Fossil, or mineral, alkali abounds chiefly in Egypt, Tripoli in Barbary, Hungary, several RussianProvinces, and some parts of Asia; but it has seldom been found in the western countries of Europe, except in the vicinity of volcanoes, or in mineral waters ; and in these it exists only in very small portions.
The chief source of this alkali is the-water of the ocean. It forms the basis of sea-salt; and, as it is art article of the greatest utility, different methods of extracting it have lately been invented.
In August, 1781, a patent was granted to Mr. Alex. Fordyce, for his new processes, by which the alkali contained in sea-salt, rock-salt, salt-springs, salt-cake, Glau-ber's-salt, and vitriolated tartar, may be separated from the marine or vitriolic acids. - He first converts salt-water, etc. into Glauber's salt, by the application of vitriolic acid, or of any substance containing the latter. This salt is then to be mixed with a double quantity of lime, chalk, or any other calcareous earth, or iron, or with any substance containing that metal. The whole is to be placed together in a vault, or other reservoir, secured from the rain, till it is completely decomposed, when the alkali is to be ex-tracted by dissolving it in water, and evaporating it to dryness. Or, the patentee employs 60lbs. of Glauber's salt, or vitriolated tartar; l0lbs. of charcoal, or any other sub-stance capable of bearing heat, and containing the inflammable prin-ciple; and l0lbs. of iron : these ingredients are pounded together, and thrown into forty gallons of water; where they are suffered to digest for twenty-four hours. The clear solution is then to be separated ; and, by evaporating, filtering, and crystallizing, it is rendered fit for use.
Another patent was granted in March 1789, to Mr. Anthony Bourboulon de Boneuil, of Liverpool, for his invention of an apparatus on a new construction, and certain new processes for the making of fossil alkali, which is said to be equal to that extracted from the best barilla. - As, how ever, his specification is so com-plex, that it could not be understood without the aid of an engraving ; and, as the patent is not expired, we refer the reader to the 4th vol. of the "Repertory of Arts and Manufactures
The last process which merits our attention, is that of the Earl of Dundonald, for obtaining mineral or fossil, and vegetable alkali, from neutral salts composed of those alkalies and an acid ; or from the solutions of those salts, whence several articles are disengaged or formed, that may be collected and applied to various useful purposes. For these different inventions, his Lordship obtained a patent in 1795.
1. The most important of the new processes, is that of making Glauber's salt, or sulphat of soda, which is one of those neutral salts, consisting of an alkali and an acid, from which an alkaline salt is to be procured. Thus, several other articles, such as spirit of salt, sal ammoniac, and an iron earth mixed with clay, as a pigment, are formed, or disengaged, and may be collected: 2. Glauber's salt is decomposed, forming mineral alkali, or soda, either in a mild or caustic state : 3. Vitriolated tartar is prepared by decomposing the muriat of pot-ash ; and 4. This preparation is converted into either a vegetable alkaline hepar, or mild or caustic vegetable alkali. The salts and other substances resulting from these chemical operations, may be applied to various purposes, particularly for decomposing 6oda from Glauber's salt.
As the principal article for which Lord Dundonald has established manufactories, appears to be the Soda now generally sold in the shops, we shall, in the alphabetical series, describe its manifold uses, and content ourselves at present with giving a summary of the inventions claimed by the noble patentee : namely, that sea-salt is decomposed by alum, by vitriol of iron, and Epsom-salt, with the acid of heat, when a due proportion of clay, or a clayey iron earth is mixed with the salts submitted to the operation ; - that sea-salt is also decomposed by Epsom-salt with the aid of heat, and without the intervention of clay ; - lastly, that it may likewise be reduced by sulphat of lime, or gypsum, with the aid of heat, when a due proportion of clay, containing much iron, is mixed with the sea-salt and gypsum.