FERTILIZERS IN THE ROCKS. 63 



sed in the rocks themselves, in combination with organic remains. 

 All animal matter contains more or less of the phosphates, and 

 hence as these remains of organic bodies are still enclosed in our 

 rocks, we conceive that it must be locked up still in these sedi- 

 mentary masses. Bearing upon this subject, we may state that 

 the recent examinations of Mr. Benjamin Silliman, Jr., of the co- 

 rals, bears out this conjecture. Thus, Mr. Silliman found as much 

 as nine or ten per cent of the phosphate in some of his examinations 

 of the corals. Is this substance likely to be lost when these corals 

 are enclosed in their rocky beds ? If a limestone with a few per 

 cent of this substance could be found, its value for agricultural 

 purposes would be greatly increased. 



All these facts and suggestions have a practical bearing, and w^e 

 are anxious the farmer should be able to avail himself of all the 

 aids which science can afford. On this subject we propose to give 

 from time to time, the results of our inquiries. 



Phosphate of lime, we have already stated in another article, 

 occurs in the white limestones, such as those in Orange, St. Law- 

 rence, and Jefferson counties. Of the origin of this substance 

 there is a difference of opinion, and we hope we may be excused 

 for occupying a short space in our columns in the discussion of this 

 point, although it has no practical bearing ; yet we believe that all 

 enlightened agriculturists will be pleased to know as much as pos- 

 sible of those subjects which relate to the history of important 

 materials — one so important as phosphate of lime. 



Mr. James D.Dana, [Joicrnal of Science p. 135, Vol. XL VII,] 

 maintains that the phosphate of these limestones, although now in 

 superbly finished crystals, originated from organic structures, from 

 corals, which after being enclosed in their rocky prison, were ex- 

 posed to intense heat, and hence were decomposed ; the phosphate 

 of lime separating from other matters composing the original co- 

 ral, assumed the form and condition we now find it. In this expo- 

 sure, the whole rock is supposed to have undergone an entire 

 change, passing from an earthy to a liighly crystalline mass. The 

 idea is, that these rocks were originally deposited in the ocean, 

 enclosing in their several beds and layers the organic bodies which 

 then lived upon those beds; or, in that ocean — mere sediments — 

 but by the exposures we have already spoken of, have been chang- 

 ed and brought to the condition we now find them. Magnesia is 



