Alkali vegetabile nitratum (common nitre) forms upon the ſurface of the earth where vegetables, eſpecially when mixed with animal ſubſtances, putrify. The alkaline baſis previously exiſts in the plants[[19]], but the origin of the acid is not ſo well underſtood: whether it lies concealed in the vegetable acid, and by means of the putrefactive proceſs ſufficiently dephlogiſticating it, is evolved; or whether the purer part of the atmoſpheric air contains nitrous acid fully ſaturated with phlogiſton, which[[20]] upon the alkaly being ſeparated by the putrefaction is attracted and extricated by it, and upon loſing its inflammable principle aſſumes its accuſtomed form. Nature perhaps operates in both ways; the latter however ſeems clearly confirmed by a very remarkable experiment (§ 60.)
As nitre is annually produced in large quantities, it cannot but ſometimes be found in ſprings or wells, as has been obſerved at Berlin[[21]], London[[22]], and elſewhere[[23]]. Sometimes it abounds in ſuch quantities that fleſh boiled in theſe waters turns red.
ALKALI vegetabile ſalitum (digeſtive ſalt) is ſometimes though rarely met with; generated perhaps by the deſtruction of animal and vegetable ſubſtances.
ALKALI minerale vitriolatum (Glauber’s ſalt) is ſometimes found in waters. Some of the lakes in Siberia and Astracan contain it, and many ſprings in other places.
ALKALI minerale nitratum (cubic nitre) rarely occurs but where maritime plants putrify.
ALKALI minerale ſalitum (common ſalt) plentiful every where as well in the earth, where it forms ſtrata more or leſs thick (ſal gem), as alſo diſſolved in ſprings and lakes, and in the ſea. (ſea ſalt.)