Remark. It may be proper to notice, that the mineral waters sold in our city are either simple water saturated with carbonic acid, and occasionally mixed with saline substances, or potash or soda in solution, supersaturated with that acid. The quantity of the ingredients is variable. It is a salutary beverage, and answers as a substitute in warm weather for spiritu ous liquors.

Experiment 4. If the carbonate of potash formed as in Experiment 1, be exposed to a strong red heat, it will be converted into the sub carbonate.

Remark. This salt contains exactly one half of the acid contained in the carbonate. It is more soluble in water; its taste is acrid; it deliquesces in the air, and is decidedly different in many other properties from the carbonate. The potash of commerce, the ka preparatum the alkali vegetabile mite, the sal absynthii, and the sal tartari are sub carbonates of potash. The salt of tartar is prepared, according to the Edinburgh college, in the following manner:

reduce

Experiment 5. Take super tartrate of potash or cream of tartar, and burn it live coals; among the mass to powder, and expose it in an open crucible to the action of a moderate fire, till it becomes white; dissolve it in warm water; strain the liquor, and evapo rate it to dryness, stirring it towards the end of the precess, and a white substance will remain.

Rationale. By the action of heat the acid of the tar tar is decomposed; water, carburetted hydrogen gas, and carbonic acid are disengaged, leaving the potash combined with carbon, and afterwards (when the carbon is burnt) with carbonic acid.

SULPHATE OF POTASH.

Experiment 1. If diluted sulphuric acid be saturated with potash, and the solution evaporated, crystals of sulphate of potash will be formed.

Experiment 2. If the residue which remains after the distillation of nitric acid from nitre by sulphuric acid, be dissolved in water, and if necessary the super

1

fluous acid saturated with potash, and the solution evaporated, sulphate of potash will likewise be formed.

Remark. The greatest part of the sulphate of potash of commerce is obtained from the residuum of the distillation of sulphate of iron with nitrate of potash, by lixivating it, supersaturating the solution with carbo nate of potash, filtering it boiling hot, and allowing it to crystallize. The crystals of sulphate of potash are six sided prisms, which are generally aggregated in

crusts.

It contains 100 acid, 130 base, and 20 water. This salt has been long known under the name of arcanum duplicatum, sal de duobus, vitriolated tartar, and vitriol of potash.

Experiment 3. If sulphate of potash be dissolved in sulphuric acid, and the solution evaporated, small slender six sided prisms will be formed, of supersulphate of potash.

Remark. This salt is acid; readily fusible, and when exposed to heat changes into sulphate of potash.

Experiment 4. If sulphate of potash be dissolved in water and muriate of barytes added, a white insoluble precipitate will be formed.

Remark. Hence sulphuric acid in sulphate of potash may be known by this re-agent; the precipitate is sulphate of barytes, and muriate of potash remains in so=lution:

Experiment 5. If sulphate of potash in solution be mixed with alcohol, a precipitate will take place.

Remark. Hence the sulphate is insoluble in alcohol; for the alkali unites with the water, and precipitates the salt.

Experiment 6. If a mixture of charcoal powder and sulphate of potash, be heated in a crucible, sulphuret of potash will result.

Remark. As charcoal decomposes sulphuric acid, in this instance it decomposes the sulphate; carbonic acid is disengaged and the sulphur remains united with the alkali in the state of sulphuret of potash or hepar sulphuris,

Experiment 7. If a mixture of equal parts of nitrate of potash and sulphur, be deflagated in a crucible, a compound will be formed called sulphate of potash with sulphur or sat polychrestum.

Rationale. The nitric acid of the nitrate of potash is decomposed by the sulphur, which is in part acidified by combining with its oxygen. The whole of the sulphur not being acidified, although united with the potash, forms the sulphate combined with sulphur.

SULPHITE OF POTASH.

Experiment 1. If sulphurous acid gas be passed through a solution of potash, sulphite of potash will result, which when evaporated will yield crystals in rhomboidal plates.

Experiment 2. If nitric acid be added to this salt, it will be converted into sulphate of potash.

Rationale. The sulphurous acid in the first unites directly with the alkali, and in the second experiment, the sulphurous is converted into the sulphuric by the oxygen of the nitric acid; nitric oxyd being evolved.

