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iron rollers about eighteen inches in diameter. The first rollers are placed above the second pair, which are set close together, reducing the stones to about the size of peas. They are then passed through millstones similar to those used to grind wheat, but driven with greater speed. The powder is then placed in a large iron vessel lined with lead, having within it a number of paddles revolving with great rapidity; water sufficient is added to convert it into a thick cream; sulphuric acid is now added, and the mixture agitated with the paddles, similarly to the process of churning, for about five minutes. The semi-fluid mass is then thrown out and placed in a heap; and such is the heat generated by the process, that in a few days it will become solid, and may be placed in bags. In this factory fifteen hundred tons are usually placed in a heap, which will remain hot for months; the heat materially aiding the decomposition of the phosphates. Bones alone do not make a solid manure when mixed with sulphuric acid; but if a portion of the mineral phosphate of lime is used with them, they form a very valuable and efficacious manure, which can be transported in bags and sown without admixture with ashes.

As before stated, the Spanish phosphate of lime (apatite) is too expensive to use for agricultural purposes. Yet Mr. Lawes obtained a quan. tity and made a few experiments with it; which, as this substance closely resembles the American phosphate of lime, it may be interesting to give:

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TURNIP EXPERIMENTS.

Description of manure used per acre.

Turnip bulbs.

Tons. Cwt.

2 No manure....

45

3 Three cwt. finely-ground apatite..

1 Two hundred pounds apatite, decomposed with sulphuric acid.. 6 15% Five cwt. super-phosphate of lime manufactured from calcined bones..

... 7 141

It is seen that three hundred and thirty-six pounds of undecomposed apatite, though reduced to the finest powder, gave an increase of only sixteen and three quarters cwt. of turnip bulbs per acre; while two hundred pounds manufactured into super.phosphate of lime gave an increase over the unmanured acre of four tons and eleven and a half cwt., and more than double that of the undecomposed apatite. The acre dressed with super-phosphate of lime from calcined bones gives a slight increase over the decomposed apatite, but not in a corresponding ratio with the increased quantity applied,

From this we may conclude that mineral phosphate of lime, provided it contain the same amount of phosphcric acid and no deleterious substances, is just as good as that obtained from bones when both are made into super-phosphate of lime. If both are applied in their undecomposed state, the calcined bones appear to be slightly soluble, and to have a better effect than the ground apatite. The value of phosphate of lime in England in such substances as apatite, coprolites, &c., is twenty-four cents per ton for every one cent of bone earth phosphate which they contain. Thus, if a substance contains eighty per cent. phosphate of

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lime, it will be worth $19 20 per ton; if ninety, it will be worth $21 60 per ton in any British port in its natural state. If, however, it contains but a small per centage of phosphate of lime, and considerable carbonate or fluoride of lime, its value, calculated on the per.centage of phosphate of lime, will be considerably reduced, inasmuch as the substances have to be neutralized before the sulphuric acid will act upon the lime. The price of boiled bones is $21 per ton; or, calculating them to contain sixty per cent. of phosphate of lime, $7 per ton higher than they would be worth according to the above method of valuation; but it must be remembered they contain some organic matter which, especially the nitrogen, is very valuable. The wholesale price of super.phosphate of lime in London, manufactured from the Suffolk coprolites which have been described, is $20 pör ton; that manufactured from calcined bones, Saldanha Bay giann, &c., is worth $33 per ton.

We must now consider, as being more interesting to our farmers, the value of the recent discovery of unlimited, almost pure, phosphate of lime in the United States, especially that of Crown Point, Essex county, New York, and that of the New Jersey Zinc Company. The former, we believe, was discovered by Professor Emmons, of Albany, and is sup. posed to be the richest vein of phosphate of lime in the world. Some selected specimens have been found to contain ninety per cent. of boneearth phosphate. Several barrels have been sent to England for trial, where, provided it can be furnished cheap enough, it will be largely used. The samples sent there do not appear to have been well selected, and contained considerable quartz; which, as the facilities for working the mine increase, will be avoided. A large lump of it was broken up, and a fair specimen taken for analysis by Professor Way, with the following result:

Composition of the American Phosphate of Lime.
Bituminous matter and water expelled at red-heat....
Substances insoluble in acid, chiefly quartz sand..
Silica (soluble in acids)...
Phosphoric acid, equal to 62. 27 bone earth phosphate.
Lime
Peroxide of iron..
Magnesia .....
Chloride of sodium.
Soda....
Potash..
Sulphuric acid....
Fluorine and loss in analysis.

