brownish, and hyacinth-brown, with a slight tinge of green. In the interior flame the colour passes from yellow-green, through yellow-brown and brown-red, to black; and if the proportion of acid be large, it acquires a metallic lustre, like the sulphuret, which sometimes remains after the glass has cooled. Molybdic acid is but little dissolved by borax. In the exterior flame the glass acquires a grey-yellow colour. In the interior flame a quantity of black particles is precipitated from the clear glass, and leaves it almost colourless when the quantity of molybdenum is small, and blackish when the proportion is larger. If to a glass formed of this acid and microcosmic salt a little borax be added, and the mixture fused in the exterior flame, the colour becomes instantly reddish-brown; in the interior flame the black particles are also separated, but in smaller quantity. By long continued heat the colour of the glass is diminished, and it appears yellower by the light of a lamp than by day-light. This acid is not reduced by soda in the interior flame.

Tungstic Acid becomes upon the charcoal at first brownishyellow, is then reduced to a brown oxide, and lastly becomes black without melting or smoking. With microcosmic salt it forms in the interior flame a pure blue, glass, without any, violet tinge; in the exterior flame this colour disappears, and reappears again in the interior. With borax, in the internal flame, and in small proportion, it forms a colourless glass, which, by increasing the proportion of the acid, becomes dirty-grey, and then reddish. By long exposure to the external flame it becomes transparent, but as it cools it becomes muddy, whitish, and changeable into red when seen by day-light. It is not reduced.

Oxide of Tantalum undergoes no change by itself, but is readily fused with microcosmic salt and with borax, into a clear colourless glass, from which the oxide may be precipitated by heating and cooling it alternately. The glass then becomes opaque, and the oxide is not reduced.

Oxide of Titanium becomes yellowish when ignited in a spoon, and upon charcoal dark brown. With microcosmic salt it gives in the interior flame a fine violet-coloured glass with more of blue than that from manganese. In the exterior flame this colour disappears. With borax it gives a dirty hyacinth colour. Its combinations with soda have not been examined.

Oxide of Cerium becomes red-brown when ignited. When the proportion is small it forms with the fluxes a clear colourless glass, which by increasing the proportion of oxide becomes yellowish-green while hot. With microcosmic salt, if heated a long time in the internal flame, it gives a clear colourless glass. With borax, under similar circumstances, it gives a faint yellow-green glass while warm, but is colourless when cold. Exposed again for some time to the external flame, it becomes reddish-yellow, which colour it partly retains when cold. If two

transparent beads of the compound with microcosmic salt and with borax be fused together, the triple compound becomes opaque and white. Flies off by reduction?

Oxide of Uranium. The yellow oxide by ignition becomes green or greenish-brown. With microcosmic salt in the interior flame it forms a clear yellow glass, the colour of which becomes more intense when cold. If long exposed to the exterior flame, and frequently cooled, it gives a pale, yellowish, red-brown glass, which becomes greenish as it cools. With borax in the interior flame a clear, colourless, or faintly-green glass, is formed, containing black particles, which appear to be the metal in its lowest state of oxidation. In the exterior flame this black matter is dissolved if the quantity be not too great, and the glass becomes bright yellowish-green, and after further oxidation yellowish-brown. If brought again into the interior flame, the colour gradually changes to green, and the black matter is again precipitated, but no further reduction takes place.

Oxide of Manganese gives with microcosmic salt in the exterior flame a fine amethyst colour, which disappears in the interior flame. With borax it gives a yellowish hyacinth-red glass.

When the manganese from its combination with iron, or any other cause, does not produce a sufficiently intense colour in the glass, a little nitre may be added to it while in a state of fusion, and the glass then becomes dark-violet while hot, and reddishviolet when cool: is not reduced.

Oxide of Tellurium, when gently heated, becomes first yellow, then light-red, and afterwards black. It melts and is absorbed by the charcoal, and is reduced with a slight detonation, a greenish flame, and a smell of horse-radish. Microcosmic salt dissolves it without being coloured.