Experiment 3. If sulphite of potash be heated, sulphurous acid and water will be disengaged.

Remark. In this manner sulphurous acid was obtained by Scheele.

This salt contains 100 acid, 125 base, and 4.6

water.

NITRATE OF POTASH.

Experiment 1. If calcareous nitre, or nitrate of lime (which is the nitre of salt petre caves) be dissolved in water, the solution filtered, and potash added until no more precipitate is formed; the liquor then evaporated and crystallized, nitrate of potash will be formed.

Rationale. As nitric acid is combined with lime, the addition of potash precipitates the latter, and unites with the former into nitrate of potash.

Remark. In the Western United States, the manufacturers of salt petre use wood ashes, which they dispose either in tubs sometimes mixed with the salt petre earth, or lixivate into ley which they afterwards mix with the nitre earth. The nitric acid quits the lime, and unites with the potash. Immense quantities of this salt are made from the different caves. Nitre is produced spontaneously in various situations, sometimes efflorescing on the surface of the earth and on the walls of old buildings; it is also found in some vegetables, in mineral waters, dung-hills, &c. It may be artificially produced by the concurrent corruption, not strictly putrefaction, of animal and vegetable substances. Light earths, such as lime and marle, the refuse of soap fac tories, ashes, &c. being stratified for this purpose with straw, dung, and animal and vegetable substances; wetted with wine, blood, dung-hill water, and the mother water of salt-petre; and turned and exposed to the current of air.

In putrefaction the azote first unites with hydrogen and forms ammonia, after which the azote, in the next stage of corruption, unites with oxygen and forms nitric acid, which attaching itself to alkaline or earthy bodies, is afterwards converted into nitre by solution, filtration, evaporation, and crystallization. As nitre occurs in commerce it often contains a little muriate of potash and muriate of soda, from which it is easily purified by dissolving it in boiling water and filtering it: on cooling, the nitrate of potash crystallizes, and the other salts remain dissolved. This salt, when purified, is characterized by the following properties: It has a sharp bitterish, cooling taste. It shoots in pretty large crystals, which are generally six sided prisms, terminated by six sided pyramids; very brittle and permanent in the atmosphere; soluble in seven times their weight of water at 60°, and in an equal weight at 2129; melting when exposed to a strong heat, giving out at first oxygen, and afterwards nitrogen gas, until the whole acid be decomposed, and the potash alone remain behind. It deflagrates more or

less violently with all oxygenizable substances, oxydizing or acidifying them. When dried in the temperature of 70°, it consists acccording to Kirwan of 44 nitric acid, 51.8 potash and 4.2 water. It is decomposed by the sulphuric acid and baryta, and the sulphates of soda, ammonia, magnesia, and alumina.

Experiment 2. If nitre be fused in a crucible and cast into moulds, it forms crystal mineral or sal prunel.

Remark. The only change which nitre undergoes in this process, is the separation of the water of crystallization.

Experiment 3. If 2 parts of nitre be introduced into a retort with one of sulphuric acid, and distilled, nitric acid will be obtained. See Nitric Acid.

Experiment 4. If three parts of nitre, two of potash, and one of sulphur be mixed together, fulminating powder will be prepared. See Sulphur.

Experiment 5. If one part of nitre and two of cream of tartar (or common flour) be detonated, the residue will form black flux.

Rationale. The vegetable acid, if tartar be employed, or the vegetable substance, if flour be used, is decomposed as well as the nitrate of potash; tarbonic acid and water are disengaged, and the superfluous carbon remains mixed with the potash, forming the black flux for the fusion and reduction of metals.

Experiment 6. White flux is produced by detonating equal parts of nitrate of potash and acidulous tartrate of potash, or flour, în a similar manner.

Rationale. In this case, the oxygen of the nitric acid is sufficient to carry off all the carbon in the state of carbonic acid.

Experiment 7. Mix eight grains of nitrate of potash with four grains of phosphorus; place the mixture on a warm anvil, and strike it smartly with a hot hammer. This will produce a violent detonation. See Phosphorus.

Experiment 8. If ten grains of nitrate of potash be mixed well with three grains of pulverized charcoal, and the mixture thrown on a red hot fire shovel, a