bably from the fragments which floated in upon the breaking up of the great exterior mass. In the middle of March these ramparts were only 75 paces broad, in the beginning of May they were 500. These piles of ice resembled the houses of a great city, interspersed with apparent towers, steeples, and chimneys. The sailors, viewing with despair this position of the vessel, earnestly entreated permission to fit out the two boats, and in them to undertake the voyage homeward. The master at length agreed, provided there was no better prospect by the end of May. From the 20th to the 26th a north wind came on, and blew upon them a still greater quantity of ice; so that they no longer hesitated to begin their work, and to bring from the ship sails and cordage. The mere digging of the boats from under the snow was a most laborious task, and the equipment of them would have been next to impossible, but for the enthusiasm with which it was undertaken. By the 11th of June, they had the vessels fitted out, their clothes packed, and the provisions embarked. Then, however, they had to cut a way through the steeps and walls of ice which intervened between them and the open sea. Amid the extreme fatigue of digging, breaking, and cutting, they were kept in play by a huge bear which had come over the frozen sea from Tartary.

At length the crew having embarked all their clothes and provisions, set sail on the 14th with a westerly breeze. In the three following days they passed the Cape of Isles, Cape Desire, and came to Orange Isle, always working their way through much encumbering ice. As they were off Icy Cape, Barentz, long struggling with severe illness, and now feeling his end approach, desired himself to be lifted up, that he might take a last view of that fatal and terrible boundary, on which he gazed for a considerable time.

On the following day, the vessels were again involved amid masses of drift-ice, and were so forcibly struck, as well as squeezed between opposite fields, that the men had bid a final adieu to each other. Seeing, however, a body of fixed ice at a little distance, De Veer took a rope, and leaped from fragment to fragment, till he arrived on the firm surface. A communication thus formed, they landed first the sick, then the stores and provisions, and, finally, they drew the boats themselves upon the ice. During this detention, Barentz being informed of the severe illness of one Adrianson, said, that he himself was not far from his end. As he continued, however, conversing and looking on a chart of the voyage made by De Veer, it

was thought that his disease could not be so serious, till he pushed aside the chart, asked for a draught of water, and immediately expired. This event extremely affiicted the crews, both from their personal attachment to Barentz, and the loss of his skill in piloting the vessels.

The sailors, with some drift-wood, repaired the boats; the ice, however, was still close around, and they were struck with the fear that they would never escape from this bank, but must perish upon it. On the 22d, however, there appeared open sea at a little distance, and having dragged the boats over successive pieces of ice, they were again afloat. In the three following days they reached Cape Nassau, the ice frequently stopping them, but opening again like the gates of a sluice, and allowing a passage. On the 26th, they were obliged once more to disembark and pitch their tents on the frozen surface. On the opposite coast they saw immense herds of sea-cows, (walrus,) and the air darkened with numberless birds. While they were fast asleep in the tent, the sentinel called out, "Three bears! three tears!" The whole crew were instantly out; their muskets were charged only with small shot for birds; however, "these sweetmeats," though they could not inflict any serious wound, induced the monsters to turn, when one of them was pursued and killed. The dead bear was carried off in the mouth of one of the survivors to the most rugged parts of the ice, where the two devoured a large portion of his carcass.

The year was now advanced; the bright light of the sun and the occasional southwesterly breezes dissolved the ice, and gradually opened a way before them. It brought, however, dangers of a new clas The distinction between fixed and floating ice had now almost ceased, the former melting continually away. As they thought themselves lying secure on a large field, a body of icebergs came in from the open sea, struck and dashed it to pieces. The packages were separated from the boats, and several dropped into the water. It was laborious to scramble over the detached fragments to a place of safety, while the weighty articles sank into the softened ice, not without the greatest risk of falling to the bottom. For twelve hours the sailors floundered through this loose and broken surface before they could establish them- . selves on the field which was attached to the land.

