With assurances to my friends that I have no other interest in the increased consumption of guano, I am most sincerely and respectfully Your old Friend, SOLON ROBINSON. _New York, October 1852._ A TREATISE ON GUANO. PERUVIAN GUANO--ITS USES AND BENEFITS. Of all manures procurable by the American Farmer, guano from the rainless islands of Peru, is perhaps not only the most concentrated--the most economical to the purchaser--but by its composition, as we will show by analysis, the best adapted to all the crops cultivated in this country requiring manure. For wheat, especially, it is the one thing needful. The mineral constituents of cultivated plants, as will also be shown by analysis, are chiefly lime, magnesia, potash, soda, chlorine, sulphuric and phosphoric acid; all of which will be found in Peruvian guano. Nitrogen, the most valuable constituent of stable or compost manures, exists in great abundance in guano, in the exact condition required by plants to promote rapid vegetation. The concentration of all these valuable properties in the small bulk of guano, renders it particularly valuable to farms situated in districts unprovided with facilities of cheap transportation. In some hilly regions, it would be utterly impossible to make any ordinary manure pay for transportation. With guano the case is very different--one wagon will carry enough with a single pair of horses to dress 12 or 16 acres; while of stable manure it would require as many or more loads to each acre to produce the same effect. But this is not the greatest advantage in the use of this fertilizer; the first application puts the land in such condition, that judicious after cultivation renders it continuously fertile by its own action of productiveness and reproductiveness of wheat, clover and wheat, by turning in the clover of one year for the wheat of the next, and by returning the straw back to the ground where it grew, spread open the surface to shade the plants of clover and manure its roots, which in turn manure the corn or wheat. As a source of profit alone, we should recommend the continuous application of Guano; knowing as we do, from our extensive means of observation, that no outlay of capital ever made by the farmer, is so sure and certain to bring him back good returns for his money, as when he invests it in this invaluable fertilizer for his impoverished soil. In proof of this, we shall give the reader of this little work a number of experiments made by some of the most improving farmers in Virginia and other States. EFFECTS PRODUCED BY THE USE OF GUANO IN VIRGINIA.