Oxide of Antimony is partly reduced in the exterior flame, and spreads a white smoke on the charcoal. In the interior flame it is readily reduced by itself, and with soda. With microcosmic salt and with borax it forms a hyacinth-coloured glass. Metallic antimony, when ignited on charcoal, and remaining untouched, becomes covered with radiating acicular crystals of white oxide. Sulphuret of antimony melts on charcoal, and is absorbed.

Oxide of Bismuth melts readily in a spoon to a brown glass, which becomes brighter as it cools. With microcosmic salt it forms a grey-yellow glass, which loses its transparency, and becomes pale, when cool. Add a further proportion of oxide, and it becomes opaque. With borax it forms a grey glass, which decrepitates in the interior flame, and the metal is reduced and volatilized. It is most readily reduced by itself on charcoal. Oxide of Zinc becomes yellow when heated, but whitens as it cools. A small proportion forms with microcosmic salt and with borar a clear glass, which becomes opaque on increasing the quantity of oxide. A drop of nitrate of cobalt being added to

the oxide, and dried and ignited, it becomes green. With soda in the interior flame it is reduced, and burns with its characteristic flame, depositing its oxide upon the charcoal. By this process zinc may be easily detected even in the automolite. Mixed with oxide of copper, and reduced, the zinc will be fixed, and brass be obtained. But one of the most unequivocal characters of the oxide of zinc is to dissolve it in vinegar, evaporate the solution to dryness, and expose it to the flame of a lamp, when it will burn with its peculiar flame.

Oxide of Iron produces with microcosmic salt or borax in the exterior flame, when cold, a yellowish glass, which is blood-red while hot. The protoxide forms with these fluxes a green glass, which by increasing the proportion of the metal passes through bottle-green to black and opaque. The glass from the oxide becomes green in the interior flame, and is reduced to protoxide, and becomes attractable by the magnet. When placed on the wick of a candle, it burns with the crackling noise peculiar to iron.

Oxide of Cobalt becomes black in the exterior, and grey in the interior flame. A small proportion forms with microcosmic salt and with borax a blue glass, that with borax being the deepest. By transmitted light the glass is reddish. By farther additions of the oxide it passes through dark blue to black. The metal may be precipitated from the dark blue glass by inserting a steel wire into the mass while in fusion. It is malleable if the oxide has been free from arsenic, and may be collected by the magnet; and is distinguished from iron by the absence of any crackling sound when placed on the wick of a candle.

Oxide of Nickel becomes black at the extremity of the exterior flame, and in the interior greenish-grey. It is dissolved readily, and in large quantity, by microcosmic salt. The glass, while hot, is a dirty dark red, which becomes paler and yellowish as it cools. After the glass has cooled, it requires a large addition of the oxide to produce a distinct change of colour. It is nearly the same in the exterior and interior flame, being slightly reddish in the latter. Nitre added to the bead makes it froth, and it becomes red-brown at first, and afterwards paler. It is easily fusible with borax, and the colour resembles the preceding. When this glass is long exposed to a high degree of heat in the interior flame, it passes from reddish to blackish and opake; then blackish grey, and translucent; then paler reddish-grey, and clearer; and, lastly, transparent; and the metal is precipitated in small white metallic globules. The red colour seems here to be produced by the entire fusion or solution of the oxide, the black by incipient reduction, and the grey by the minute metallic particles before they combine and form small globules. When a little soda is added to the glass formed with borax, the reduction is more easily effected, and the metal collects itself into one single globule. When this oxide contains iron, the

glass retains its own colour while hot, but assumes that of the iron as it cools.

Oxide of Tin in form of hydrate, and in its highest degree of purity, becomes yellow when heated, then red, and when approaching to ignition black. If iron or lead be mixed with it, the colour is dark-brown when heated. These colours become yellowish as the substance cools. Upon charcoal, in the interior flame it becomes and continues white; and, if originally white and free from water, it undergoes no change of colour by heating. It is very easily reduced without addition, but the reduction is promoted by adding a drop of solution of soda or potash.