The 2d of July was the finest day yet seen in Nova Zembla; and the weather continuing favourable, produced on the 7th an open sea, to which, with great labour,

the men succeeded in dragging the boats. From this time their progress, though often obstructed, was never entirely stopped. In several of the rocky bays they caught an immense number of birds, these poor animals not having yet learned to fear man, and allowing themselves to be taken by the hand. Near Admiralty Bay they saw two hundred sea-cows lying on a bank of ice, and attacked them; but these powerful animals advanced to the combat, snorting and blowing in so tremendous a manner, that, had not a fresh wind sprung up, the mariners might have been in a serious predicament; and they repented bitterly, amid so many inevitable evils, to have brought on themselves one so very unnecessary.

On the 28th, after passing the bay of St. Lawrence, when they approached to the southern extremity of Nova Zembla, the navigators discovered, with surprise and joy, two Russian vessels at anchor. They approached, and were received with the usual courtesy of that nation.-Edinburgh Cabinet Library, vol. i.

NOTES ON SIR HUMPHRY DAVY'S TWELFTH LECTURE, DELIVERED IN DUBLIN, NOVEMBER 29TH, 1810.

Sulphur and phosphorus in the Voltaic circle are negative.-Sulphur is positive to acid, and acid negative to sulphur.

Sulphur and phosphorus are non-conductors in a cold state: electricity only acts on them when in fusion. The electric spark passed through fluid sulphur in a glass tube, produced fire and light, and the emission of gas consisting of sulphuretted by drogen.

Both sulphur and phosphorus contain inflammable air; there is reason to expect a small quantity of oxygen in them. This is proved by potasium. Erper. A little tray of platina, put into an exhausted retort, with a bit of potasium and sulphur on the tray, kindles into light, by the heat of a candle, or lamp: hence the sulphur has oxygen; for if it had not, the hydrogen would weigh less after, than the loss of the sulphur and phosphorus in the combustion, which is not the case. Potasium and phosphorus, in an exhausted retort, do not inflame as sulphur: it forms a new compound in water, viz. acid of phosphorus, which gives phosphorus and hydrogen. The latter is proved by its inflammability, hence phosphorus contains some oxygen.

Oxygen, muriate of potash, and phosphorus, having the sulphuric acid poured to the bottom through a tunnel, burns under water,

Oxygen makes mercury a non-conductor; hydrogen makes charges of the electric spark take effect.

Phosphorus and sulphur, if free from hydrogen and oxygen, may become metals. Charcoal is an earthly alkali. The diamond is said to be pure carbon: it produces carbonic acid, by combustion with oxygen. Plumbago is the pure carbon. Diamond only relates to charcoal, as both stones and earths are metallic oxids. The diamond powder by combustion with potasium yielded oxygen, and became black like plumbago. All metals are comprised of charcoal and oxygen. Hence the diamond, which is a stone, forms a link in the chain, and is carbon by analogy.

All inflammable things are brought into combustion, either by oxygen or oxygenized muriatic acid.

Boracic and fluoric acids were not decomposed till lately by electricity. Boracic acid is a non-conductor, but by water it takes the electric charge; and when poured on a plate of platina, on the negative side was a dark inflammable substance which is a nonconductor, and prevents the perfection of the separation, but by burning this, boracic acid is reproduced, which is permeable to water, though not combined with it. The lecturer tried if potasium would aid the decomposition. He put it in a tube with moist boracic acid; it burned with a green light, reproducing potash, and the base of boracic acid, in a red heat. This borax being washed with salt and acid, became pure. It dissolves in acids, sulphuric gas, nitric gas, and combines with sulphur.

In a retort of oxygen gas, it burns and reproduces boracic acid.

This is a new matter, and a combination never formed before 1807: it hardens copper, and can be made of iron by white heat, but not pure.

The fluoric acid discovered by Scheele, is never pure; if made with lead, it has water combined; if with glass or silicious earth, by the electric spark it yields dense white fumes! With silex and borax it forms fluo-boracic, and by the spark fluosilex.

With potasium, the fluo-silex gas decomposes it, and makes a fawn-coloured base of fluoric acid.-Exper. A bit of potasium in an exhausted receiver, then filled with fluoric acid gas heat, makes combustion, which leaves the base behind.

