Part I. Report of progress in 1869, by J. S. Newberry, chief geologist. Part II. Report of progress in the second district, by E. B. Andrews, assist. geologist. Part III. Report on geology of Montgomery County, by Edward Orton, assist. geologist.

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The properties of these limes are very different. Those of the first
class require to be submitted to a higher temperature in " burning " than
the second. They slake promptly and thoroughly, and in the operation
evolve a great degree of heat. From this last fact, they are termed
"hot" or " fiery" limes. They" set" or harden so soon that but two or
three bricks can be laid with one spreading of mortar, and walls that are
made of them have a tendency to "chip crack." It is quite likely that
this last named property can be attributed, in some degree, to the silica
and alumina which they contain.
The second group contains those limes that are called "cool." They
do not give out as much heat in slaking as the limes of the first class,
nor do they "set" as soon. From 5 to 20 bricks can be laid with a single
spreading of mortar, and in plastering a corresponding advantage can be
obtained.
On purely practical grounds, the builders of southwestern Ohio have
come to recognize the greater desirability of the limes of the last-named
class, and none others can now find a market in the cities and towns of
this portion of the State.
To the first series belong the Blue Limestones, the Clinton Group, and
the Dayton beds of the Niagara Group.
The limes of the second series are all obtained from the upper, or
Niagara, division of the Cliff limestones, and the kind of rocks from
which they are derived constitute almost the entire mass of this formation.
It thus appears that the Niagara Group in Ohio is a true magnesian limestone, as all the members of this same great series through its wide
western expansion-in Michigan, Wisconsin, Illinois, Iowa and Minnesota-have uniformly been found to be. The only exception to these statements as to the composition of the Niagara series, is found in some of its
lowermost beds, where, in limited and isolated areas, the Dayton stone
and its equivalents occur. This stone has already been referred to the
true limestones, an analysis of it, made by Dr. Locke in 1835, showing
that it contains 92 per cent. of carbonate of lime.
While with this exception the whole Niagara series consists of magnesian limestones, it would be wrong to conclude that every portion of this
series, taken indifferently, can be burned into valuable lime. The quarries that are worked -for lime burning at Cedarville, Yellow Springs,
Springfield, Moore's quarries below Springfield, Wilson's quarries north
of Dayton, and a few others less widely known, furnish the most valuable limes of the Miami valleys, and largely supply the markets of
Cincinnati, Dayton, Hamilton, Springfield, Xenia and the remaining
towns and villages of this section. These quarries all lie in the same
geological horizon, viz: between 50 and 100 feet above the base of the
Niagara rocks. They begin in or above the strata that contain the large
shell Pentamerus oblongus, and generally include from 10 to 20 feet that