SULPHUR. 



SULPHUK. 



due to a fourth modification of sulphur, which is black ; it is formed 

 on many times repeating the process of heating a quantity of sulphur 

 to 600 Fahr., and suddenly cooling in cold water. 



Sulphur is insoluble in water, but dissolves in alcohol, if both sub- 

 stances are exposed to each other in the state of vapour : on the 

 addition of water, the sulphur is precipitated. It is dissolved by boil- 

 ing oil of turpentine ; the solution has a reddish-brown colour, and, 

 on cooling, minute crystals of sulphur are deposited. It is readily 

 taken up by chloride of sulphur, and is soluble in about three times its 

 weight of bisulphide of carbon ; the elastic variety is, however, not so 

 soluble. Sulphur is also soluble to a small extent in ether and in 

 chloroform. 



Sulphur is a bad conductor of heat ; it is very volatile, and when it 

 is rubbed in the dark on a brick, or any other substance by which it is 

 heated, though not sufficiently to inflame it, an extremely weak blue 

 flame arises, exhaling a peculiar odour; tins flame is not, however, 

 occasioned by combustion, it merely accompanies the evaporation of 

 the sulphur, for a cold body held over it is covered with flowers of 

 sulphur. When sulphur is heated, it begins to vaporise before it 

 fuses ; at 600 Fahr. it is rapidly volatilised, and in close vessels is 

 condensed without change. The specific gravity of the vapour of 

 sulphur is 6-617 at 900" Fahr., but at 1900 Fahr. it is 2'2. Its com- 

 bining volume below 1500 Fahr. is J, but at 1900 Fahr. it is 1. It 

 unites directly with some metals to form sulphides. 



When heated in the air sulphur quickly takes fire and burns with a 

 pale blue flame, generating much heat. 



The equivalent of sulphur is 16. 



Compounds of Sulphur and Usyjen are seven in number, namely : 



Sulphurous acid 

 Sulphuric iicid . 

 Hrpoftulphnrous acid 

 Hrpwulpharic acid . 

 Trithionic acid 

 Tctratbionic acid 

 IVnutliionic acid . 



SO, 



so, 



8,0, 

 80 S 

 6.0, 

 8.0, 

 S.O. 



Sulphur 

 per cent. 

 50-00 

 40-00 

 66-66 

 H-45 

 54-53 

 61-53 

 66-66 



Oxygen 

 per cent. 

 50-00 

 80-00 

 33-34 

 55-55 

 45-45 

 38-47 

 33-34 



,l<urmu of id (SO,) Sulphurous anhydride. This gas escapes, in 

 the gaseous state, from fissures in the ground in the neighbourhood of 

 volcanoes. It is artificially obtained in the pure state on heating 

 about two {tarts of mercury with three of strong sulphuric acid : 



II* + 4(UO, SO,) = HgO,, 280, + 4HO + 2SO, 



Mercury. Sulphuric 

 acid. 



Bisulphite of 

 mercury. 



Water. 



Sulphurous 

 acid. 



T clippings may be economically substituted for mercury, but 

 M met with in commerce they generally contain matters that affect 

 the purity of the gas. On the large scale, solution of sulphurous acid 

 is preferable to the gas itself, and is manufactured directly from 

 Hiiljilmr. The latter is burnt in a furnace, and the sulphurous acid 

 j.i .lu.;ed cooled by passing through earthenware tubes surrounded by 

 .iter. It is then made to ascend through a tall and wide wooden 

 column packed with pumice-stone that has been digested in hydro- 

 chloric acid and well washed. In ascending the sulphurous acid meets 

 with a stream of water, the flow of which is so regulated that a 

 saturated solution shall flow off at the bottom of the column. It is 

 stored for use in a closed reservoir. 



Sulphurous acid gas is colourless, and permanently elastic ; that is, 

 ndensed into a fluid or solid by exposure to common degrees of 

 c'lM umler the ordinary pressure. It condenses to the liquid state, 

 however, on being passed through a tube surrounded by a freezing 

 mixture of ice and salt In this condition it may be preserved in her- 

 metically sealed tubes, on the interior of which, at 60 Fahr., it exerts 

 a pressure of two and a half atmospheres. At 105 Fahr. it freezes 

 to a colourless, transparent, crystalline solid. 



Sulphurous acid gas has a pungent and suffocating odour, being that 

 experienced whenever sulphur is burned ; its taste is disagreeable and 

 aciil ; it extinguishes burning bodies, is not inflammable, and is fatal 

 to animals. Water at 60 Fahr. dissolves from 33 to 37 times its 

 volume of this gas ; by heating the solution it is evolved unaltered. 

 The solution possesses the smell of the gas itself ; and, like it, lias the 

 property of bleaching some vegetable and animal substances : hence 

 the employment of the vapour of burning sulphur in whitening hops, 

 silk, wool, and straw. 



hundred cubic inches of sulphurous acid gas weigh 68'8 grains ; 

 its density therefore is about 2'22. Being so much heavier than an- 

 il may be collected in vessels by displacement. [OASES, COLLECTION OF.] 



The aqueous solution of sulphurous acid, when exposed to oxygen, 

 slowly combines with it, and the result is sulphuric acid ; but 

 unless moisture be present, no combination takes place between these 

 two gases. 



