There is a mineral phosphate of lime, Apatite, which has been known to exist in Estremadura, in Spain, for a long period. Dr. Daubeny and Capt. Willington, visited the locality a few years since for the purpose of ascertaining whether it existed in sufficient quantities for agricultural purposes. They describe it as a vein many feet thick extending over miles of country, but situated in a locality where it will have to be transported for a long distance upon the backs of mules. Some tons of this apatite were imported into England, but the price was necessarily much too high for commercial purposes. It is a hard chrystalized rock of a yellowish white, or greenish color, and composed according to Dr. Daubeny, of Professor Way in a small portion of this mineral found 851 per cent. of phosphate of lime. It resembles in many respects the phosphate of lime found at Crown Point, of which we shall speak further on. It contains no carbonate of lime, but the fourteen per cent. of fluoride of calcium is a great objection, as by it the effective strength of the sulphuric acid is considerably reduced; 100 lbs. fluoride of lime requiring 103 lbs. real sulphuric acid to convert it into sulphate of lime. The escape too of the fluorine gas in such large quantities is very obnoxious, and renders the manufacture of apatite into superphosphate of lime not only disagreeable but difficult. The process of manufacturing superphosphate of lime in the principal factory in England, is as follows: The stones (for such the coprolites are to all appearance,) are first reduced to a powder about the fineness of corn meal. This is accomplished by passing them through two cast 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 mill stones 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 1,500 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 quantity and made a few experiments with it; which as this substance closely resembles the American phosphate of lime, it may be interesting to give. 200 lbs. apatite, decomposed with sulphuric acid,.. 6 152 270 lbs. apatite and 104 lbs. sulphuric acid,.. 7 31 Five cwt. superphosphate of lime manufactured from cal cined bones, 7 143 It is seen that 336 lbs. of undecomposed apatite, though reduced to the finest powder, gave an increase of only 163 cwt. of turnip bulbs per acre, while 200 lbs. manufactured into superphosphate of lime gave an increase over the unmanured acre of 4 tons 11 cwt, and more than double that of the undecomposed apatite. The acre dressed with superphosphate 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, providing it contain the same amount of phosphoric acid and no deleterious substances, is just as good as that obtained from bones, when both are made into superphosphate 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 24 cents per ton, for every one per cent of bone earth phosphate which they contain; thus, if a substance contains 80 per cent phosphate of lime, it will be worth $19.20 per ton, if 90, 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 phospate 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 60 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 superphosphate of lime in London, manufactured from the Suffolk coprolites, which have been described, is $20 per ton. That manufactured from calcined bones, Saldana bay guano, &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 co., N. Y., and that of the New-Jersey Zine Company. The former, we believe, was discovered by Professor Emmons, of Albany, and is supposed to be the richest vein of phosphate of lime in the world. Some selected specimens have been found to contain 90 per cent. of bone earth 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 Prof. Way, with the following result: Composition of the American Phosphate of Lime. .... Phosphoric acid, equal to 62.27 bone earth phosphate, 0.69 16.79 9.65 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 superphosphate 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 25 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 superphosphate of lime, deduced from the above analysis, for though there can be no doubt that the figures represent the true composition of the sample analysed; 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 data before given, see page 308. 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 sulphuric or brown acid. At the end of this paper, will be found a table of Dr. Ure's, showing the amount of real sulphuric acid contained in oil of vitriol of various densities. The "chamber" or "brown acid" of the manufacturers' of sp. gr. 1.7, is the cheapest and most generally used article for the manufacture of superphosphate of lime; 100 pounds of this acid contains 65 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 carboy, 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 longer. 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 fragrance 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, ruta baga, young trees, |