Oxide of Lead melts, and is very quickly reduced, either without any addition, or when fused with microcosmic salt or borax. The glass not reduced is black.

Oxide of Copper is not altered by the exterior flame, but becomes protoxide in the interior. With both microcosmic salt and borax it forms a yellow-green glass while hot, but which becomes blue-green as it cools. When strongly heated in the interior flame it loses its colour, and the metal is reduced. If the quantity of oxide is so small that the green colour is not perceptible, its presence may be detected by the addition of a little tin, which occasions a reduction of the oxide to protoxide, and produces an opaque, red glass. If the oxide has been fused with borax, this colour is longer preserved; but if with microcosmic salt, it soon disappears by a continuance of heat.

The copper may also be precipitated upon iron, but the glass must be first saturated with iron. Alkalies or lime promote this precipitation. If the glass containing copper be exposed to a smoky flame, the copper is superficially reduced, and the glass covered while hot with an iridescent pellicle, which is not always permanent after cooling. It is very easily reduced by soda. Salts of copper, when heated before the blow-pipe, give a fine green flame.

Oxide of Mercury before the blow-pipe becomes black, and is entirely volatilized. In this manner its adulteration may be discovered.

The other metals may be reduced by themselves, and may be known by their own peculiar characters.

ARTICLE X.

On the Height of the Himalaya Mountains.

IN the proceedings of the Royal Academy of Sciences at Paris, inserted in the last number of the Annals, is an account of a memoir by Alex. Von Humboldt "On the Height of the Mountains of India." It is there stated that "the 12th volume

of the Asiatic Researches will give us important information on the subject." The Editors lose no time in presenting to their scientific readers the following paper:

On the Height of the Himalaya Mountains: abstracted from a Paper by H. T. Colebrooke, Esq. inserted in the Asiatic Transactions, Vol. XII.

The chain of the Himalaya mountains, constantly covered with snow, is visible from Patna, on the Ganges, and from other places in the plains of Bengal, at the distance of at least 150 geogr. miles, forming a continued chain bearing to the E. of N., and extending through more than two points of the compass, and in clear weather appearing like white cliffs with a very distinctly defined outline.

The continuation of the same chain of mountains divides Butan from Tibet, and is distinctly visible from the plains of Bengal, a distance, calculated from the observations made by Captain Turner on his journey to Tisholumbo, of from 165 to 200 geogr. miles. Now it requires an elevation exceeding 28,000 feet for an object to be barely discernible in a mean state of atmospherical refraction at so great a distance as that last mentioned.

The late Lieut. Col. Colebrooke, while in Rohilkhand, completed two observations: one taken at Pilibhit, where the elevation of a peak distant, 114 English miles (according to bearings from two stations, the distance between which was measured) was found to be 1° 27': the other at Jethpur, where the elevation of the same peak, distant 90 English miles, was observed to be 2° 8'. From these elements, allowing of the intercepted arc for terrestrial refraction, the peak observed by Lieut. Col. Colebrooke must have an elevation equal to about 22,000 feet above the level of the plains of Rohilkhand. This allowance of

of the intercepted arc is deduced from Major Lambton's observations in the peninsula of India, according to which the refraction was found to vary from to

Colonel Crawford, during a long sojourn at Cat'hmandu in 1802, took the angles of several selected points, of which he determined the distances by trigonometrical measurement, having taken the bearings from various stations in the valley of Nepal, the relative situations of which were ascertained by a trigonometrical survey proceeding from a base of 852 feet, carefully measured four times, and verified by another base of 1582 feet, measured twice. The positions of the same mountains_were also settled by observations of them made in the plains of Bahar in the progress of the great survey.

The angles of elevation of the mountains above the stations of Sambhu and the Queen's Garden, near Cat'hmandu, were taken with an astronomical sextant and an artificial horizon. Among the most remarkable is an observation of a mountain pointed out