LIME IN WOOD ASHES. 



81 



9th. All wood ashes contain salts of lime (and most kinds in 

 large proportions), which could have been derived from no other 

 source than the soils on which the trees grew. The lime thus ob- 

 tained from ashes is principally combined with carbonic acid, and 

 partly with the phosphoric, forming phosphate of lime. The 

 table of Saussure's analyses of the ashes of numerous plants,* is 

 sufficient to show that these products are general, if not universal. 

 The following examples of some of my own few examinations indi- 

 cate that ashes yield calcareous earth in proportions suitable to 

 their kind, although the wood grew on soils destitute of that in- 

 gredient as was ascertained with regard to each of these soils. 



The potash was first carefully taken out of all these samples. 

 The remaining solid matter was silicious sand and charcoal ; the 

 proportion of the latter varying according to the degree of heat 

 used in burning the wood, which was not permitted to be very 

 strong, for fear of converting the calcareous earth into quick-lime. f 



* Quoted in Davy's Agr. Chem. Lecture 3. 



f [In the first sketch and earliest publication of this essay in the 

 " American Farmer," of 1821, the statement of the calcareous contents of 

 ashes, similar to the above, was followed by the following remark: "The 

 results of the few examinations I have made do not confirm the opinion 

 [or results] of De Saussure, that ashes yield quantities of calcareous earth 

 somewhat proportioned to the quantities contained in the soils from which 

 they were taken. But they show, in different plants, quantities suited to 

 the soil which each prefers. Thus, of three kinds of ashes from the same 

 soil, those of pine gave 5, of whortleberry 4, and of locust 51 per cent, 

 of carbonate of lime, and [somewhat] similar proportions of other salts 

 of lime." (Am. Far. iii., p. 316.) In all the succeeding separate editions 

 of the essay, this remark was suppressed, being deemed too presumptuous 

 for me to use. But I may now dare to reassume the position, since John- 

 ston denies the accuracy of De Saussure's and also of Berthier's analyses, 

 which concur in the conclusions referred to, aud also the correctness of these 



