954 SULPHUR 



pyrites, and affords, after being roasted and weather-worn, a considerable quantity of 

 copperas, which must be carefully separated by crystallisation from the alum. 



This liquor used formerly to be concentrated directly in leaden vessels ; but the 

 first stage of the operation, is now carried on in stone canals of considerable length, 

 vaulted over with bricks, into which the liquor is admitted, and subjected at the 

 surface to the action of flame and heated air, from a furnace of the reverberatory 

 kind, constructed at one end, and discharging its smoke by a high chimney raised at the 

 other. (See SODA MANUFACTURE.) Into this oblong trough, resting on dense clay, 

 and rendered tight in the joints by water-cement, old iron is mixed with the liquor, 

 to neutralise the excess of acid generated from the pyrites, as also to correct the 

 tendency to superoxidation in copperas, which would injure the fine green colour 

 of the crystals. After due concentration and saturation in this surface-evaporator, 

 the solution is run off into leaden boilers, where it is brought to the proper density 

 ior affording regular crystals, which it does by slow cooling, in stone cisterns. 



Copperas forms sea-green, transparent, rhomboi'dal prisms, which are without smell, 

 but have an astringent, acerb, inky taste ; they speedily become yellowish-brown in 

 the air, by peroxidation of the iron, and effloresce in a warm atmosphere ; they 

 dissolve in 1'43 parts of water at 60, in 0'27 at 190, and in their own water of 

 crystallisation at a higher heat. This salt is extensively used in dyeing black, 

 especially hats ; in making ink, and Prussian-blue, for reducing indigo in the blue vat, 

 in the China blue-dye, for making the German oil of vitriol, and in many chemical 

 and medicinal preparations. 



SULPHATE or LIME. See ALABASTER ; GYPSUM ; SELENITE. 



SULPHATE OF MAGNESIA. See EPSOM SALTS ; MAGNESIA, SULPHATE OF. 



SULPHATE OF IV2ANGANESE is prepared on the great scale for the calico- 

 printers, by exposing the peroxide of the metal and pit-coal ground together, and 

 made into a paste with sulphuric acid, to a heat of 400 Fahr. On lixiviating the calcined 

 mass, a solution of the salt is obtained, which is to be evaporated and crystallised. 

 It forms pale amethyst-coloured prisms, which have an astringent bitter taste, dissolve 

 in 2- parts of water, and consist of protoxide of manganese, 31'93 ; sulphuric acid, 

 35'87 ; and water, 32-20, in 100 parts. 



SULPHATE OF MERCURY. See MERCURY. 



SULPHATE OF POTASH. See FoTASH. 



SULPHATE OF SODA is commonly called Glauber's salt, from the name of the 

 chemist who first prepared it. See SODA, SULPHATE OF. 



SULPHATE OF ZINC, called also White Vitriol, is commonly prepared in the 

 Hartz, by washing the calcined and effloresced sulphide of zinc or blende, on the 

 same principle as green and blue vitriol are obtained from the sulphides of iron and 

 copper. Pure sulphate of zinc made be made most readily by dissolving zinc in 

 dilute sulphuric acid, evaporating and crystallising the solution. It forms prismatic 

 crystals, which have an astringent, disagreeable, metallic taste ; they effloresce in a 

 dry air, dissolve in 2'3 parts of water at 60, and consist of oxide of zinc, 28'29 ; 

 acid 28'18 ; water, 43'53. Sulphate of zinc is used for preparing drying oils for 

 varnishes, and in the reserve or resist pastes of the calico-printer. See ZINC. 



SULPHATES are saline compounds of sulphuric acid with oxidised bases. The 

 minutest quantity of them present in any solution may be detected by the precipitate, 

 insoluble in nitric or muriatic acid, which they afford with nitrate or chloride of 

 barium. They are mostly insoluble in alcohol. 



SULPHIDE OF CARBON. See CARBON, BISULPHIDE OF. 



SULPHITES are a class of salts, consisting of sulphurous acid, combined in 

 equivalent proportions with the oxidised bases. 



SULPHUR, Brimstone (Soufrc, Fr. ; Schwefel, Ger.), is an elementary substance 

 of great importance. It is abundantly distributed in nature, either in the free state or 

 in combination with other elements. In the free state it is found in three different 

 forms : 1st, as kidney-shaped lumps, disseminated through beds of tertiary and 

 recent formations ; 2nd, in calcareous formations of Miocene age, associated with 

 gypsum and rock-salt : it is under these circumstances that it Is principally found 

 in the mines of Sicily, which supply nearly all the sulphur of commerce in Europe ; 

 3rd, as sublimations around the mouths of volcanoes, where it is mixed with the 

 scoriae and lava. The solfataras of Guadaloupo and Pouzzales supply it in this state. 

 The sulphur mines of Sicily, of which the principal are situated near Cattolica, 

 Girgenti, Licata, Caltanisetta, Caltascibetta, Centorbi, audSommatino, supply immense 

 quantities of sulphur. According to Signor Mottura, the present annual production of 

 Sicily is about 160,000 tons. The Romagna, Spain, and Iceland likewise supply sulphur. 

 Sulphur is also found largely in nature in combination, as sulphuric acid, and with 

 metals forming sulphides ; these latter combinations are known as pyrites. Soo PYIUTKS. 

 Tho process for the separation of tho sulphur at the celebrated solfatara of 



