oxide of copper, and over dry quick-lime. Both processes gave results which conspire to show that it is constituted of

Messrs. Phillips and Faraday have not given any name to this compound. It may be called, provisionally, the subchloride of carbon.

Thus we have three distinct compounds of chlorine and carbon, viz.

At. of Chlor. At. of Carb.

It is probable that another chloride of carbon will hereafter be found, consisting of two atoms of chlorine and one of carbon.

SECTION IV.

Boron.

BORON was first obtained by Sir H. Davy in 1808 by the action of Voltaic electricity on boracic acid. When that acid, slightly moistened with water, was exposed between two surfaces of platina to a battery of 500 pairs of plates, an olive brown matter began immediately to appear on the negative surface, and gradually increased in quantity. This substance was found not to be acted on by water, but to dissolve with effervescence in warm nitric acid. When heated to redness on platina, it burned slowly, and boracic acid was regenerated. Hence the name of boron has been applied to it.

The same substance was afterwards obtained more abundantly by Gay Lussac and Thenard, by the action of potassium. Equal parts of potassium and very pure and vitreous boracic acid were put into a copper tube, which was gradually heated to

redness. At the temperature of 302° Fahr. the mixture became suddenly red, and the metal disappeared by acting on the boracic acid. By washing the residuum with warm water, a greenish brown or olive substance was obtained, which is the base or radical of boracic acid.

This substance is insoluble in water, it is destitute of taste, and does not affect vegetable blue colours. Mixed with chlorate or nitrate of potash, and projected into a red hot crucible, it burns vividly, and boracic acid is reproduced. In close vessels it may be exposed to a strong heat, without undergoing any change except an increase of density, for it now sinks in sulphuric acid of sp. gr. 1.844. It is a non-conductor of electricity.

When heated to 600° Fahr. in the open air, it burns vividly, absorbs oxygen, and affords boracic acid; but the coating, which it acquires of that acid, soon stops the combustion. The quantity of oxygen absorbed by a given weight has been investigated by Gay Lussac and Thenard, and by Sir H. Davy. According to the latter, 100 parts of boron absorb 174 of oxygen. Berzelius investigated the same problem indirectly, and was led to conclude that 100 of boron unite with 300 of oxygen to form boracic acid. Dr. Thomson,* after pursuing the same enquiry by different means, infers that 100 grains of boron condense 266.6 grains of oxygen, which are in the proportions of 6 to 16, indicating that the composition of boracic acid agrees exactly with that of the carbonic, as to the relative proportions of base and oxygen. According to this view, the atom of boron weighs 6; and each atom, to form boracic acid, combines with two atoms of oxygen, (8 x 2 = 16) and the atom of acid weighs 22. These results, however, are still liable to considerable uncertainty.

Boron with Oxygen.-Boracic acid.

I. This acid is very rarely to be found native; having been discovered hitherto only in the Lipari islands, and in the hot springs of Sasso in the Florentine territory. For pur

* Ann. of Phil. N.S. ii, 131.

poses of experiment, it is obtained from the purified borax of commerce, by one of the following processes:

1. To a solution of borax, in boiling water, add half its weight of sulphuric acid, previously diluted with an equal quantity of water. Evaporate the solution a little; and, on cooling, shining scaly crystals will appear, which consist of boracic acid. Let them be well washed with distilled water, and dried on filtering paper.

2. Let any quantity of borax be put into a retort, with half its weight of sulphuric acid, and half its weight of water. Boracic acid may be obtained by distillation, and may be purified, by washing in water, &c., as before. By neither of these processes, however, is it obtained perfectly pure; for electrical analysis discovers in it a minute portion both of alkali and of sulphuric acid. (Davy.)

II. Boracic acid has the following qualities:

1. It has the form of thin white scales, is destitute of smell; and nearly so of taste. Its specific gravity is 1.479.

2. It fuses, when heated, and loses its water of crystallization, which, according to Dr. Thomson, amounts to 44.5 from 100 of the crystals. If the heat be increased suddenly, before it has lost its water of crystallization, it sublimes; but, otherwise, it melts into a glass, which is permanent in the strongest fire, and has the specific gravity 1.803.

