672 GEOLOGY OF OHIO. 
referred to this division, though not more than twelve feet are ordi- 
narily worked. At Holcomb’s quarries, below Springfield, thirteen feet 
are shown in a full section of the series. 
The courses vary in thickness from four to fourteen inches. Those 
which are most valued for building stone generally range between these 
extremes. Several of the courses answer a fair purpose for cutting stone. 
The same qualified commendation can be given to them for flagging. 
In neither of these respects has there been, as yet, sufficient inducement 
to fully develop the capabilities of the beds. But for general masonry 
they leave little to be desired. Easily raised and dressed, of convenient 
thickness and of ample surface, they are not surpassed by any stone in 
the State in economy of use. 
In color they are either blue or drab. The blue courses frequently 
weather to drab on their exposed edges, but it is by no means certain 
that the drab beds have all been derived from the blue by this process of 
weathering. Slight differences in chemical constitution would serve to 
explain these differences in color. 
‘In what has been said of the value of these beds for building stone, it 
has been, of course, implied that they are durable. Durability cannot, 
however, be asserted of all the courses without exception. As in Clarke 
county, the blue beds sometimes prove treacherous, and this important 
question for each particular course can only be determined by a practical 
test. The firm and massive appearance of the stone when raised from — 
the quarry furnishes no safe guide in judging of its power to withstand 
atmospheric agencies. By far the largest portion of the stratum, how- 
ever, has great excellence in this respect. The drab courses are, almost 
without exception, entirely satisfactory. 
The composition of the Springfield stone has been incidentally alluded 
to. A sample of the blue rock taken from the quarries of W. Sroufe, Esq., 
of Yellow Springs, gave the following result. (Wormley.) 
CarbonateOP dime cei sess ccscesead-Teoteecem se uasteceisectoeceels averse cemem sere ament ant 51.10 
Warbonaterol Magnesia: wile ahr! NER ORUANA Sela a Maia 41.12 
Sandrarid siiea wes ee Ee eH OTT UTE aS NR ea araag 5.40 
Alumina, wathi trace sOf nom j.cclucccecas cscs. saceteneccect pteenes soe ecenedaecsicosees 1.40 
99.02 
A magnesian limestone of France, cited by Vicat as furnishing an ex- 
_ cellent hydraulic lime, was, by chance, noticed to have an almost identical 
composition. Hxperiments were instituted with reference to hydraulic 
properties in the stone now under consideration, and it was found to 
have great energy asacement. It can scarcely be doubted that these 
home supplies will come to be utilized at no distant day. Attention is 
