meteors. These vapours are therefore blended with aqueous, aerial, sulphurous and terrestrial particles, &c. and it is the solid and earthy particles which form the mud or slime we are now speaking of. When rain water is suffered to rest, a sediment is formed at bottom; and having collected a quantity, if it is suffered to stand and corrupt, it produces a kind of mud which falls to the bottom of the vessel. Dew produces much more of this mud than rain water, which is greasy, unctuous, and of a reddish colour.

The first strata of the earth is composed of this mud, mixed with perished vegetable or animal parts, or rather stony and sandy particles. We may remark that almost all land proper for cultivation is reddish, and more or less mixed with these different matters; the particles of sand or stone found there are of two kinds, the one coarse and heavy, the other fine and sometimes impalpable. The largest comes from the lower strata loosened in cultivating the earth, or rather the upper mould, by penetrating into the lower, which is of sand and other divided matters, and forms those earths we call fat and fertile. The finer sort proceeds from the air, and falls with dew and rain, and mixes intimately with the soil. This is properly

the residue of the powder, which the wind continually raises from the surface of the earth, and which falls again after having imbibed the humidity of the air. When the earth predominates, and the stony and sandy parts are but few, the earth is then reddish and fertile: if it is mixed with a considerable quantity of perished animal or vegetable substances, it is blackish, and often more fertile than the first; but if the mould is only in a small quantity, as well as the animal or vegetable parts, the earth is white and sterile, and when the sandy, stony, or cretaceous parts which compose these sterile lands, are mixed with a sufficient quantity of perished animal or vegetable substances, they form the black and lighter earths, but have little fertility; so that according to the different combinations of these three different matters, the land is more or less fecund and differently coloured.

To fix some ideas relative to these stratas; let us take, for example, the earth of Marly-la-ville, where the pits are very deep: it is a high country, but flat and fertile, and its strata lie arranged horizontally. I had samples brought me of all these strata which M. Dalibard, an able botanist, versed in different sciences, had

dug under his inspection; and after having proved the matters of which they consisted in aquafortis, I formed the following table of them.

The state of the different beds of earth, found at Marly-la-ville, to the depth of 100 feet.

Feet.In.
1. A free reddish earth, mixed with much mud, a very small quantity of vitrifiable sand, and somewhat more of calcinable sand130
2. A free earth mixed with gravel, and a little more vitrifiable sand26
3. Mud mixed with vitrifiable sand in a great quantity, and which made but very little effervescence with aquafortis30
4. Hard marl, which made a very great effervescence with aquafortis20
5. Pretty hard marl stone40
6. Marl in powder, mixed with vitrifiable sand50
7. Very fine vitrified sand16
8. Marl very like earth mixed with a very little vitrifiable sand36
9. Hard marl, in which was real flint36
10. Gravel, or powdered marl10
11. Eglantine, a stone of the grain and hardness of marble, and sonorous16
12. Marly gravel16
13. Marl in hard stone, whose grain was very fine16
14. Marl in stone, whose grain was not so fine16
15. More grained and thicker marl26
16. Very fine vitrifiable sand, mixed with fossil sea-shells, which had no adherence with the sand, and whose colours were perfect16
17. Very small gravel, or fine marl powder20
18. Marl in hard stone36
19. Very coarse powdered marl16
20. Hard and calcinable stone, like marble10
21. Grey vitrifiable sand mixed with fossil shells, particularly oysters and muscles which have no adherence with the sand, and which were not petrified30
22. White vitrifiable sand mixed with similar shells20
23. Sand streaked red and white, vitrifiable and mixed with the like shells10
24. Larger sand, but still vitrifiable and mixed with the like shells10
25. Fine and vitrifiable grey sand mixed with the like shells86
26. Very fine fat sand, with only a few shells30
27. Brown free stone30
28. Vitrifiable sand, streaked red and white40
29. White vitrifiable sand36
30. Reddish vitrifiable sand150
————
Total depth1010
————

I have before said that I tried all these matters in aquafortis, because where the inspection and comparison of matters with others that we are acquainted with is not sufficient to permit

us to denominate and range them in the class which they belong, there is no means more ready, nor perhaps more sure, than to try by aquafortis the terrestrial or lapidific matter: those which acid spirits dissolve immediately with heat and ebullition, are generally calcinable, and those on which they make no impression are vitrifiable.

By this enumeration we perceive, that the soil of Marly-la-ville was formerly the bottom of the sea, which has been raised above 75 feet, since we find shells at that depth below the surface. Those shells have been transported by the motion of the water, at the same time as the sand in which they are met with, and the whole of the upper strata, even to the first, have been transported after the same manner by the motion of the water, and deposited in form of a sediment; which we cannot doubt, as well by reason of their horizontal position, as of the different beds of sand mixed with shells and marl, the last of which are only the fragments of the shells. The last stratum itself has been formed almost entirely by the mould we have spoken of, mixed with a small part of the marl which was at the surface.