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very brilliant combustion, accompanied with a loud detonation, will be the consequence. See Charcoal.

Experiment 9. Fuse a small quantity of nitre in a crucible, and, when in complete fusion, throw pulverized coal into it by small quantities at a time. The carbonaceous matter will decompose the nitre, and the bituminous part will burn away without acting upon it. This experiment will exhibit a mode of analysing coal; for every 100 grains of nitre that are decomposed in this way, denote ten grains of carbon.

Experiment 10. If 75 parts of nitre, 16 of charcoal, and 9 or 10 of sulphur be mixed together in a wooden mortar, the powder duly moistened, and afterwards passed through seives and dried, gun powder will be formed.

Remark. The mixture of these ingredients is performed in mills, called gun powder mills. The powder paste is afterwards grained, and for nice purposes glazed.

The excessive power of gun powder is owing to the formation, and sudden expansion, of several gases, such as carbonic, hydrogen, carburetted hydrogen, sulphuretted hydrogen, and azote; these gases being formed by the decomposition of the powder, and the union of the different elements agreeably to the laws of affinity.

NITRITE OF POTASH.

Experiment 1. If nitrate of potash be exposed to heat, in order to obtain oxygen gas, and the process stopped in time, the residue is a salt called nitrite of potash.

Rationale. The disengagement of oxygen from nitrate of potash, converts the nitric into the nitrous acid, which being already combined with the alkali forms nitrite of potash, a salt which deliquesces when exposed to the air, and gives out nitrous fumes.

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OXYMURIATE OF POTASH.

Experiment 1. If potash in a dry state, be made to come in contact with oxymuriatic acid gas, so that saturation may take place, the oxymuriate of potash will be formed.

Rationale. The oxymuriatic acid quits its gaseous state, and unites with the potash.

HYPER-OXYMURIATE OF POTASH.

Experiment 1. If potash be dissolved in water and oxymuriatic acid gas passed through it, by means of Woulf's apparatus, hyper oxymuriate of potash will result.

Rationale. When potash is dissolved in water, and in this state comes in contact with oxymuriatic acid gas, the latter is decomposed, and converted into hyper oxymuriatic and common muriatic acid. The former, as well as the latter combine with the alkali, and constitute the hyper-oxymuriate, and muriate of potash. The hyper-oxymuriate crystallizes in flat rhomboidal prisms of a silvery whiteness. Its taste is cooling, austere, and disagreeable, somewhat analogous to that of nitre; it dissolves in 16 parts of cold and 2-12 of boiling water; it is not sensibly altered by exposure to the air. When heated nearly to redness, it gives out more than a third of its weight of oxygen gas. It detonates with sulphur or phosphorus.

Mr. Parke has given a collection of some experiments with this salt, which may be interesting to the student. We shall here insert them.

Experiment 2. By gently triturating 3 grains of hyper-oxymuriate of potash, and one of sulphur in a mortar with a metallic pestle, a series of detonations takes place resembling the cracks of a whip.

Experiment 3. Take about six grains of hyper-oxygenized muriate of potash, and three grains of flour sulphur; rub them together in a mortar, and a smart detona

ting noise will be produced. Continue to rub the mixture hard, and the reports will be frequently accompanied with vivid flashes of light. If the same mixture be wrapped in paper, laid on an anvil, and smartly struck with a hammer, the report will be as loud as what is usually produced by a pistol.

Experiment 4. Take ten grains of the salt, and one grain of phosphorus. Treat this mixture as in the last experiment, and very violent detonations will be produced. It is advisable never to exceed the quantity of phosphorus that is prescribed here, and in other similar experiments.

Experiment 5. Take a similar quantity of hyper-oxygenized muriate of potash with three or four grains of four sulphur, and mix the ingredients very well on paper. If a little of this mixture be taken up on the point of a knife, and dropped into a wine glass containing some sulphuric acid, a beautiful column of flame will be perceived, the moment the powder comes in contact with the acid.

Experiment 6. Put a little hyper-oxygenized muriate of potash and a piece of phosphorus into an alc-glass, pour some cold water upon them cautiously, so as not to displace the salt. Now take a small glass tube, and plunge it into some sulphuric acid: then place the thumb upon the upper orifice, and in this state withdraw the tube, which must be instantly immersed in the glass, so that, on removing the thumb, the acid may be immediately conveyed upon the ingredients. This experi ment is an example of a very singular phænomenon, combustion under water.

Experiment 7. Proceed in all respects as in the last experiment, and add a morsel of phosphuret of lime. Here, besides the former appearance, we shall have combustion also on the surface of the water.

Experiment 8. Prepare a mixture of equal parts of lump sugar and hyper-oxygenized muriate of potash; put a small quantity of this mixture upon a plate or a tile; then dip a piece of sewing thread into a phial of sulphuric acid, so as to convey the smallest quantity of the

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acid: with this touch the powder, and an immediate burst of flame will be the consequence.

Experiment 9. Mix, without much friction, ten grains of hyper-oxygenized muriate of potass with one grain of phosphorus, and drop the mixture into concentrated sulphuric acid. This is an instance of detonation and flame being produced, by the mixture of a powder with a cold liquid.

Experiment 10. If strong nitrous acid be poured upon a small quantity of a mixture of hyper-oxygenized muriate of potash and phosphorus, flashes of fire will be emitted at intervals for a considerable time.

Experiment 11. Add a few grains of hyper-oxygenized muriate of potass to a tea-spoonful or two of alcohol, drop one or two drops of sulphuric acid upon the mixture and the whole will burst into flame, forming a very beautiful appearance.

Experiment 12. A mixture of hyper-oxygenized muriate of potash and arsenic furnishes a detonating compound, which takes fire with the utmost rapidity. The salt and metal first separately powdered, may be mixed by the gentlest possible triture, or rather by stirring them together on paper with the point of a knife. If two long trains be laid on a table, the one of gunpowder and the other of this mixture, and they be in contact with each other at one end, so that they may be fired at once; the arsenical mixture burns with the rapidity of lightning, while the other burns with comparatively 'extreme slowness.

ARSENIATE OF POTASH.

Experiment 1. If arsenic acid be saturated with potash, a salt will be formed called arseniate of potash.

Remark. This salt does not crystallize. It deliquesces, and changes vegetable blues to green.

Experiment 2. If the arsenic acid exists in excess, the super arseniate of potash is formed.

Remark. This is a transparent white salt, which crystallizes in four sided prisms, terminated by four sided pyramids.

Experiment 3. If a mixture of nitrate of potash and arsenious acid be detonated in a crucible, the residue will be arseniate of potash.

Remark. The arsenious acid being converted into the arsenic acid by the oxygen of the nitric acid, by combining with potash, the base of the nitre forms arseniate of potash.

ARSENITE OF POTASH.

Experiment 1. If white arsenite, or arsenious acid, be boiled in a solution of potash, a compound will be formed called arsenite of potash. See Arsenic.

Remark. The alkaline arsenites were formerly called livers of arsenic.

MOLYBDATE OF POTASH.

Experiment 1. If molybdic acid be saturated with potash, molybdate of potash will result. Or,

Experiment 2. If one part of molybdenum be detonated with four of nitrate of potash, a residue will be left, which contains the molybdate of potash.

Rationale. The oxygen of the nitric acid acidifies the metal, and the molybdic acid, thus formed, unites with the potash of the nitre.

TUNGSTATE OF POTASH.

Experiment 1. If tungstic acid be united with potash, tungstate of potash will be produced. See Tung

sten.

CHROMATE OF POTASH.

Experiment 1. Chromic acid combined with potash, forms chromate of potash. See Chromium..

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