A body which resists decomposition, is one whose combination is most attractive. Hence refractory bodies have the strongest play of affinity.

In the last lecture some persons conceived

that what was spoken of the combustion of sulphur or phosphorus with potasium, seemed to allow that the oxygen in them was the cause of combustion; that this is not the fact, a combustion of sulphur from iron barytes is made, clear of

oxygen.

Pure inflammable sulphur, without oxy gen in it, would produce combustion with potasium.- Exper. A little powder of arsenic with a bit of potasium, in an exhausted retort, produces combustion without any oxygen.

Heat and light are merely results of the intense energy of combination.

Oxygen and oxymuriatic acid gas, have more affinity for combustible bodies, than any other products; and hence appear the principal causes of combustion: but they are not exclusive causes; for any bodies, however destitute of their nature, that have much affinity for combination, will cause heat and light to appear.

Potash solution, heated in a retort with phosphorus, produces a gas that takes fire instantly on contact with the air.

In oxygen this gas is very brilliant. In oxymuriatic acid it burns green: it must be let in by small quantities, or it will explode. It gives out hydrogen, and leaves phosphate of potash. The oxymuriatic acid gas, leaves muriatic acid in combination. Sulphuretted hydrogen is decomposed by the electric spark, and deposits sulphur.

Exper. Eight hundred pair of plates communicate through a sphere of glass full of the gas; and the spark being excited by the carbon at the end of the wires, decomposition takes place with white fumes, which descend and deposit sulphur on the interior surface of the glass. In this manner several other gasses are decomposed.

This decomposition is made without electricity by potasium, and forms a new compound.

The sulphuretted hydrogen and potasium support combustion free of any oxygen, except that portion which the lecturer suspects to exist in all common sulphur and phosphorus, through defect of purification,

The combinations of hydrogen and charcoal are various, because they can be condensed in various proportions.

Hydrogen may take up twice its bulk of space, and be of course weaker; hence as carbonic acid can do the same, there may be two of hydrogen to one of carbon, or one of hydrogen to two of carbon, or an equal quantity of each; the latter mixture is the gas-light, which issuing from a tube, and being set fire to, burns as fast as it gets out.

Oxymuriate of potash and sulphur, or caustic, lime and salvolatile, produce, with ammoniacal gas, an elastic air, fatal to life. It is a volatile alkali; this gas supports combustion; and if infused into the flame of a candle, it increases its burning in combination with the carbonic acid gas of the wick.

Ammoniacal gas is decomposed by the electric spark in the manner before described; it affords the strongest alkali known.

The ammonia connected with the negative wire, in contact with mercury, forms an amalgam possessed of extraordinary powers.

The alkali is to be moistened. The mercury, in the common form of a globule of quicksilver, placed in the former, it swells to ten times its bulk, and becomes fixed, soft yet solid! This is an amalgam of the metal of ammonia with mercury, in the same manner as the metal of lime and other earths were procured by such amalgam. In air it decomposes; and the mercury and the ammonia are reproduced, the former in a globule; the latter shews its alkaline property, by turning yellow turmeric paper a bright brown.

If the mercury is weighed before and after amalgamation, it proves that 100th part of its weight caused the solidification. The amalgam in water gives ammonia and hydrogen gas, besides the mercury.

This amalgam is made without the Voltaic battery by potasium. First amalgamate a small bit of potasium with the mercury by gentle heat; then add the ammonia: in one moment the quicksilver is fixed! and if more mercury is added, it also swells and solidifies! -[Note. Mercury is equally fixed by frost; neither fixations are permanent. Query: From the equal action of the battery, and of potasium, which is a product of the battery, whether the new metals are more than the alkalies and earths imbued with a metallic transitory appearance, in consequence of the electric fire having passed through the copper and zinc, excited to oxidation in the weak muriatic acid which fills the trough? As there is no fire without fuel, can the electricity convey its metallic fuel to the earth, or salt be said to become a metal, any other than as petrified wood is called stone, or iron steeped in vitriol seems copper?] The metal of ammonia cannot be separated in a metallic state from the amalgam; the portion of ammonia metal is so small, that it is decomposed by a particle of moisture too small to be observed in the mercury; and if by distillation this water arises, it first decomposes the ammonia metal.

