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In Eastern and Central Texas, there is a reddish brown sandrock, used by the International Railroad Company for the stone work of their road. It has also been largely used for chimneys, for this purpose being much better than brick. It is colored by the red oxide of iron, is fine grained and compact, forming more beautiful walls than the browd sandstones of Connecticut and New Jersey, which have been so largely used for building purposes in brew York and other cities. The Texas rock prevails in the iron region of the tertiary. Mountains of it are in Milam, Robertson, Cherokee and other counties.

In the bank of Honey creek, near Packsaddle Mountain, is a slate rock, which probably belongs to the laurentian period, it being older than the potsdam sandstone, which overlies it. It is very similar in appearance to slates or Vermont and New Hampshire, which are used for roofs. We only obtained outside specimens of it, and those are not of sufficient firmness for roofs. It is highly probable that the interior slates are more hard and compact. This rock prevails in the region around Packsaddle in strata, dipping at large angles, often being nearly perpendicular, it having been uplifted from its original position by the upheaval of the granite.

which forms a cement which will set or become firm under water. It is an impure limerocks composed of lime, clay sand and magnesia, to which is added, in the best cements, a little iron.

An analysis made by Beck, of an excellent kind, found at Rondont, N. Y., gave the following composition

There is little doubt but that many of our silicious and magnesian limestones will make good cements, to form which it is not necessary to have rocks composed of the exact proportions given in the above analysis.