Limestone In The Valley of VA

MESSRS. GALLAHER:– The following facts with regard to the limestone of this section of the Valley o’ Virginia, deduced from Professor Wm. B. Rogers’ Report of the progress of the Geological Survey of the State of Virginia for the year 1838, made to the General Assembly during the last session, (1839,) are most of them of so much practical value, and all of them of so much importance, in my opinion, as to entitle them to a place in your paper, which the interest you have always manifested in matters of both practical and speculative science, will no doubt readily concede to them.

FACT 1. That there are two varieties of the limestone found in this region of the Valley as well as throughout the whole Valley, which are peculiarly rich in lime; namely, “The dark blue limestone of fine grain and smooth fracture,” which yields on burning “a beautifully white lime.”

“The dun coloured limestone, very close grain and rounded fracture,” which on being burnt yields a lime “equally fair and rather purer” than the dark blue limestone.

2. The lime from these varieties are well “suited for the purpose of ordinary mortar,” but will not set under water, (will not form the Hydraulic cement.)

3. That the lime best calculated to set under water, or in other words to form the Hydraulic cement, is that lime which is contained in rocks containing “a large proportion of carbonate of magnesia along with the cabonate of lime.”

4. That limestones, containing this magnesia, and consequently “capable, when burnt, of forming the Hydraulic cement,” are abundant in this section of the Valley.

5. That the limestone, containing this large proportion of magnesia, and of course useful in forming lime for the Hydraulic cement, may be known and distinguished from other varieties of limestone, by these appearances, viz: “Blueish grey tint, frequently blended with a tinge of yellow or brown, dullness of surface, when freshly broken, absence the smooth grain of the pure varieties of limestone, and a tendency to the slaty structure,” and also by the action of “diluted Sulphuric acid on the stone reduced to powder,” the result being, if magnesia be present, crystals of Sulphat of Magnesia or Epsom Salts.

6. That the same Magnesian Limestone, which has yielded such immense quantities of valuable cement on the Potomac near Shepherdstown, extends in a “Southward” direction, from that place, and “passes very near the village of Charlestown and Millwood.”

7. That an examination of a specimen of limestone “from Evett’s Ru, 34 miles from Charlestown,” showed it to contain the same ingredients necessary for the setting under water or formation of Hydraulic cement, which the limestone at Reynold’s quarry near Shepherdstown contains.

8. The interence is plain that quarries might be opened in other parts of Jefferson county yielding the Hydraulic lime equally with those near Shepherdstown.

9. That from the experience of observation of Prof. ROGERS, the application of lime to soil leads to the most beneficial results, and that the lime, made of stone containing a large amount of magnesia in its composition, (which is the character of a great deal of our Valley limestone,) is most beneficial to soil.