Professor Davy said, that he thought the analysis of ammonia will lead to future discoveries it may be, that hydrogen and nitrogen are elements in its composition, and the composition of all things, and by their respective preponderance raise or lower their states; but this is hypothesis. It is however certain, that all bodies are constant in their proportions to combination. This fact was first published by Higgins, (Lecturer of the Dublin Society), twenty years ago; but it has been nevertheless overlooked till lately, and other chemists now assume it as their own. From these grounds the lecturer thinks that the science of chemistry can be founded on arithmetical mathematics. This, he said, may be illustrated by the humble method of beads of several colours, for the several prime constituent parts in the most simple order, and he finds that it points out the nature of all bodies, not only simple, but the most compound.

If electricity is found to be as constant as chemistry in the arrangement of bodies, by the weight of their respective combination, the powers of affinity will have a mathematical certainty of result. This will be the dawn of a new era in the atomical philosophy, as well as in chemistry, which is now, the lecturer thinks, in the same infant state that astronomy was in the time of Galileo. And as that confusion was made order by the Newtonian system, so he looks forward in future times for some system of chemistry worthy of the grand scenes nature presents to us, for which modern chcmistry is inadequate.

The ancients generalized, without waiting for facts: let it not be so now. Let not human imagination erect systems for nature; but let nature erect a system for human imagination.

It is an unbounded field, prolific in national benefits, and enlarging human limits while it refines human nature. The German monk who deflagrated nitre, sulphur, and charcoal, took personal animosity from the soldier's breast, and, with a new art of war, founded a new moral feeling.

In a country advancing in civilization, the great and permanent objects of nature which the researches of philosophy afford the mind, and the arts afford the body, give a beneficial occupation to people, whose energies may otherwise be directed on the transitory politics of human opinion. Numbers of people, who cannot ever conceive the principles of science, may take the most effectual part in them, like the man who conducts a steam-engine, or the artificer of an electric conductor. In times of peril, a country may be invincible by its

science and arts. The Greek fire destroyed an invading fleet. Optics produced the burning glass. The spring and lever actuated the catapulta; but these are all exceeded by modern arts-and new sources of defence are open, more legitimate than the principles of war, by which an universal empire is at this time (1810) attempted.

The observation of divine wisdom in the Creator, must lead the student in science to contemplate the perfection of that Intelligence, which formed and supports all.

Ignorance produces sloth and inactivity, but science is the parent of industry; and while science is patronized in this city, the best results may be expected in the example and instruction furnished by superior rank supplying information on subjects of importance to the welfare of all classes of the community.

VARIETY AND PROPERTIES OF IVORY.

ALTHOUGH this valuable article is very generally known, the following particulars respecting its source, nature, and character, can hardly fail to prove interesting to most of our numerous readers. Almost every one knows that ivory is procured from the tusks, or large conical tecth, in the upper jaw of the elephant; but it may be necessary to add, that the name is sometimes given to the teeth of the sea unicorn, the morse and the hippopotamus.

The elephants' tusks from Africa are in general preferred by the dealers in this article; they generally run considerably larger; but it is a common opinion, that the ivory from Ceylon is less liable to turn yellow when exposed to the action of the atmosphere, whence it is sold at a higher price than the other. By far the greatest part of this merchandise is brought from Africa, and a part of Guinea, which has furnished the greatest quantity of it, has obtained the name of the Ivory Coast; the tract of coast from Cape Palmas to Apollonia, or Trespunta, is more particularly known by this appellation. But the principal market for some time past appears to have been at the, east coast of Africa, where the ivory is supposed to be found of superior quality; indeed, the English merchants at Surat pay a greater price for the tusks furnished by this part of the coast than for such as are brought from any other part of Africa.

