pact masses, whose fracture is dull, splintery and sometimes though, rarely conchoidal. It is opaque, at the edges; its more common color is bluish or grey; it is seldom a pure carbonate, but contains from two, to ten per cent. of silex. Some of these limestones, are so impure, that they melt, rather than burn into lime. Our limestone is of a recent formation, generally, and may be called, shell limestone. It is either found in hills, with rounded summits, or under a level country. Its strata are often thin, lying between strata of clay slate and is composed almost wholly of sea shells. This limestone often presents fissures and rents, holes and caves.

In Kentucky, are caves of vast extent, and one of them, has been explored twenty-one miles, under ground, called the mammoth cave, in the vicinity of Green river. We have but a few caverns, in our limestone region, and they are of no great extent.

In Highland county, are some caverns, near the Sinking spring, and a few sharks' teeth were found in it, several years since. The most valuable bed of limestone, now known to exist, in this state, is situated five miles above Columbus, on the main branch of the Scioto river, the property of Mr. S. G. Renick. Large blocks are constantly taken from it, of any desirable size, for pillars, and for fronts of houses. It is a durable and beautiful building stone, and bears a tolerable good polish. In Renick's marble quarry is stone sufficient, to last many centuries, for the Scioto country.

Our limestone, furnishes an excellent lime, for building. Its calicination is now effected by wood, but the heat should not be great.

Count Rumford, has invented an oven for burning lime. It is a high cylinder, with the hearth at the side, and at some distance above the base. The fire burns, with a reflected, or inverted flame. The lime is taken out at the bottom, while fresh additions of limestone are made at the top, so as to keep the oven constantly heated. Limestone, either moistened or just dug, calcines easiest. If dry, it should be moistened when put into the kiln.

MORTAR.

We have a few remarks, on making it. This is commonly a mixture of sand and slacked lime. When sand cannot be had, pulverised dry clay or brick-dust, will answer as well.

To the sand and slacked lime, if iron dust, or manganese be added, a cement may be made, which will harden under water. With such a cement, cisterns may be made, tan vats, and cellar walls, that will answer many useful purposes.

Compact lime, is often used, as a manure, and our shell lime, is the best for that purpose. Sometimes, the stone is only pulverised, sometimes it is burnt. Many of our marbles that are full of shells, are very beautifully variegated, with spots of different forms and colors. Sand and emery, putty and tin filings, with water, are employed in polishing this limestone. As yet, we have discovered but few beds, of this stone, which are used as marbles. Time and further research may discover to us, other marbles, at no distant day, in our limestone region. It is quite probable, that the best marbles lie deeper in the earth, than we have, as yet, sought for them.

Southwest of Springfield, on the road to Dayton, is a limestone of peculiar appearance. Its structure and aspect resemble, those in western New York, where gypsum and limestone abound. That near Springfield deserves examination, by some one, acquainted with those minerals of western New York. It is quite possible, that the limestone near Springfield may answer a good purpose for backs of chimneys, and ought to be tried, by exposure to great heat, and, by then throwing it into water, while thus heated. That it is an excellent limestone, for producing mortar, we doubt not, and by mixing with it a proper proportion of sand, it may produce a cement that will harden under water.

ORGANIC REMAINS,

Found in the limestone formation, in the Miami country and above Columbus, on the Scioto river, in Renick's quarry. R. Buchanan furnished us with the names of them.

The organic remains found in Tennessee and Kentucky, and probably in Ohio, not mentioned above, viz:

Of Favosites, we have a great many along the Scioto

valley.

PRIMITIVE ROCKS.

These are discovered, as soon as we have ascended the second ridge, south of lake Erie, as we travel southwardly. They consist of granite, sienite, black mica, and indeed every variety of mica slate, gneiss, and all the primitive rocks of this continent. They occur in amorphous masses, abraded, and smoothed, by friction, and show conclusively, that they are out of place, and are unconnected with any other rocks in, or near, where they now lie. They are generally, at an elevation of about seven hundred feet, above the present surface of the ocean. But where the earth has been worn away by some stream of water, near them, they have, in some instances, been undermined, and have fallen down, on a lower level. These boulders, are found in large masses, covering in some places, several acres, reposing on the north sides of hills, of a diluvial deposite. They are rarely found on the southern ends of hills, unless removed thither, by some more recent revolution, than the one which deposited them originally in this country. These primitive rocks, we have seen all along the southern shores of the northern lakes, from the east end of lake Ontario, to the western side, of the southern end of lake Michigan. They are uniformly found at about the same height, unless removed by some force more recent, apparently, than that, which, originally deposited them in this region. From east to west, they extend, at least eight hundred miles, in a right line. Their elevation is everywhere, nearly the same, above the present surface of the ocean, and they are most numerous, on the northern ends of hills, pointing a little east of north-about three points of the compass.

When we say, that these rocks are found, thus, in a line extending from the lower end of lake Ontario, to the western side of the southern end of lake Michigan, we do not say, that these rocks are not found, east and west of these limits. But, thus far, we have seen them, and have carefully examined them, in person, and have noticed, carefully, every circum

stance attending them. We saw none of them, west of lake Michigan, between that lake, and the Upper Mississippi.

They are found, in some instances covering half an acre of surface and sometimes, three acres. There is such a deposite, resting on the northeastern end of a diluvial hill, just south of the road leading from Dayton to Cincinnati, about three miles, perhaps less than three miles, southerly of Dayton. There is such a deposite, in the northwestern corner of the town plat of Circleville, partly covered with earth, by some later event than the one which brought these rocks here. There was, when this town was first settled, such a deposite, on the north side of the great mound, in this town. These rocks are found in considerable numbers in Madison county, resting on the surface of that elevated, diluvial plain.

Considerable numbers, may now be seen, resting on the bed of the Olentangy creek, several miles below the town of Delaware between that town and Worthington. They have been undermined by the washing away, of the clay slate under them.

These rocks, have been often used, for millstones and sometimes, one boulder, is so large, as to make several mill stones. These are granitic rocks. They are used too, for underpinnings of houses and barns. The court-house in Madison county, stands on these old rocks.

By what means, were these rocks, transported here, and left, on our surface? That they have been brought here, long since the revolution, which deposited our sandstone and slaty rocks, of secondary formation; seems evident, from the fact, that they rest on the surface of a diluvial deposite of rolled pebbles. This diluvial deposite of pebbles, &c. is more recent than the sandstone and slate rocks. It seems evident, too, that the force which transported our primitive rocks here, was not so great as the one which transported the rounded pebbles, otherwise, the large boulders would have been whirled around the hills, and left at the southern ends of them.

Northern navigators, often tell us, of iceberges, floating in polar seas, with rocks, imbedded in them. We see the same