The following table shows the results of tests of Colorado sand

stone, made for the State Capitol and given in "U. S. Mineral Resources" for 1886:

Although limestone as well as sandstone is a sedimentary rock, it differs from it very much in its formation.

Water flowing down from a rough mountainous country carries with it a large amount of matter both in solution and suspension. As the stream reaches any large body of still water its velocity gradually decreases and that portion in suspension is deposited, the coarser and heavier near the shore and the finer farther out.

Calcareous matter as a rule, being soft, is generally fine and is borne from a distance and finally deposited as silt. All waters flowing as above contain a considerable quantity of lime in solution which, being in part precipitated, serves to consolidate the silt. From this same source certain marine animals derive their supply

for their shells. Upon the death and decomposition of the animal life the shells and corals are left and, breaking up, in time form calcareous banks which later on become beds of limestones of more or less fragmental nature.

The theory of the formation of oolitic varieties is somewhat different. It is supposed that certain fragments of calcareous matter have been deposited upon the bottom of some ancient sea, and that they were kept in motion by the action of the waves or some other force, preventing their solidification. If, then, the lime in solution should from any cause become too much for the absorption of the marine animals, it would be precipitated, and would form around the fragments, which, being in motion, would become approximately spherical in shape. But as the precipitation continues the interstices become filled and beds of solid stone are formed having the appearance peculiar to this variety.

Both of the above formations are generally in well-defined beds nearly level when not disturbed by any subsequent force. When, however, as often happens, the strata are found at all angles with the horizontal, they have been acted upon by some of the forces so frequent during the formation of the earth's crust.

In the course of time some of these beds may be broken up into fragments comparatively small and after having settled into a permanent position and again consolidated by the further deposits of lime or iron oxides in the interstices of the fragments. It is thus that the metamorphic limestones are formed.

Limestones differ greatly in structure from the variety highly charged with fossils to the hard compact rocks denser and heavier than granite.

They also vary in color according to the iron and carbonaceous compounds that may be present.

As calcite crystallizes so readily, few limestones are entirely amorphous, but range gradually from the amorphic to the holocrystalline. Few limestones are pure calcium carbonate. Impurities are easily mixed with the lime during the formation. Magnesium is often found in considerable quantities, when the variety is called magnesian. When this amount exceeds 45.65 per cent the stone takes the name of dolomite. Dolomite has a specific gravity of about 2.9.

Silica and clay are often found in composition, and when they exist in quantities exceeding 10 per cent the stone is said to be hydraulic. That is, upon being burned and ground it can be made. into mortar that will harden under water, a property not belonging to ordinary limestones. A specimen of this variety from Rondout, N. Y., analyzed according to Dana:

Marble is a name given to certain crystalline limestones that are of such a character as to be capable of receiving a high polish and so become of value for building purposes. Certain dolomites are also called marble.

Bedford Oolitic Limestone.

This stone is properly a calcareous sandstone or freestone, differing from sandstone in having its grains composed of carbonate of lime instead of quartz, and in the grains being small fossils instead of sediment transported by water from some former rockmass. It differs from other limestone in its granular texture and freestone grain.

It occurs in a bed varying from 25 to 100 feet in thickness. The greater portion of it is free from laminations or bedding seams. In almost every quarry or natural exposure there is at least one system of vertical joints, but they are rarely so numerous as to prevent the occurrence of the stone in large dimensions.

It is a granular stone, and both the grains and uniting cement are carbonate of lime. In the common sandstones the grains are hard and approximately angular; in this stone the grains are always soft and either round or rounded. In the silicious sandstones. the grains are harder than the cement, in the Bedford the cement is harder than the grains. These grains are nearly all small fossil forms, but when they are large, that portion of the stone containing them is thrown away and not used, the finest-grained being much

the better if it is uniform in texture and color. The original color was blue, but it is sometimes found buff and even a mixed blue and buff, according to the chemical changes in the iron compound.

It is found in several counties of Indiana and extends across the Ohio River into the State of Kentucky. It takes its name from the village of Bedford, Indiana.

A series of tests to determine its compressive strength gave an average of 7000 pounds per square inch with a maximum of 13,200 pounds.

Experiments on 1-inch cubes were also made to ascertain its fire-resisting qualities. Heated to 1000° F. and plunged into cold water the samples were not affected. Heated to 1200° and treated in the same manner the cubes crumbled slightly along the lower edges. Heated to 1500° and cooled in the air the cubes retained their form, but were calcined in a marked degree.

The principal use of this stone is for building purposes. It is easily cut when taken from the quarry, but hardens upon exposure to the atmosphere. It is also used in street construction for curbing and flagging, being easily sawed to any required dimensions.

This deposit takes its name from a township in Oneida County, New York. It is one of the most important in this country, extending from Maine on the east to the Rocky Mountains on the west and from Hudson's Bay to Alabama. By its decay it has formed soils of great fertility. That of the celebrated Blue Grass region of Kentucky is a direct product of the decomposition of this stone.

Total.

In its original locality it is dark blue in color, verging to black and lying in even beds which are sometimes separated by layers of black shale. It contains well-preserved specimens of the Lower Silurian Age. It changes in color and composition as it extends in different directions, but is easily followed by its distinctive features.

It is used for building purposes, burned into lime, and broken up for road-building, according to the wants of any particular section where it is located.

Table No. 5 gives the result of several analyses of this stone.

Table No. 6 shows the analyses of different limestones and their resulting limes.

Stone. Lime. Stone. Lime. Stone. Lime. Stone. Lime.