370 



CHEMISTRY. 



jnioM- 



The arrangement is represented in the following en- 

 graving, m si. 



In the annexed 

 figure, a represents 

 the vessel in which 

 the gas is manu- 

 factured ; 6 is a 

 funnel, by means 

 of which more acid 

 can be continually 

 added to the sul- 

 phide ; c is the 

 pipe through which 

 the gas passes to 

 the vessel d, in 

 which water is 

 placed, which ab- 

 sorbs and forms a 

 watery solution of 

 the gas ; e is a 

 bent tube, which 

 allows of the 

 escape of uncon- 

 densible gas. We 

 need scarcely remark, that the cork in each vessel 

 should be air-tight in their necks, so as to prevent the 

 escape of gas into the air. Instead of water, a solution 

 of ammonia may be used in the vessel d, by which the 

 hydrosulphate of ammonia is formed a usufuland neces- 

 sary test in the laboratory. Sulphuretted hydrogen gas 

 is a deadly poison, and is partly the cause of many 

 Hisnsisra common in badly-drained districts. It may be 

 detected by means of lead in the form of a solution of 

 the acetate. It is readily decomposed by chlorine ; hence 

 the use of chloride of lime in places wherever it abounds. 

 The following experiments will impress these facts on 

 the minds of our readers. 



Experiment 61. To detect Sulphuretted Hydrogen. 

 Dissolve a little sugar of lead in water; into this dip 

 some white blotting-paper. On holding a strip of this 

 paper in the jar of gas, or over a foul drain, it will tuni 

 black at once. 



Experiment 62. Into a jar of the gas introduce a 

 Jttle chlorine. The sulphur will be immediately sepa- 

 rated, and all smell will vanish. 



Experiment 63. Magic Writing. On a piece of 

 paper write anything, using as ink a little solution of 

 sugar of lead, and a quill pen. Let it dry, and the 

 writing will be invisible. On moistening it with water, 

 and holding it in a jar of sulphuretted hydrogen gas, or 

 over a drain, the writing will at once be evident, and in 

 black characters. 



Sulphur unites with many substances, forming what 

 are termed sulphides. Of these are the sulphide of 

 antimony, iron and copper pyrites, the sulphide of lead, 

 commonly called galena, &c. The combination of iron 

 and sulphur is readily .produced by holding a roll of 

 brimstone against a red-hot iron rod, when the latter 

 will fall down in globules of the sulphide of the metal. 

 Many metallic ores, besides those we have named, con- 

 tain the metal united with sulphur. The combination 

 of sulphur and carbon, known as the bisulphide of 

 carbon, will be further noticed as a solvent of phosphorus, 

 when we describe that element. 



SELENIUM, 



WE shall here call attention to an element which is 

 rarely met with. It chiefly resembles sulphur in its 

 relations : symbol, 8e ; equivalent. :'.'.!.">. With oxygen 

 it forms selenio acid ; anil, combined with hydrogen, it 

 affords seleninretted hydrogen gas. It may be reckoned 

 only as a chemical curiosity, for as yet it has had no 

 application of any value whatever ; and, indeed, its 

 scarcity renders such, for the present, impossible. 



PHOSPHORUS. 

 Bvt a fsw years ago phosphorus was merely a chemical 



curiosity, or an object for the amusement of young per- 

 sons, by its peculiar properties. It has, however, lately 

 become an important article of commerce ; and in tho 

 manufacture of lucifer-matchos thousands of persons 

 liii'l employment. 



Phosphorus is obtained chiefly from bones, which con- 

 tain a large amount of phosphate of lime.* The bones 

 are first calcined, and sulphuric acid added thereto. This 

 decomposes the phosphate of lime. The liquid is evapo- 

 rated to the consistence of a syrup, and mixed with 

 charcoal The mixture is then strongly heatod in a 

 retort, by which the phosphoric acid is decomposed, and 

 the phosphorus distilled over as a wax-like substance. 

 It is received in vessels containing cold water. Its 

 symbol is P, and the equivalent 32. 



At ordinary temperatures phosphorus undergoes a 

 slow combustion if exposed to the air ; and hence it 

 should always be kept in bottles containing water, so 

 that no part of the substance be above the surface of 

 the liquid. We would impress this precaution strongly 

 on our readers, as we have witnessed some serious 

 results arising from its neglect : in one instance, an 

 extensive laboratory was nearly destroyed by fire, 

 through a stick of phosphorus having been left care- 

 lessly on a wooden table. It should never be cut except 

 under water, nor touched by the finger, as the burn it 

 produces is very serious, and difficult to cure. It takes fire 

 at a temperature of about 150. It has, however, the power 

 of assuming what is termed an allotropic condition ; for 

 after .having been heated till it obtain a red appearance, 

 it loses its power of spontaneous inflammability, and 

 becomes entirely changed in many of its properties. In 

 this respect it much resembles sulphur, which has also 

 the power of becoming allotropic. It combines with 

 oxygen, hydrogen, &c. , in a manner of which we shall 

 presently speak. The following experiments will illus- 

 trate some of its ordinary properties. 



Experiment 64. Rub a small piece, by means of a 

 pair of iron nippers, against a wall in a dark room ; 

 every mark will appear of a beautiful white light. This 

 effect is called phosphorescence. 



Experiment t>5. Boil a few small pieces of phos- 

 phorus in a flask, with some water ; sparks will rise in 

 all directions through the liquid : and if, at the conclusion 

 of the experiment, you throw out the water into the open 

 air on the ground, a splendid flash of light will be shown. 



Ejj>eriment 66. Into a test-tube pour half an ounce 

 of olive oil, and add one small piece of phosphorus ; 

 heat gently over the spirit-lamp. A small quantity of 

 the phosphorus will dissolve ; and by rubbing the oil over 

 the hands and face they will become quite luminous. 

 This is a harmless experiment, and the oil can bo easily 

 removed by soap and water. 



It is owing to the presence of phosphorus that, many 

 animal bodies afford a lambent light at ordinary tem- 

 peratures. This is often noticed at sea, and during 

 summer evenings : the wake of a steam-vessel, and tho 

 back-water cast from the paddle* or screw, frequently 

 present a most beautiful appearance, owing to tint 

 millions of small insects emitting a phosphorescent light. 

 Crabs, lobsters, and other animal substances, the glow- 

 worm, and fire-fly, owe their luminosity to the same 

 cause. Oyster and other shells often afford a phospho- 

 rescent light after having been heated. 



A very curious application of phosphorus may be 

 made by its solution in the bisulphide of carbon, to 

 which a little wax may be added. If the liquid so pro- 

 i be poured upon paper, cloth, etc., after a short time 

 such will burst into flame. Captain Norton has prop 

 to employ the liquid for the purposes of warfare. Ue 

 'u it in shells, which may be fired in the usual 

 manner. On such coming in contact with the sails or 

 hull of a ship, they will at once break, and, spreading the 

 liquid on all sides, cause the destruction of the vessel. 

 We cannot too strongly caution our readers as to the use 

 of this liquid, as whatever combustible substance it 

 touches it at once inflames. Even pouring water over it 

 will not ensure subsequent safety. 



8c ante, p. SSO, tt ley. 



