Some limited portions of the earth, as the plains of Babylon, when under skilful cultivation, the valleys of the Indus and the Nile, and the fields of Sicily, almost since the days of the flood, have produced luxuriantly, without the aid of manure to any extent; but it must be remembered the former have their fertility annually renewed by the rich overflowings of the rivers, which are charged with all the materials necessary to restore exhausted nature; while the soil of the last, being wholly of basaltic origin, is rich in the alkalies, which a year or two of rest, is sufficient to replenish in a soluble state, to be again taken up by the luxuriant crop. Hence, we have witnessed a drainage of nearly all the products from these fertile regions, for thousands of years, with impunity. But they are exceptions which only go to prove the general rule. The farmer must look to it, that all the ingredients that enter into his crops, are supplied by the materials in his soil, or a deficiency, or entire failure, will be the inevitable result. Although all the constituents entering into the straw and grain, are absolutely essential to their perfection, they are not all equally essential to be contained in the soil. It is indispensable, however, that the earthy or inorganic portion of them be there, for these can not be obtained elsewhere. How shall they be best supplied? Ashes, it is believed, afford the cheapest, as well as one of the most effectual applications that can be made for grain. Of the ten fixed ingredients enumerated as entering into wheat, ashes yield potash, soda, lime, magnesia, sulphuric and phosphoric acids, in large proportions, and silica and iron in smaller. The chemical operation of the potash, and carbonate and sulphate of lime, however, when added to the soil, is to supply the silica, in a soluble state, from its natural condition, (it being found in abundance for this object in every soil, except in such as are formed almost exclusively of peat,) for the demands of the crop. An increased supply of lime and gypsum, beyond what is found in the ashes, is frequently advantageous; and when the latter is beneficial, as it generally is, it should never be withheld to an extent in the highest degree useful. Of the operation of this last material, beyond yielding a portion of its sulphur to the gluten, we have as yet no satisfactory explanation. In respect to the theory of its concentrating ammonia in the soil from the atmosphere, we have very contradictory authority. Liebig asserts it, Johnstone questions it, and Dana denies it; yet the increasing fertility its application produces, would seem to give the weight of experience in favor of Liebig's views.