a a. The large beaker glass. b. The small one, containing the chloride of lime. c. The tube and funnel down which the dilute sulphuric acid is poured. d d. Sheet of paper over top of large glass, with hole in centre to admit the tube. e. The little beaker used as a bucket.
Fourth Experiment.
Into a little platinum spoon place a small pellet of the metal sodium, and after heating it in the flame of a spirit lamp, introduce the metal into a bottle of chlorine, when a most intense and brilliant combustion occurs, throwing out a vivid yellow light, and the heat is frequently so great that the bottle is cracked. After the combustion, and when the bottle is cool, it is usually lined with a white powder, which will be found to taste exactly the same as salt, and, in fact, is that substance, produced by the combination of chlorine, a virulent poison, with the metal sodium, which takes fire on contact with a small quantity of water; and hence the use of salt for the preparation of chlorine gas when it is required on the large scale.
| Parts. | |
| Common salt | 4 |
| Black oxide of manganese | 1 |
| Sulphuric acid | 2 |
| Water | 2 |
Fifth Experiment.
Some Dutch metal, or powdered antimony, or a bit of phosphorus, immediately takes fire when introduced into a bottle containing chlorine gas, forming a series of compounds termed chlorides, and demonstrating by the evolution of heat and light, the energetic character of chlorine, and that oxygen is not the only supporter of combustion; chlorine gas has even, in some cases, greater chemical power, because some time elapses before phosphorus will ignite in oxygen gas, whilst it takes fire directly when placed in a bottle of chlorine.
Sixth Experiment.
The weight and bleaching power of chlorine are well shown by placing a solution of indigo in a tall cylindrical glass, leaving a space at the top of about five inches in depth. By inverting a bottle of chlorine over the mouth of the cylindrical glass, it pours out like water, being about two and a half times heavier than atmospheric air, and then, after placing a ground glass plate over the top of the glass, the chlorine is recognised by its colour, whilst the bleaching power is demonstrated immediately the gas is shaken with the indigo solution.
Seventh Experiment.
As a good contrast to the last experiment, another cylindrical jar of the same size may be provided, containing a solution of iodide of potassium with some starch, obtained by boiling a teaspoonful of arrowroot with some water; any chlorine left in the bottle (sixth experiment) may be inverted into the top of this glass and shaken, when it turns a beautiful purple blue in consequence of the liberation of iodine by the chlorine, whose greater affinity for the base produces this result. The colour is caused by the union of the iodine and the starch, which form together a beautiful purple compound, and thus the apparent anomaly of destroying and producing colour with the same agent is explained.