The manufacture of gunpowder.
--In connection with this subject the Montgomery correspondent of the Charleston Mercury makes the following interesting statement:

New discoveries of saltpetre have been made in Arkansas, which bid fair to furnish a quantity of that article to more than supply all our wants. It has been found in caves, in a crystalline form, and of fine quality. A large quantity has been found near Jacksonport, Jackson county, and in White county, within twenty and twenty-five miles of navigable waters. The mines in White county are now turning out from one to two thousand pounds of nitre daily, and a contract has just been completed with the chief of the Ordnance Bureau, to supply the Confederate States with one thousand pounds daily, to be delivered in Nashville, and an additional quantity, if wanted, landed at other points.--Sulphur has also been found in quantities.--From a late survey we learn that saltpetre, sulphur, lead, coal and iron, are found in abundance in the State of Arkansas. The saltpetre is found in caves and in positions where the mines can be easily worked, so that it will be but a short time before it can be gotten into market. Nitre, or saltpetre, is an important salt of potash that is found in great abundance throughout the world, wherever the mineral salts exists in any large quantities in the soil. The Mammoth Cave, Kentucky, has furnished large quantities of it, and it can be found in any cavern in this country, in all soils that contain materials undergoing decay. It is not found as mineral in the earth, nor is it manufactured except by the hand of Nature, wherever there is a heap of moist rubbish, with some base as potash or lime present. It is found in all lime soils especially, but if exposed to the rains it is washed out and consumed by vegetation. It is to be presumed that in limestone districts much nitre could be obtained by taking soil from under old negro houses, or heaps of decayed wood, and leaching it in hoppers, as is done in making lye, then boiling to dryness; but the recent discoveries in Arkansas will prevent resorting to such labor for sometime to come. Should necessity require, a few simple directions scattered among farmers might afford the Government an abundance of this material. As is well known, this important substance is used principally in the manufacture of gunpowder, into which it enters in the proportion of seventy-five parts in the hundred, although this proportion varies a little in different countries. I have been thus explicit in description of this matter, because it is now engaging considerable attention in scientific circles.

The Daily Dispatch (Richmond, VA) 25 May 1861