Of these sodium stannate, Na2Sn03, is produced industrially by heating tin with Chile saltpetre and caustic soda, or by fusing very finely powdered tinstone with caustic soda in iron vessels.
The Rotunda, where are the ruins of the old saltpetre works; the Star Chamber, where the protrusion of white crystals through a coating of the black oxide of manganese creates an optical illusion of great beauty; the Chief City, where an area of 2 acres is covered by a vault 125 ft.
The chief applications of Chile saltpetre are in the nitric acid industry, and in the manufacture of ordinary saltpetre for making gunpowder, ordinary Chile saltpetre being unsuitable by reason of its deliquescent nature, a property, however, not exhibited by the perfectly pure salt.
Chile saltpetre, cubic nitre or sodium nitrate, NaNO,, occurs under the same conditions as ordinary saltpetre in deposits covering immense areas in South America, which are known locally as caliche or terra salitrosa, and abound especially in the provinces of Tarapaca and Antofagasta in Chile.
The more important picric powders are melinite, believed to be a mixture of fused picric acid and gun-cotton; lyddite, the British service explosive, and shimose, the Japanese powder, both supposed to be identical with the original melinite; Brugere's powder, a mixture of 54 parts of ammonium picrate and 45 parts of saltpetre; Designolle's powder, composed of potassium picrate, saltpetre and charcoal; and emmensite, invented by Stephen Emmens, of the United States.
The political convulsions of Italy in 1799 brought Breislak to Paris, where he remained until 1802, when, being appointed inspector of the saltpetre and powder manufactories near Milan, he removed to that city.
Ordinary Saltpetre or Potassium Nitrate, KN03, occurs, mingled with other nitrates, on the surface and in the superficial layers of the soil in many countries, especially in certain parts of India, Persia, Arabia and Spain.
For the nitrite, see Nitrogen, for the nitrate see Saltpetre and for the cyanide see Prussic Acid; for other salts see the articles wherein the corresponding acid receives treatment.
The chief exports are rice, indigo, linseed and other seeds, saltpetre and tobacco.
Sulphuric acid may be applied as such on the ores placed in lead, brick, or stone chambers; or as a mixture of sulphur dioxide, nitrous fumes (generated from Chile saltpetre and sulphuric acid), and steam, which permeates the ore resting on the false bottom of a brick chamber.