14 MANGANESE AND POTASH. 



MANGANESE, OXIDE OF MANGANESE. 



It is not as yet determined that this oxide is an essential constituent of any class of plants. 

 So far as this question has been investigated, it appears to be an accidental substance in 

 the ash of plants. Like iron, it is soluble in organic acids, and forms an earthy black 

 substance, the particles of which cohere but slightly. It is analogous to bog ore, being 

 formed in the same way and in similar locations. The organic salt of manganese is un- 

 doubtedly the substance which is taken up by the roots of plants, and is occasionally 

 detected in small quantities by appropriate tests. 



POTASH. 



It is now well known that soils destitute of potash are nearly barren ; that, at least for 

 the cultivation of some plants, they are totally worthless. Liebig has proposed to divide 

 plants into groups or classes, according to the predominance of a particular earth or alkali. 

 This has some show of a systematic arrangement ; but when it is attempted to carry it out, 

 it fails, as generally in the composition of the seed we find potash ; in the leaves and stalks, 

 lime, etc. If the whole plant is taken into consideration, it is difficult to determine whether 

 it should be called a lime, potash, soda, magnesia or silica-plant. 



The original source of potash, and indeed of all the alkalies, is found in the rocks, par- 

 ticularly clay slate, and those containing felspar. In the Hoosic roofing slate 3 52 per 

 centum of potash exists; in a slate of the same age in Washington county, 0*60. Marls 

 and clays contain 0'50 to 1 and 2 per centum of potash and soda ; but one of the shales 

 from the Chemung series contains 5*47 per centum.* I have reason to believe, however, 

 that this large amount of potash is only local ; for it not unfrequently happens that a single 

 specimen yields a large amount of some, valuable fertilizer, as phosphate of lime ; but a 

 few yards distant, it is only in diminished quantities. 



For analyses of the rocks, clays, marls, limestones, etc., see Vol. I. of the Agriculture, 

 of New-York. Numerous analyses are also given in the American Journal quoted below. 



Potash, besides its direct use as a constituent itself of vegetables and animals, is equally 

 useful, if not more so, in rendering silica and other bodies soluble. Its absence, or its pre- 

 sence in insufficient quantities, is an evil which must be removed by a direct application of 

 those substances which contain it. Ashes of plants furnish it more economically than 

 other substances. Even leached ashes contain potash, and are competent to impart fertility 

 for many years ; and in this condition, too, they give tenacity to loose and sandy soils. 

 Our neighbors of Long Island understand well the value of leached ashes ; while the 

 farmers in the valley of the Mohawk have not yet discovered their use, and the fact that 

 they would do much to restore to fertility the worn out fields in this beautiful valley. 



* American Journal of Agriculture and Science, Dec. 1847, p. 343. 



