USES OF NITROGEN. To the Editor of the Chemist. SIR,-Observing in your little Publication, page 108, the subject of Nitrogen, I wish to make a few remarks, which may not prove uninteresting to your readers.

You say, we are as yet ignorant of the utility of this gas in constituting so large a portion of the atmosphere; the mode of its operation; and that it is the oxygen alone that disappears in respiration and combustion. It has been, you will allow, most satisfactorily proved, that oxygen only breathed, caused a laborious and hurried respiration, and is incapable long of supporting animal life; if so, why doubt for a moment whether or not oxygen (Query, azot?) be inhaled, and inform me how it is supplied, to be emitted in such large quantities in the decomposition of all animal substances. In my experiments I have proved, and therefore agree with Mr. Troussett, that the gas emitted from the skin is pure azot; and as, in vegetables, it combines with carbon, hydrogen, and a small portion of oxygen, to form oil, wax, resin, &c. so in my opinion does it combine with the same substances, though in different proportions, to form the fat, gelatine, and muscular fibræ of all living animals.

Tocavita, half a mile from the village, to the eastward, on Holy Saturday, in the year 1810, by Cecilia Corredor. We repaired to the spot, and saw the excavation which it was necessary to make to get out the mass, for it was almost buried, a single point of some inches only appearing above the surface. The hill of Tocavita, as well as the land about Santa Rosa, consists of a sand stone of the secondary formation, which is there of a considerable extent. Santa Rosa is about twenty leagues to the northeast of Bogota, in 5° 40' lat., and 75° 40' long. west of Paris, and 2744 metres above the level of the sea. The inhabitants of the village all united their efforts to fetch this mass of iron down; it remained eight years at the municipality, and was afterwards for seven years made use of by the farrier.

The iron, though full of holes, did not any where contain signs of being covered with a vitreous cake or varnish. It was malleable, granulated, easily filed, had a brilliant white colour, and its specific gravity was 7.3. This mass contained 102 cubic decimetres, and consequently must have weighed about 750 kilogrammes, upwards of 1640 pounds. At the same time that this mass was discovered, a great many fragments were also found at different other parts of the hill; and during our short stay in that neighbourhood, we collected several small pieces. We analysed a portion of the large mass in the following manner:-A piece, weighing 1gramme 28. of this mass having been thrown into nitric acid, was rapidly dissolved, leaving only a very small residuum; we then evaporated nearly to dryness; in order

to

oxidate the iron sufficiently, water was then added, and a precitate produced by ammonia. The oxide separated by the filter was washed in warm water; the ammoniacal liquid was tinged: green; and the prussiate of potash produced a precipitate of a light green, which indicated the presence of nickel and not of copper. When this ammoniacal solution

was reduced to the half of its volume by evaporation, we added caustic potash to it; and, to be certain of the entire decomposition of the double salts of ammonia and nickel, we evaporated to dryness. Water was added to the residuum, and the oxide of nickel which we obtained, washed, and calcined, weighed 0.14. By treating the oxide of iron obtained with acetic acid, a further proportion of 0.01 of nickel was obtained. Thus the elements of this substance are oxide of iron 1.17, oxide of nickel 0.15; or 100 parts contain 91.41 iron, 8.59 nickel. The authors then give an account of the analysis which they made of several other meteoric masses of iron, and they found in all of them about 8 parts in the 100 to be nickel. In some of the stones they found a small portion of insoluble matter, which they conjecture to be a mixture of iron, nickel, and perhaps chromium.

DICTIONARY OF CHEMISTRY. ANATASE. A very scarce mineral, found only in Dauphiny and Norway, remarkable for showing a variety of colours by reflected light. ANATTO. A pigment obtained from the seeds of the bixa orellana, a tree cultivated in America and the West Indies, used in dyeing and colouring cheese.

ANDALUSITE. A massive mineral, of a flesh colour, first found in Andalusia, in Spain, whence its

name.

ANDREOLITE, harmotome. Cross

stone.

ANHYDRITE. A species of gypsum, the marmo bardiglio di Bergamo of statuaries; it takes a fine polish.

ANIL, nil. The plant from the leaves of which indigo is prepared. It grows in America.

ANIMALS, chemically considered, are chiefly composed of azot, carbon, hydrogen, and oxygen; and with these, phosphorus and limeforming the bony parts, sulphur, soda, magnesia, iron, &c., are frequently found combined in variable proportions. The analysis of animal substances is as yet very incom

plete and imperfect, but is now prosecuting, particularly in France, with considerable success.