The best tusks are those that are least curved, without spots, and most solid towards the base. Some writers on this subject pretend that such elephants as inhabit swampy places, generally produce blue, spongy, and knotty tusks, in every respect

inferior to those of elephants living in hilly countries, or on dry plains. The Ethiopian elephants' tusks, according to Paul Lucas, are furnished with larger cavities, and are therefore less esteemed.

Elephants' teeth constitute a very important article of commerce. Labat computed the quantity of ivory annually imported into France in his time, by the Senegal company, to be 500 quintals, or 50,000 pounds. In 1784, the number of tusks imported into Nantes was 744, besides 360 pounds weight; and into Havre de Grace, in the same year, 435 tusks and 1805 pounds, and into Bourdeaux 5999 pounds. In the following year 3007 pounds and 471 tusks were imported into Nantes; in 1787, 16,184 pounds and 395 teeth; and into Havre de Grace 3784 pounds.

In an account which the house of commons ordered to be given in, of the quantities of the principal articles in the nature of raw materials, imported and used in the manufactures of Great Britain for twelve years preceding the year 1799, we find the following, respecting the importation of elephants' teeth; viz.

The component parts of ivory being the same as those of bones (viz. phosphate of lime combined with a gelatinous substance,) and differing only with regard to texture, hardness, and whiteness, the preparations it undergoes in the arts are equally applicable to the bones of animals. The whiteness which ivory acquires depends chiefly on the degree of dryness it has obtained. When yellow, its gelatinous matter is altered by the air, and appears to be combined with the oxygen of the atmosphere. Oxygenated muriatic acid will restore it to its original whiteness. Those employed in working ivory, distinguish the white and the green. The former is known by the whitish or lemon coloured rind of the tusks, the other by the brown and blackish. The green ivory (so called from a greenish or faint olive colour pervading its substance) is preferred, it be ing of a closer texture, and known soon to exchange its green hue for the most beautiful white, which is less liable to turn yellow. This green ivory is, however, more brittle

than the other.

Heat cannot be made use of for making ivory pliant, though it is rendered softer by being exposed to that agent. It is divided

by the saw; sometimes (for delicate work) under water, in order to prevent its being heated or rent in the operation. It is polished with pumice and tripoli. Ivory has been said to become soft by being placed in mustard; but that end is attained with greater certainty by steeping it in some diluted mineral acid. Both ivory and common bones become also soft by being immersed in an alkaline lye made of soda and quick-lime.

By burning this substance in closed vessels, and afterwards levigating it with water on a porphyry slab, we procure what is called black ivory, much used for painting, and other purposes that require a very intense velvet-like black colour.

Cuvier, in examining the varieties of tusks, and the differences remarked in this respect among elephants, observes, that their texture exhibits no important difference. It always presents, upon its transverse section, those streaks which proceed like an arc of a circle from the centre to the circumference, and form, in growing, curvilinear lozenges which occupy the whole disk, and which are more or less broad, and more or less perceptible to the eye. This character, common to all elephant ivory, and depending immediately on the pores of their pulpy nucleus, is not to be found in the tusks of any other animal. It is to be seen in all fossil tusks, and it refutes the opinion of Leibnitz, adopted by some other writers, and even by Linnæus, that the mammoth horns might have belonged to the Trichecus rosmarus. The tusks of these animals, however, seem wholly composed of small round accumulated grains.

The size of tusks varies according to the species, sexes, and varieties; and as they are growing all their lives, age, more than any thing else, influences their dimensions. The African elephant, as far as we are able to ascertain, has very large tusks in both sexes. The African female, seventeen years old, the skeleton of which is in the museum of Paris, has larger tusks than any male or female Indian elephant of the same size that we are acquainted with. It is from Africa we receive the most ivory, and the greater number of tusks; and they are also harder and whiter than any others. But our limited knowledge is confined to the elephants of the western coasts, and to those of the south of Africa. We are ignorant if those of the eastern shores resemble them in every thing, and if there be any varieties in the interior. We know from Pennant, however, that the coast of Mosambique furnishes tusks ten feet long, being the largest ever known. In the Indian species there are more varieties