it comes up in bubbles, the petrifaction becomes of a round shape, as if the bubbles of a spring had all at once been arrested in their play, and transformed to stone.

The stone produced in this manner is brittle, transparent, and sometimes beautifully streaked with green, red, and copper-coloured veins. It can be cut into great slabs, and takes a good polish. Not much of the stone has been carried away lately. Some immense slabs still remain, which were cut by the great Nadir Shah, and which show what he intended to do. This stone is looked upon quite as an article of luxury, so that none but the king, his sons, or very great men are allowed to dig it out. Though I did not bring home a piece of Noah's ark, I have brought a bit of this stone. Here it is.

F. How curious it is to think that this once was water! Uncle, what will you have made with it?

U. O. I don't know.

There is another class of curious products from the water, which is found in great plenty in Persia and on its borders. We may call it generally" bitumen," and say that it is generally found floating on the top of the water in

wells. But the term bitumen comprehends a number of apparently different substances, from a perfectly liquid to a perfectly solid state. The liquid bitumen is called naphtha, and the solid bitumen is called asphaltum. But all the bitumens have this in common, that they readily take fire when flame is applied, and burn until all, or nearly all, their substance is consumed. The most liquid is of a light colour, or whitish yellow; but the thicker sorts are black, and are more common than the other. They are frequently found floating on water; but I do not suppose that water has anything to do with producing them; for they are often found in pits where there is no water, and appear to ooze from the ground equally into pits or wells. The white naphtha is, however, generally found floating upon the water like oil, and it is collected and used as oil for lamps. It gives a beautiful clear flame, which is not very hot; it is thus a trick of the Persian fire-eaters to let a piece of cotton that has been dipped in it, blaze away in their mouths. The people have a great opinion of the medical virtues of this naphtha, and in certain complaints take it internally, and in certain others apply it outwardly. The black

bitumen is not so pure or scarce. It emits a strong smell when burnt, and in many respects resembles pitch. The people collect great quantities of it, and apply it to many uses. It is used for light and firing near the places where it is found. In preserving it for this purpose, they keep it under ground in earthenware jars, at a distance from their houses, to prevent any accident from its taking fire, which it is very apt to do. They also use it for much the same purposes as we use pitch and tar, such as to prevent iron from rust, and to smear the outsides of boats. Besides this, it is employed much in the same manner as we would employ sheet-lead, to line baths and cisterns. In the ancient city of Babylon, it was used to cement together the bricks of which the houses were built. They were particularly careful to do this at the lower part of the buildings, because this cement united the bricks so firmly that it was impossible for any water to soak through the walls. The wells, both of the white and black bitumen, bubble up very much, particularly when the weather is hazy. Sometimes they overflow, and the bitumen runs in a stream along the ground: in this case it often takes fire, and near Baku, on the

Caspian, it then rushes flaming to the sea, and continues to burn upon the water.

Jane. But how can it take fire, Uncle? Does anybody put a candle to it?

U. O. That is well asked; for it reminds me to tell you that in the neighbourhood of bitumen springs, the ground is sometimes on fire. This is the case at Kerkook in Koordistan, and at Baku. At the former place, there is one hill on the flat top of which there are about a hundred holes, from each of which a beautiful clear flame issues, without smoke, but smelling strongly of sulphur. I remember that I pushed my walking-stick into the ground, and immediately a flame burst out at the hole I had made. The similar fires at Baku are still more interesting. The whole country around has sometimes the appearance of being covered with flame; and it often appears as if large masses of fire were rolling down from the mountains with incredible speed. In the midst of this land, which they consider holy, the fire-worshippers have a sort of temple; and several houses have been built in the neighbourhood.

F. I wonder they are not afraid of having their houses burnt down.

U. O. They build their houses there on purpose to have the benefit of the fire. To smother the flame, they cover the ground within their walls by a thick bed of earth, and when they want a fire to dress their meals, or for any other purpose, they have only to make a cut in the floor. Through this cut a gas escapes, and if they apply a light to it, a strong and beautiful flame bursts up. They have only to stop up the hole, when they no longer want the fire. The stream of air from the opening, is very plainly felt before the fire has been kindled and after it has been put out. I have heard of people who have carried away some of the earth, and have been greatly disappointed to find that it would not take fire. They now know better, and carry away leathern bottles full of the gas instead, more, of course, for curiosity than for use. As this inflammable air is only found near places which afford bitumen, I suppose it is produced from it under the ground, and escapes wherever it can find an opening.

H. Is bitumen found in any other countries, Sir?

U. O. Oh, yes ! It is found, in one or other of its forms, in most parts of the world, but