0.69 16.79

9.65 30. 20 40.10 6.47 1.03 0.08 0.20 0.25 trace. 3.49

100.00

This is a much superior article to the Suffolk coprolites, though I believe the above is not so good as the average of that obtained from the same source. It is not so hard, and requires but little labor to pulverize it; and hence it will be manufactured into super phosphate of lime at a much less cost of labor and machinery than the coprolites now used in England. The absence, too, of carbonate of lime, of which twenty-five

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per cent. is found in the coprolites, is a very great advantage, requiring a much less quantity of sulphuric acid for its manufacture into superphosphate of lime.

It would be useless to give the amount of sulphuric acid needed for the conversion of this article into super-phosphate of lime, deduced from the above analysis; for, though there can be no doubt that the figures represent the true composition of the sample analyzed, yet they considerably underrate the amount of phosphate of lime which a well selected quantity would contain; and it will be easy for any one to calculate the quantity of acid best to use the amount of phosphate of lime and lime being known) from the date before given. But it must be borne in mind that, when speaking of sulphuric acid, I have referred to the pure anhydrous acid, and not to oil of vitriol, or the commercial sul. phuric or brown acid. At the end of this paper will be found a table of Dr. Acre's, showing the amount of real sulphuric acid contained in oil of vitriol of various densities. The “chamber,” or “ brown acid," of the manufactures of Sp. Gr. 1.7 is the cheapest and most generally used article for the manfacture of super-phosphate of lime; one hundred pounds of this acid contain sixty-five pounds of real sulphuric acid; its wholesale price in London is eleven mills per pound; there being but little demand for this article at present; the price is much higher; but as the demand increases it will doubtless be manufactured on a large scale, at a much less cost; it is now sold by the car boy, in the principal cities, at 2} to 3 cents per pound; it is not so dangerous to use as most people imagine, and, if ordinary care is exercised, nothing need happen worse than an occasional blotch of the clothes and a stain on the boots, &c.

It is not probable that the mineral phosphate will be manufactured by the farmers themselves; so that I need not dwell on it any lor:ger. But bones are of great importance, and at the command, to some extent, of every farmer, who would find it much to his interest to convert them into manure for his soil, rather than let them lie bleaching in the sun in some out-of-the-way place, shedding their odor on the desert air. Bones, if finely ground, will do good if applied in their natural state; but their benefit is small and slow; and it is best to decompose them with sulphuric acid, especially as a manure for turnips, rutabagas, young trees, cabbage, beets, &c. To use acid economically the bones should always be finely ground; one hundred pounds of fresh bones contain

Phosphate of lime..
Carbonate of lime.

4.5 4.0

Now, to convert these forty-five pounds phosphate into bi-phosphate of lime, it will be found from data previously given (page 308) that we have got to abstract 14 pounds of lime by sulphuric acid, converting it into sulphate of lime. "To do this, twenty pounds of real sulphuric acid would be required, or 31 pounds of brown or chamber acid, (Sp. Gr. 1.7;) but before the acid will act on the phosphate the carbonate of lime must be converted into a sulphate; to do this 34 pounds real acid will be neutralized, or five pounds of the brown acid, (Sp. Gr. 1.7.) We have, therefore, in the manufacture of super-phosphate of lime from bones, to put about twenty-four pounds of real sulphuric acid, or thirtyseven pounds of brown acid, (Sp. Gr. 1.7,) to one hundred pounds of the bone dust.

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A good method for the farmer to make his own super-phosphate of lime, is to get a large tub, or end of a cask, place in it ihe quantity of bone dust that can be best worked at a time-say 60 pounds; sufficient water should then be added just to wet all the bones; let this be stirred till the dust is all wet, and then add the proper quantity of acid, 22 pounds, (Sp. Gr. 1.7.) When mixed, it can be thrown into a heap on the floor, and the process repeated. The operation should be done expeditiously, and the larger the heap the better, as the heat engendered during the process materially assists the acid in decomposing the phosphate.

Some farmers think the above method too tedious, and prefer placing the whole amount of dust in a large heap on a wooden floor; wet it with water and apply the acid in small quantities, repeatedly turning the heap and applying the acid till the proper quantity is used. This plan does not require so much labor, but the farmer insures a more equally mixed and better manufactured article. When properly manufactured it will be sufficiently dry to sow by hand without any absorbent substance, but if drilled, as it always should be when used as a manure for turnips, it is necessary to mix with it some dry materials—such as coal ashes, dry, leached ashes, saw.dust, peat, &c.; but on no consideration let lime, wood-ashes, or any other caustic alkalies or alkaline earth be used, for a reaction immediately takes place, and the bi.phosphate is converted back again into the bone earth phosphate of lime, and all the labor has been in vain.

