4. _The manner of lixiviating saltpetre earths._ The lixiviation is an important part of the process, however simple it may appear; as upon its accuracy depends the quantity of the product. 5. _The treatment of the different waters (lixiviums) with potash, sulphate of potassa, and wood-ashes._ This article points out the use of potash in decomposing the earthy salts, such as nitrate of lime; of sulphate of potassa, which converts the nitrate of lime by double decomposition into nitrate of potassa, the sulphate of lime being precipitated; and of wood-ashes, which act in the same manner as potash, as they contain this alkali. 6. _The evaporation of saltpetre waters, and the crystallization of nitre._ In this article, they consider the separation of foreign alkaline salts, as muriate of soda, and the crystallization of the nitre, to obtain it in a state of purity. 7. _The treatment of the mother water of crystallization._ This article refers to the manner of using the mother water, in order to obtain more nitre from it, and its employment in lieu of fresh water for other lixiviums. 8. _The refining of saltpetre by the old process._ They describe here the old process, in which a variety of substances were used to purify the saltpetre, but which is now generally abandoned, or laid aside. 9. _The process of refining saltpetre, as adopted in the establishments of the administration._ Under this head they give, in detail, the process employed throughout France, as uniform and the same, in every refinery. 10. _The manner of proceeding in the examination of various kinds of saltpetre in the magazines of the administration._ This article relates to the different modes of examining saltpetre. 11. _On the manufacture of potash and pearlash._ This subject is important, as potash is an indispensable article in the preparation of saltpetre, and the formation of the alkali may be considered as of primary magnitude in establishments, conducted upon so large a scale as those of France. It is thus, that a regular system is adopted, by the French government, for the production of saltpetre; and we may add also, for the manufacture of gunpowder, which we notice in that article. It may be proper to mention some facts, respecting the formation of nitre-beds, and the means adopted, in this way, to obtain saltpetre, and to offer, at the same time, some observations on this mode of obtaining nitre.