3. It is generally described as soluble in twelve parts of cold water, and in three or four of boiling water; but, according to Sir H. Davy, even boiling water does not take up above of its weight.

4. This solution reddens vegetable blue colours, and effervesces with alkaline carbonates. It is remarkable, however, that it reddens turmeric in the same manner as alkalis. (Faraday.)

5. It is soluble in alcohol, and the solution burns with a beautiful green flame.

Boron with chlorine.-Boron burns with considerable splendor in chlorine gas, but the compound which it forms has not been investigated. The same may be said of its combination with iodine.

Fluoboric Acid.

With the view of obtaining fluoric acid gas perfectly free from water, Sir H. Davy and Gay Lussac appear to have had recourse to the same expedient, viz. that of distilling perfectly dry boracic acid with fluate of lime. When these substances were exposed to a strong heat in an iron tube, in the proportion of one part of the former to two of powdered fluor spar, a gas was collected in great quantity, which exhibited singular properties, and to which Messrs. Gay Lussac and Thenard have given the name of gas fluoborique or fluoboric acid gas. It may, also, be obtained by distilling in a retort one part of vitreous boracic acid with two of fluor spar and 12 of sulphuric acid. One hundred cubic inches weigh 73.5 grains.

This gas, according to the latter chemists, appears to contain no water, and to have so strong an affinity for it, as to take it from other gases which hold water in combination. Hence, when mixed with most of those gases, on which it does not exert a chemical action, such as atmospheric air, it loses its transparency and becomes cloudy.

With ammoniacal gas it unites in two proportions. If the alkaline gas be put first into the tube, equal measures combine together, and the compound is neutral. But if we admit fluoboric gas by bubbles to the alkaline gas, we obtain a compound, with an excess of base, consisting of one measure of fluoboric gas to two of ammonia.

Fluoboric gas is absorbed copiously by water, which takes up 700 times its bulk, and acquires the specific gravity 1.77. The saturated solution has the causticity and aspect of strong sulphuric acid; requires for ebullition a temperature considerably exceeding 212° Fahrenheit; and is condensed again in stria which contain much gas. From analogy, Gay Lussac supposes that nitric and even sulphuric acids would, if they could be obtained free from water, be equally elastic with this acid.

When potassium or sodium was heated in fluoboric gas, Gay Lussac and Thenard obtained fluate of potash or soda, and the base of the boracic acid was separated.

The liquid acid acts almost as intensely as sulphuric acid on vegetable substances. It blackens paper, and affords a true ether with alcohol. It has no effect in corroding glass.

From analysis, Gay Lussac and Thenard, as well as Sir H. Davy, have determined it to be a compound of boracic and fluoric acids, in proportions not yet ascertained.

SECTION V.

Phosphorus.

PHOSPHORUS was discovered about the year 1669 by Brandt, an alchemist of Hamburgh, while employed in the research after the art of converting the baser metals into gold and silver; and afterwards by Kunckel, a German chemist. But the method of preparing it was not publicly divulged by either of those persons; and it was not till 1737, that a commission, appointed by the French Academy of Sciences, was instructed by a stranger in the process. It consisted in evaporating putrid urine to dryness, and distilling the residuum at an intense heat in a stoneware retort. Margraff improved the process by adding a salt of lead to the urine; and in 1769 Gahn, of Sweden, having discovered the phosphoric acid in bones, invented the method of preparing phosphorus which is now generally followed.

I. Phosphorus is an inflammable substance, and is distinguished by the following external characters.

(a) It has generally a flesh-red colour, but, when carefully purified, may be obtained colourless, and perfectly transparent. Its specific gravity is 1.77. It is necessary to preserve it under water in well-ciosed bottles.

(b) It is so soft that it readily yields to the knife.

(c) It melts at about 109° or 110° Fahrenheit, and boils at 550°. When melted, it must be covered with water, in order to prevent it from inflaming. Exposed to a heat of between 140° and 160° Fahrenheit, and suddenly cooled, it becomes black; but, if slowly congealed, it remains transparent and colourless: when cooled at a moderate rate, it assumes the