Sulphurous acid combines with various bases to form salts, which 

 are called tulphita. When, for example, this gas is passed into an 

 aqueous solution of ammonia, they readily combine, and the resulting 

 salt is sulphite of ammonia, which may be obtained in prismatic 

 crystal*, ft is very soluble in water, and produces much cold during 



solution ; by exposure to the air it attracts oxygen, and becomes 

 sulphate of ammonia. When, however, dry sulphurous acid gas and 

 dry ammoniacal gas are brought into contact, deep yellow-coloured 

 crystals are formed, which have been termed stUphitammon, or im- 

 properly suljamide; they contain the elements of sulphurous acid and 

 ammonia combined, but in a different mode to that which forms 

 anhydrous sulphite of ammonia. By exposure to the air sulfamide 

 becomes white, deliquesces, and gradually becomes sulphate and hypo- 

 sulphate of ammonia. 



The alkalies potash and soda, the alkaline earths, and several metallic 

 oxides, may be combined with sulphurous acid, and they form sulphites ; 

 but these compounds are not of much importance, except perhaps that 

 of soda. [SODIUM, sulphite of.] In contact with air they are slowly 

 converted into sulphates. 



Sulphuric Acid (HO, SO,). This acid has been long known, and is 

 very extensively employed, 100,000 tons being annually consumed in 

 Great Britain alone. When combined with water, in which state it is 

 best known, it was originally, and still is frequently, called oil of 

 ritriol : first, because it is an oily looking liquid ; and secondly, on 

 account of its being obtained from green vitriol, or copperas, now 

 called sulphate of iron. 



The process just alluded to was first followed at Nordhausen in 

 Germany, and the peculiar compound of sulphuric acid and water pro- 

 duced by it is still called Nordhausen oil of vitriol, to distinguish it 

 from common oil of vitriol, a different compound as regards the water 

 which they contain, and obtained by a different process. We shall 

 first describe the original process and product. 



Iron pyrites is a well known and very abundant natural substance : 

 it is correctly termed bisulphide of iron, and consists of two equivalents 

 of sulphur and one equivalent of iron. When certain varieties of this 

 compound are exposed to air and moisture, both the sulphur and iron 

 are oxidised at the expense of the oxygen of the air ; and though 

 sulphur by itself is incapable of undergoing this change, yet, when 

 combined with iron, it acquires from the air sufficient oxygen to 

 become sulphuric acid, and the iron attracts enough to become 

 protoxide ; and these combining together, and with water, constitute 

 the well-known crystalline body, hydrated sulphate of protoxide of 

 iron, usually called, for brevity's sake, merely sulphate of iron, and 

 originally green vitriol. This consists of one equivalent of sulphuric 

 acid, one of protoxide of iron, and seven equivalents of water. Sul- 

 phuric acid consists of three equivalents of oxygen and one equivalent 

 of sulphur. In order to procure the acid from it, the salt is mode- 

 rately heated, so as to expel the greater part of the water : in this 

 state it is put into earthen retorts, and subjected to a very high tempe- 

 rature, during which there comes over and condenses in the receiver a 

 dark -coloured dense fluid, which is the Nordhausen oil of vitriol ; the 

 cause of the colour has not been ascertained, but it appears to be an 

 accidental and not a necessary accompaniment. This liquid emits a 

 white vapour when exposed to the air, and hence it is called famiii;/ 

 sulphuric acid. It is composed of two equivalents of sulphuric acid 

 and one equivalent of water (HO, 2S0 3 ). 



Now it happens that anhydrous sulphuric acid is more volatile than 

 that combined with water, so that when the above acid is heated in a 

 retort, there first comes over and condenses in the receiver anhydrous 

 sulphuric acid, and there remains in the retort hydrated sulphuric 

 acid. 



We shall first and briefly state the properties of the anhydrous acid. 

 It is a colourless crystalline solid, is tough and elastic, liquefies at 66, 

 and boils at a temperature between 104" and 122, forming a trans- 

 parent vapour, provided no water is present ; it unites with moisture 

 when exposed to the air, and forms with it dense white fumes. It is 

 sometimes prepared as a matter of curiosity, but is hardly applied to 

 any use. Though called an acid, it in reality possesses no acid pro- 

 perties, and may be moulded in the fingers, like wax, without injuring 

 the skin. When thrown into water it hisses as red-hot iron would do, 

 anrl then has the usual powerful properties of common hydrated 

 sulphuric acid. 



The hydrated sulphuric acid, commonly called oil of vitriol, or simply 

 sulphuric acid, is the compound which is so largely employed in nume- 

 rous chemical operations and manufactures. It is, however, and has 

 indeed for many years been, prepared in a much preferable mode to 

 that described by the decomposition of sulphate of iron. The process 

 consists in oxidising sulphurous acid through the agency of nitrous 

 acid. 



First, nitrate of potash or soda is decomposed by the addition of 

 sulphuric acid, in the same mode as that employed for preparing nitric 

 acid. 



Sulphur is then burned in a furnace so contrived that the current 

 of air which supports the combustion conducts the gaseous products, 

 including the nitric acid fumes and excess of air, into large leaden 

 chambers, the bottoms of which are covered to the depth of a few 

 inches with water. The nitric acid of the nitre, composed of oxygen 

 and nitrogen, is here decomposed, yields oxygen to a portion of the 

 sulphurous acid formed by combustion, and converts it into sulphuric 

 acid. The nitric acid, on losing oxygen, is converted into nitric oxide, 

 which, by mixing with the air at the moment of its separation, com- 

 bines with its oxygen, and gives rise to red nitrous acid vapour. The 

 gaseous substances present in the leaden chambers are therefore 



