440 The Neglect of Chemistry hy Practical Farmers. 



gravel or sand" and "Fine matter." These are intended to 

 show roughly the textural differences of the soils, the " Fine 

 matter " being the impalpable matter that is separated by v. ash- 

 ing, and the " Coarse matter " the remainder. 



I have also given the quantity of each ingredient contained in 

 one acre of the soil, to the depth of one foot, when dried in the 

 air, in order that the practical farmer may form some idea of the 

 extensive manner in which Nature carries on her operations ; 

 indeed, I have no hesitation in asserting that there is not any one 

 who could form the slightest conception of these quantities by a 

 mere inspection of the proportional parts in 100, as given in an 

 analysis. I have taken for the basis of my calculation the mean 

 specific gravity of sixteen different soils when dried in the air, as 

 ascertained by Dr. Krocker, and published in the last edition of 

 Liebig's work, which gives 3000 tons, more or less, as the weight 

 of one acre of soil, one foot deep, when dried in the air. I am 

 aware that this result m^ore than doubles the usual estimate of 

 Professor Way, which is, that one inch of soil weighs 100 tons 

 per acre ; this I think may in some degree be accounted for by 

 supposing that Professor Way's estimate refers to a soil in its 

 natural state when cultivated. Mr. Hall, of Liverpool, was, I 

 believe, the first person to draw attention to the necessity of 

 showing the amount of each mineral ingredient contained in one 

 acre of soil ; and the conclusion that some writers have drawn 

 from the fact, that a very minute decimal proportion per cent, 

 amounts to a very considerable weight in pounds when calculated 

 for an acre, is, that the analyses hitherto published have not been 

 sufficiently minute, even when calculated to three places of 

 decimals. 



There seem at first sight strong gi'ouncls for agreeing vath this 

 proposition ; but when we come to consider that it would be 

 manifestly impossible to obtain a small portion of soil for analysis, 

 however carefully mixed, that should be a perfect average ol the 

 whole acre ; and also that no analysis of a few hundred grains, 

 however carefully performed, can be absolutely depended on to 

 more than the first' place in decimals; the opposite conclusion 

 would appear to be nearer the truth, that to calculate to more 

 than one place of decimals is a waste of time for all practical 

 purposes, and also tends to encourage a false confidence in the 

 results. In the case of the soluble salts and of other important 

 ingredients that may exist only in very minute proportion (gene- 

 rally recorded as a "trace"), it might perhaps be as w^ell to 

 operate upon a much larger quantity of the soil, in order that a 

 sufficient quantity of the salts, &c., might be obtained, to give 

 trustworthy results ; when again analysed, to show the individual 



