This opinion is valuable because it has been stoutly asserted, that however well guano might answer at the South, it was of no use in the hard soil and cold climate of New England. This is a fallacy which will soon be cured by knowledge, and self-interest is a very strong prompter towards the acquisition of the knowledge, that guano is the best, cheapest, most suitable, convenient and productive manure ever used by a New England farmer, and just as suitable for that climate and soil as it is for Virginia. We assert, without fear of successful contradiction, that there is not a farm—not a field—covered with five-finger vines and mullens, in the State of Massachusetts, which may not be made to produce as profitable crops, by the use of guano, as any Connecticut river farm. Farmers are about the hardest class of men in the world to learn new doctrines; or that science has anything to do with the business of this life, and what all other life in a civilized country is dependent upon. Yet science teaches, by unerring truths, that the plants the farmer cultivates, are composed of carbon, obtained by plants chiefly from the soil and atmosphere; oxygen and hydrogen, obtained by plants chiefly from water, carbonic acid, &c.; nitrogen obtained by plants chiefly from manure, and also from rain and snow; silicium, in combination with oxygen, called silicia or sand; lime in combination with phosphoric and other acids; potash and soda in combination with acids; magnesia, in combination with acids, and various oxides of metals, the presence of which, however, is not very important, as they exist in an exceedingly small quantity. And that guano is composed of ammonia (formed of nitrogen and hydrogen,) combined with carbonic, oxalic, phosphoric, and other acids; lime, combined with phosphoric oxalic, and other acids; potash and soda, combined with muriatic and sulphuric acids; magnesia, combined with phosphoric and other acids; animal organic matter, containing carbon, and also nitrogen.

Now, is it not enough to prove that all the ingredients, with the exception of the metallic oxides, exist in guano, which are required by the plants grown for the sustenance of man.

Putting guano into the soil, therefore, as a manure, is clearly restoring to the earth those substances which plants abstract from it, and which are absolutely necessary for their growth.

The questions, then, which the farmer should now ask are, "which is best for me to buy, guano or coarse manure?" The evidence just given answers that question. "I have manure, teams, and men to haul it; my fields are from one to three miles distant, is it economy for me to let my teams lay idle and buy guano?" By no means. But you can probably employ men and teams in other improvements to much better advantage. With your manure make all your home lots exceedingly rich. With your men and teams clear off stones, dig ditches to put them into, drain your land, or build fence—bring bog meadows and swamps into dry cultivation—send every little brook through artificial channels for irrigation—send water up from lowland springs and streams by hydraulic rams for the same purpose, and for stock on the hills; or bring it down from hillsides if you are so situated; and buy guano for those distant fields, instead of wasting time in the laborious operation of hauling manure. Those who use guano, are enabled by the saving of time, to say nothing of their increased profits, to make improvements which are utterly impossible to accomplish under the old system.

How to choose Guano.—As we are satisfied no sensible reader can have perused the preceding pages, without having come to the determination to make a trial for himself, we will give him some general instructions about buying guano.

In the first place, we lay it down as an incontrovertible axiom, that the Peruvian guano, at the current price for years of that and all other, is the cheapest and best, because it contains the largest amount of ammonia, in a perfectly dry state; as a carbonate, true, but because dry, it is permanent and not likely to loose by volatilization by long keeping.

If other varieties contain a larger proportion of phosphates, and are sold at a less price, experience proves they are not cheaper. If an additional quantity of phosphates is desirable, it can be obtained in a cheaper form from dissolved bones, or bone dust and shavings of bone workers; or from mineral phosphates of lime. Recollect, guano under no other name, has ever equalled the Peruvian, in the results as compared with the quality or cost.

Therefore buy none but Peruvian. To guard against deception, be careful of whom you buy. If you cannot buy directly from the agents, be sure the character of your merchant is a sufficient guarantee against adulteration.

To test the quality of Guano.—The best test is the price. Unlike other merchandise, this article is not subject to fluctuations. Being a government monopoly, the price at which the agents are to sell here is fixed in Peru, and that price may be easily known; therefore, if any dealer offers you Peruvian guano at "a reduced price," you may be sure the quality is reduced also. Remember, that the lowest price by the ship load, it can be procured for of the agents in Baltimore or New York is $46 per ton of 2240 lbs. To this, every fair, honest dealer, must add freight, insurance and profit. Every man who sells without such addition, you may be sure will make his profit by short weight or adulteration.

The next best test is its appearance. Good Peruvian guano is an impalpable powder, perfectly dry to the touch, of a uniform brownish yellow color, with a strong smell, like that of spirits of hartshorn, contained in ammoniacal smelling bottles. But the smell is no test; that which smells strongest may be worst, as the ammonia may be disengaged by moisture or by the addition of lime or salt.