372 Report on a re-examination of the 



among the most valuable of our soils ; and yet I doubt whether they produce as 

 much at one crop as many other soils ; though the others perhaps require more 

 labor in cultivation. 



The amount of soluble and insoluble geine obtained by Dr. Dana's method of 

 analysis, ought to correspond pretty nearly with the amount of organic matter ob- 

 tained by the old method ; and by comparing the two tables of results that have 

 been given, it will be seen that such is the fact. Several circumstances, however, 

 besides errors of analysis, will prevent a perfect agreement. In the first place, by 

 the old method of analysis, 100 grains of the soil are weighed before expelling the 

 water of absorption ; but by the new method, not until after its expulsion. Again, 

 by the old method only the very coarse parts of the soil are separated by the sieve : 

 but a fine sieve is used by the new mode, and this removes nearly all the vegeta- 

 ble fibre, which by the other method is reckoned a part of the organic matter. 

 Other causes of difference might be named : and hence we ought not to expect a 

 perfect agreement in the results of the two methods. 



The three next columns in the Table contain the salts of lime in our soils. I 

 have already described the infrequency of the carbonate; but very different is the 

 case with the sulphate and the phosphate which were found in greater or less 

 quantity, in every soil analysed. In respect to the sulphate of lime, or gypsum, 

 it may not be unexpected that we should find it in all soils, since we know it to 

 occur in all natural waters throughout the state ; and we cannot conceive of any 

 other source from which the water could have derived it, except the soil. But the 

 phosphate of lime has generally been supposed to be much more limited, nay to be 

 scarcely found in soils, except where animal substances-have been used for manure. 

 It is possible that in all the soils which I have analysed, such might have been its 

 origin, though not very probable. Yet there is strong reason to believe, that this 

 salt is a constituent of all soils in their natural state. The arguments on this sub- 

 ject are stated so ably by Dr. Dana that I need only quote from his letter. 



" When we consider that the bones of all graminivorous animals contain nearly 

 50 per cent, of phosphate of lime, we might be at liberty to infer the existence of 

 this principle, in the food, and, consequently, in the soil, on which these animals 

 graze. If we look at the actual result of the analysis of beets, carrots, beans, peas, 

 potatoes, asparagus, and cabbage, we find phosphate of Ihne, magnesia, and potash, 

 varying from 0.04 to 1.00 per cent, of the vegetable. Indian corn too, by the anal- 

 ysis of the late Professor Gorham, of Harvard College, contains 1.5 per cent, phos- 

 phate and sulphate of lime. It may be said that this is all derived frohi the manure. 

 We shall see by and by. Let us look at the extensive crops often raised where 

 man has never manured. Rice, wheat, barley, rye, and oats, all contain notable 

 portions of phosphate of lime, not only in the grain but in the straw, and often in 

 the state of superphosphates. The diseases too, ej-got and smut, show free phospho- 

 ric acid. Can it be that, owing to certain electrical influences of the air, in partic- 

 ular seasons, lime is not secreted by the plant to neutralize the free acid ? May 

 not this be a cause of smut and ergot ? Does it not point out a remedy ? Take too 

 the cotton crop of our country. What vast quantities of phosphates do we thus 

 annually draw from the soil .'' Cotton gives one per cent, ashes, of which 17 per 

 cent, is composed of phosphate of lime and magnesia. The like is true of tobacco. 

 It contains 0.16 per cent, of phosphate of lime. If we turn to the analysis of forest 

 trees, we find that the pollen of the pinus ahies, wafted about in clouds, is composed 

 of 3 per cent, phosphate of lime and potash. May not this too be one of nature's 

 beautiful modes of supplying phosphoric acid to plants and to soils.? If, as the late 

 experiments of Peschier have proved, sulphate of lime, in powder, is decomposed 

 be growing leaves, the lime liberated, and the sulphuric acid combining with the 



