THE POPULAR EDUCATOR. 



many they are very polite to foreigners. 5. The roots of the forest 

 were his only nourishment. 6. Water, on this occasion, took the 

 place of wine. 7. A scholar has taken the place of teacher. 8. They 

 use pencils instead of pens. 9. Travelling gives me very much plea- 

 sure. 10. My children have learnt writing and reading of me. 11. 

 Let us go ; this long waiting is disagreeable to me. 12. They gene- 

 rally prefer sitting to standing. 13. He learnt to labour in his youth. 

 14. We learnt to write together. 15. I hate writing; on the contrary, 

 I like painting so much the more. 16. He understands drawing better 

 than painting. 17. We heard the bells pealing and the cannons thun- 

 dering. 18. The howling of the storm, and the wild raging of the 

 waves, heightened still further the courage of the brave captain and 

 his crew, instead of depressing it. 19. Thinking God more benevolent 

 than just, is equivalent to dishonouring him (Gellert). 20. This scho- 

 lar's inexcusable behaviour vexed the teacher. 



LESSON'S IN CHEMISTRY. XY. 



SULPHUR AND ITS COMPOUNDS. 



SULPHUR: SYMBOL, S ATOMIC WEIGHT, 32 DENSITY OP VAPOUR AT 

 1,000 CENT., 32. 



SULPHUR is a yellow solid which is found mixed with the soil 

 in many volcanic districts. It also appears in combination with 

 metals forming a large class of ores named sulphides ; and more- 

 over it takes some part in animal and vegetable economy, for it 

 is found in albumen, hair, garlic, etc. The localities from which 

 the greater part of the sulphur of commerce is procured are the 

 valleys of Noto and Mazzaro, in Sicily. Here it is mixed with 

 clays and breccia. Some sulphur is derived from metallic sul- 

 phides, particularly iron pyrites, FeS 2 , but this is liable to 

 contain arsenic. The pyrites is heated in conical clay tubes, 

 FeS remains behind, while the other atom of sulphur ia 

 liberated. The Sicilian sulphur undergoes partial purification 

 at the mines by being submitted to a rough sublimation that 

 is, when heated to 490 Cent, the sulphur begins to boil, and to 

 come off in vapour. This is passed into a chamber in which it 

 is cooled, the vapour condensing into a fine yellow powder 

 flowers of sulphur. Sometimes the melted sulphur is run into 

 wooden moulds, by which it is converted into cane sulphur, or 

 "brimstone. 



Properties. Sulphur is a brittle solid without taste or smell. 

 When rubbed it emits a peculiar odour, and becomes negatively 

 electrified. It is a very bad conductor of heat, and when a stick 

 of brimstone is held in the hand in contact with the ear it 

 crackles and frequently falls to pieces from the unequal expan- 

 sion. It is quite insoluble in water, as may be easily seen by 

 examining a piece of brimstone which has been for years in a 

 vessel of water from which a lady's lap-dog drinks. The edges 

 of the roll will be found as sharp as the day when it was first 

 put into the water. Alcohol and ether have but a slight solvent 

 action upon it, but the bisulphide of carbon, CS 2 , dissolves it 

 freely. Sulphur exists in three modifications. The sulphur 

 which appears in nature when crystallised, is in rhombic octa- 

 hedra. This same shape is assumed when the bisulphide of 

 carbon, which holds sulphur in solution, is evaporated. These 

 latter crystals, however, are transparent. To procure the second 

 modification, sulphur is melted, and when it is covered with a film 

 on cooling, a hole is broken through the crust, and the sulphur 

 which is still liquid is poured out ; the under surface of the film and 

 the sides of the crucible will be found covered with long needle- 

 shaped transparent crystals belonging to the oblique prismatic 

 form, and having a specific gravity of T98, whereas that of tli3 

 native sulphur is 2'07. These crystals soon become opaque, and 

 when touched crumble into powder, the particles of which are 

 found to be crystals similar to those of native sulphur. Thus 

 sulphur is " dimorphous," or capable of crystallising in two dif- 

 ferent systems. The third and more remarkable variety is pro- 

 duced by heat. At 115 sulphur begins to melt, forming a pale 

 yellow mobile liquid. Upon raising the temperature its colour 

 becomes darker, and at 250 it is an opaque mass, so viscid as 

 to be poured from the vessel with difficulty ; 20 higher it again 

 resumes its fluid condition, and if it be poured into cold water 

 when in this state, it becomes a soft and plastic mass of an 

 amber-brown colour, and so tenacious that it can be drawn out 

 into fine threads. It is in this condition that casts of medals, 

 etc., are taken for electrotyping. After a lapse of some time it 

 returns to its yellow colour and solid condition. In passing 

 from one of these conditions to another, there is invariably a 

 remarkable alteration, in temperature. 



Oxides of Sulphur. All the oxides of sulphur which are known 

 possess acid properties : 



Hydric Sulphite or Sulphurous Acid, H a SO s . 



Hydric Sulphate or Sulphuric Acid, H,,SO 4 . 



Hydric Hyposulphite or Hyposulphurous Acid, H a S a O s . 



Eydric Dithionate or Dithionic Acid, HsS.,0,,. 



Hydric Trithionate or Trithionic Acid, H a S 3 O . 



Hydric Tetrathionate or Tetrathionic Acid, H a SO 8 . 



Hydric Pentathionate or Pentathionic. Acid, H 3 S 5 O . 



_ Sulphurous Acid (symbol, SOX, ; combining weight, 64 ; den- 

 sity, 32). Sulphur burns in oxygen with a lilac-coloured flame, 

 and the sole product of the combustion is the gas, SO , 

 which has a density double that of oxygen, for the gas occu- 

 pies the same volume as the oxygen from which it is made, 

 thus : 



S + 3 = SO,. 

 +2 = 2. 



The gas may be procured more easily by cautiously heating 

 in a flask a mixture of 3 parts of sulphur and 4 of manganese 

 dioxide ; the reaction is thus expressed : 



MnO, + S, =MnS + SO 3 . 



A third process consists in heating sulphuric acid with copper 

 or mercury in an ordinary flask 



Hg + 2H,SO. = HgSO 4 + 2H a O + SO,. 



The gas is well known for its suffocating odour. It cannot 

 support combustion. Water at Cent, dissolves 68'8 volumes 

 of the gas, but this solution gradually absorbs oxygen from 

 the air, and becomes converted into sulphuric acid. By 

 causing the gas to traverse a tube surrounded by a mixture 

 of salt and ice, or by submitting it to a pressure of 2 atmo- 

 spheres, it liquefies into a colourless limpid fluid. 



Fig. 46 shows the arrangement. The gas, to purify it, ia 

 sent through a " wash bottle," w, which contains concentrated 

 sulphuric acid, by which the gas is dried. The liquefied sul- 

 phurous acid collects in the tube on the jar s, and is preserved 



Fig. 46. 



by hermetically sealing its neck. Of course, when exposed to 

 the air, the liquid evaporates rapidly, and by this means a tem- 

 perature of 60 Cent, may be obtained. This experiment may 

 be easily shown by wrapping the bulb of an alchohol thermo- 

 meter in muslin, and pouring some of the liquid upon it. 



Sulphurous acid possesses great bleaching powers, and also 

 antiseptic properties. If a red rose be held over the fumes of 

 ignited sulphur its colour will be immediately changed. Chlorine 

 cannot be used in bleaching silk, wool, and especially straw, as it 