ANIME, gum anime. A resinous substance, brought from America, used by perfumers, and by surgeons, to form plasters, which have been thought beneficial for nervous affections of the head.

ANNEALING. A process somewhat analogous in principle to tempering metals. Its object is to render substances, otherwise brittle, tough; and it is usually performed by cooling them gradually after they have been heated. ANNOTTO, anatto. ANTHRACITE.

Blind coal, Kilkenny coal, glance coal. A peculiar coal, which yields neither flame nor smoke, and leaves whitish ashes behind.

ANTHRANOTHION. A name given by M. Von Grotthus to the supposed base of sulphocyanic acid.

ANTIMONIATES. Compounds of antimonic acid and different bases. ANTIMONIC ACID, peroxide of antimony.

ANTIMONIOUS ACID, deutoxide of antimony, argentine flowers of antimony.

ANTIMONITES. Compounds of antimonious acid and different bases.

ANTIMONY. A peculiar undecompounded metal. The antimony of commerce is an ore consisting of sulphur and this metal.

mixture to the heat of a spirit lamp in a small glass globe with a short neck, or in a platina spoon. The mixture soon becomes liquid, and seems at first of a rose colour, then purple, then blue, and in an instant it catches fire, detonates, becomes dry, and of a fine green. The product spreads over the glass like small rolled up leaves of tea. A single sheet of paper will receive the whole of the eruption of the crater of this mimic chemical vol

cano.

ERRORS AMONG THE MASTERS; OR, DR. THOMPSON AND M. VAUQUELIN.

To the Editor of the Chemist. SIR,-Some of your readers who are deep in the study of chemistry may thank me for the following translation of some observations of M.Vauquelin, the celebrated French chemist, on a passage in Dr. Thompson's System of Chemistry They are contained in the Annales de Chimie et Physique for April 1824. I am, Sir,

Your obedient servant,
CRITICUS.

In Thompson's System of Chemistry, says M. Vauquelin, p. 311, (the passage is to be found at p. 273, vol. i. sixth edition,) it is stated: "When electric sparks are passed through phosphuretted hydrogen gas for some time, the phosphorus is deposited, and pure hydrogen gas remains; but the volume of the gas is not altered by this process. Hence it follows, that phosphuretted hydrogen gas consists of hydrogen gas holding a quantity of phosphorus in solution. This quantity is discovered by subtracting the specific gravity of hydrogen gas from that of phosphuretted bydrogen." Further on, at p. 275, he says:-" Hydrophosphoric gas may be procured by exposing phosphuretted hydrogen to the direct rays of the sun. A quantity of phosphorus is deposited, and the gas changed into hihy droguret of phosphorus. When sulphur is sublimed in this gas, the volume is doubled, and two volumes of sulphuretted hydrogen

gas are formed." An effect which, according to the same author, continues M. Vauquelin, takes place when potassium is heated in it. From this the conclusion is drawn that bihydroguret of phosphorus is composed of two volumes of hydrogen gas united to the same quantity of phosphorus as exists in one volume of phosphuretted hydrogen gas, and these two volumes are condensed into one. There is in this, as is very evident, a manifest contradiction. If phosphuretted hydrogen gas consists of hydrogen gas holding a quantity of phosphorus in solution, without being condensed, and if this gas is converted by the effect of the sun's rays, or by electricity, into bihydroguret of phosphorus without changing its volume, it is evident that the latter is also a solution of phosphorus in hydrogen, without condensation, and that there is no difference between these gases but in the quantity of phosphorus. In fact, in order to make the second part of the reasoning of Dr. Thompson correct, the phosphuretted hydrogen gas should be condensed to the half of its volume in becoming bihydroguret of phosphorus, which, according to Dr. Thompson's own statement, does not take place. This would be the first time, probably, that hydrogen gas was ever seen to condense its volume in parting with a solid body which it held in solution, though the contrary is frequently met with. It is, however, of some consequence to ascertain if the volume of the bihydroguret is doubled when sulphur is sublimed in it; for as it is ascertained that sulphuretted hydrogen gas contains a volume of hydrogen equal to its own volume, it must be admitted, that if the volume of bihydroguret was doubled by the sulphur, it must contain two volumes of hydrogen gas condensed in one; but this does not happen, as will be seen by what follows: - Experiment 1st. One hundred measures of phosphuretted hydrogen gas, exposed for some days to the influence of the sun, deposited phosphorus, and ceased to take fire in the air; the volume