride of mercury and Sulphuric acid is detected by the white pre- hydrocyanio acid; and sulphuretted hydrogen cipitate of sulphate of baryta produced when and also diluted sulphuric acid have by suitable chloride of barium is added to a diluted portion processes been substituted for the hydrochloric of acid. Protochloride of tin decomposes sul- acid. But the aqueous solution or medicinal phurous acid, and causes after a time a brown . acid is commonly prepared direct by some one precipitate to appear. Arsenic and chloride of of the numerous processes of the pharmacolead may sometimes be detected by a current pæias. The following, adopted in the United

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