DISAPPEARAN-CE OF CARBONATE OF LIME FROM SOIL. 79 



obtained, of coarse and fine, is eight grains in one thousand, or 

 about one-fourth of the original proportion. All the remainder 

 had changed its form, or otherwise disappeared, in the few years 

 that had passed since the application.* 



{ Another similar trial of this soil from the same ground was re- 

 peated in July, 1842, which showed that the finely divided carbo- 

 nate of lime, then remaining, was in quantity so small as to be 

 barely perceptible and appreciate. The land had then remained 

 undisturbed by tillage for nine months ; and some scattered frag- 

 ments of shells were exposed to view on the surface generally. 

 For the obvious reasons stated in the preceding paragraph, there 

 will always appear an over-proportion of such fragments, upon the 

 surface of land not recently ploughed ; for this reason, as on two 

 of the three former trials, the upper half-inch of surface soil was 

 thrown aside, and the sample for examination taken immediately 

 below. Of this, 2400 grains yielded two grains only of small 

 fragments of shells, and less than one grain of finely divided car- 

 bonate of lime ; whereas seventy-two grains had been the original 

 quantity furnished to the soil. This result, with those of the 

 earlier trials, agree precisely with what would be expected from the 

 action of acid in soil, and cannot be satisfactorily explained by 

 any other doctrine.f 1842.] 



[* An experiment conducted by Lampadius, and quoted by Johnston in 

 his recent work, is very like the above, and shows like results. " He 

 mingled [the carbonate of] lime with the soil of a piece of ground till it 

 was in the proportion of 1.19 per cent of the whole, and he determined 

 subsequently by analysis, the quantity of lime it contained in each of the 

 three succeeding years. 



1st year it contained 1.19 per cent, of carbonate of lime. 



2d year . . 0.89 " 



3d year . . 0.52 " " 



4th year . . 0.24 " " 



But from these premises, so similar to mine, it must be admitted that 

 Prof. Johnston arrives at a very different conclusion. He takes the gradual 

 lessening of the carbonate as proving the entire removal from the soil of so 

 much lime; while I considered it as showing merely the change from the 

 carbonate to some other salts of lime. 1849.] 



[f Even of this very small amount of fragments of shells found (2 grains), 

 more than half was of the very hard gray shells (oyster and scallop), 

 which seem almost indestructible in soil. They must contain some chemi- 

 cal ingredient which enables them to withstand the acid or other corroding 

 action of soil, to which all the white fossil sheffs, whether hard or soft, so 

 readily yield in the course of time. I recently observed a most striking 

 proof of this well known general fact of the long durability of these gray 

 shells, and consequently their comparative worthlessness as a manure. On 

 like soil to the subject of the above trials, and near the same spot, I 

 recently (1842) found a small and thin but well-marked oyster-shell (Ostrea 

 Viryiniana}, apparently as perfect and as well preserved as when it was 

 dug up, and which was a good characteristic specimen of the kind, and, as 



