INORGANIC ELEMENTS OF MANURES AND CROPS. 365 



who ascribed to this cause the present sterility of various parts of 

 Northern Africa and of Asia Minor, as well as of Sicily, which for 

 a long succession of years was the granary of Italy. Rome un- 

 questionably contains in its catacombs quantities of phosphorus from 

 all the countries of the earth. 



Professor Liebig, in insisting with the greatest propriety on the 

 useful part played by alkaline bases and saline matters in vegetation, 

 has shown the necessity of taking inorganic substances into serious 

 consideration in discussing rotations. It is long since I came to the 

 same conclusion myself; but it strikes me, that to be truly profitable, 

 such a discussion must necessarily rest on analyses of the ashes of 

 plants which have grown in the same soil, and been manured with 

 the same dung, the contents of which in mineral elements were al- 

 ready known. There is in fact a kind of account current to be es- 

 tablished between the inorganic matter of the crop and that of the 

 manure. Although I give every credit to the fidelity of the analyses 

 of vegetable ashes that have been published up to the present time, 

 I have not felt myself at liberty to make use of any of them in the 

 direction which I now indicate. • I have not thought that it would be 

 fair or reasonable to contrast such heterogeneous compounds, as the 

 ashes of plants grown at Geneva and Paris, under such dissimilar 

 circumstances, with those of vegetables produced on a farm of Al- 

 sace, where the point to be explained, through the results of this 

 contrast, had reference to a particular series of agricultural phenom- 

 ena. And then my business was not merely with the scientific ques- 

 tion ; the manufacturing or commercial element in the consideration 

 also touched me. I had to ascertain how I was likely to stand at 

 some future time, did I presume to act upon the conclusions to which 

 I came. There was nothing for me therefore but to analyze the 

 ashes of the several vegetables which entered as elements into the 

 rotation followed at Bechelbronn, but confining my inquiries to that 

 portion of the vegetable which is looked upon particularly as the 

 crop, so much of the plant as remains on the ground and is turned in 

 again, of course taking nothing from it.* 



The ashes examined were almost all from the crops of 1841, two 

 analyses having generally been made of each substance : and here 

 I ought to say, that in this long and tedious labor, in which I spent 

 nearly a whole year, I was most ably seconded by Mr. Letellier. By 

 way of preface, I should say that in these analyses, losses will fre- 

 quently be apparent, which for the most part exceed the limits that 

 in the present day are tolerated in the more careful operations of the 

 laboratory. These deficiencies, which puzzled me a good deal at 

 first, I by and by discovered to proceed from the difficulty of incin- 

 erating certain vegetable substances completely. When they abound 

 in alkaline salts, they leave ashes that melt so readily, that it becomes 

 difficult to prevent their agglutination, and the charcoal that is not 

 consumed is then effectually protected against any further action of 

 the fire. There is nothing for it in such cases but to incinerate at 

 the lowest temperature possible, and then a little moisture is apt to 

 be left ; the charcoal, however, is the substance that occasions the 



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