Super.phosphate of lime, manufactured from fresh bones, is doubtless much the best article, if employed as a manure for wheat, corn, Timothy, . &c., as, besides the phosphoric acid, it contains considerable nitrogen. Fresh bones contain 5 per cent. of nitrogen, which, at the present value

5 of ammonia, in guano or sulphate of ammonia, would make bones worth, for this element alone, 50 cents per 100 pounds; and, according to the estimate of Mr. Lawes-that 5 pounds of ammonia will produce an extra bushel of wheat--we might expect a little more than a bushel by the application of 100 pounds of fresli bones. The super.phosphate manufactured from the apatite, or, as Professor Emmons named it, the eupyr. chroite, would be a purely mineral manure, and would have no beneficial effect on wheat, unless the soil was agriculturally deficient of phosphoric acid, and in that case it would only raise the produce to the natural or normal produce of the soil - say 15 to 20 bushels of grain.

In relation to the discovery of the mineral phosphate in this country, Professor Johnston has said, “ American farmers, in general, have not the knowledge to appreciate the value of such a manuring substance as this, nor the ability to purchase it, when manufactured into super-phosphate of lime; the discovery, therefore, will be a boon for the present to both countries. It will make more abundant and cheap the means of fertility, which our soils require, while, by supplying a new article of traffic, only salable in Great Britain, it will form a new bond of connexion between our kindred nations."

The English farmers are most loudly and justly complaining of high rents, high taxes, and low prices in consequence of free trade; and it is American competition that they must fear. They think that, with a good climate, admirable means of transportation, both natural and artificial, a rich, new soil, which can be had comparatively for nothing, the American farmers will inundate their market with cheap wheat, corn, beef,

pork, butter, and cheese, and thus ruin them. Now, Professor Johnston, with the feelings of a philanthropist, wished to cheer the half-brokenhearted farmer in this his hour of need; and to do it, he has, unfortunately for the poor farmers, deceived them. He has represented this country as scarcely able to raise wheat sufficient for its own population, and that, while this population is increasing at an extraordinary rapidity, the wheat soils are gradually losing their fertility, and that farmers in the rich Genesee country are laying their land down to grass, finding it unprofitable to grow wheat at present prices.

The motive of the Professor is at once apparent, and all intelligent British farmers readily perceive it. This laudable motive induced him to assert that the discovery of large quantities of rich phosphate of lime would be of no benefit but to the British agriculturist; that the American farmer had neither the knowledge to appreciate, nor the money to purchase, such an article, &c. A careful reader would be led to conclude that Professor Johnston was mistaken; for he himself says that he found the American farmers very intelligent, and generally well acquainted with the geological formation of their soils, and the influence it had on their adaptation to certain crops, and, also, that they were earnestly seeking all the information that was to be obtained from science; that his lectures were listened to with great attention, and that the State of New York had ordered several thousand copies to be printed for gratuitous distribution. Does this show an indifference to agricultural science? Undoubtedly not. If the learned Professor taught any system of agriculture that could be profitably adopted by American farmers, their love of money, if nothing else, would insure its universal and instantaneous adoption. “It will pay them to use super.phosphate of lime as a manure for American soils, if American farmers have intelligence enough to sow it.” If Professor Johnston really believed what he wrote, the American farmers, I venture to predict, will speedily undeceive him. It will be found that, while it is a valuable export, and a commodity which British soils require, it will soon be considered not only useful, but indispensable to American agriculture. Unfortunately for the British tenant farmer, overburdened, as he is, with rent, taxes, hedge-row timber, and game, which he must keep, but not eat, America will continue to keep down the English market at that price which the British farmer will find hard to sell at and pay a high rent.

If it will pay the British farmer to use the super-phosphate, why will it not pay the American? Hitherto the prices of grain and provisions have been much higher there than here; but now prices are nearly as high for wheat and meat in New as in Old England; while potatoes, and all kinds of roots, are double the price here that they are there. The answer to this inquiry brings us back to the former position, that root crops inust be extensively cultivated. That it will be profitable to do so, there is no doubt. I have myself had fears that this climate was not favorable to their growth, but facts do not sustain them; and it is now pretty well established that great crops of rutabaga, or, as they are called in England, the Swedish turnip, can be easily raised in this county: In fact, some of the crops to which agricultural societies have awarded premiums this last fall were, according to the published statements, much heavier than any crop I ever saw grown in the best British turnip districts, under the most favorable condition of soil and manuring. Let

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