On tlip Application of Geology to Agriculture. 275 



stratification of the earth may be made subservient to the 

 systematic arrangement of those facts^, trials, and experiments 

 which societies Hke this will encourage and collect. It is quite 

 clear that the results of the best local practice on different soils 

 have never yet been generalised, nor even had the benefit of a 

 judicious selection. Certain soils are so obviously connected with 

 their bases, that we need scarcely ask how geology and agriculture 

 are linked together ; and to use Dr. Smith's own words, The 

 strata succeed each other in a certain order, and, being delineated, 

 a knowledge of the strata becomes the natural and safe foundation 

 of improvement ; and if agricultural chemistry be ever success- 

 fully applied to the practical purposes of agriculture, it must be 

 by proceeding with the chemical analysis of soils along the range 

 of each stratum." 



Proceeding then on the positive basis established by the science 

 of geology, we may spread on that base a new layer of facts, with 

 ready references to them for local use or general reasoning. 



Arranged upon maps they may be readily seen, compared, and 

 generalised. When any two parties have made experiments 

 upon the same stratum, no matter which, a comparison can then 

 be made. Chemists will thus be called into action, and as the 

 different limestone soils and clays, &c. vary, so in lieu of the 

 general terms sandy, loamy, or clayey, which are only generic 

 distinctions of little use, specific distinctions derived from geo- 

 logical terms will hereafter be used. 



John V. B. Johnstone. 



Hachness. near Scarborough^ 

 Nov. Uth, 1839. 



XXVIII.— On the Use of Saltpetre as Manure, By George 



KiMBERLEY, Esq. 



To take a retrospective view of the use of saltpetre (or nitrate of 

 potash) as a manure, may well at the present day be considered 

 superfluous, but it may not be amiss to remind the reader that 

 saltpetre was known and used as long since as the time of Virgil, 

 and we find a notice or hint of the effects of nitre or nitrous water 

 worth the attention of farmers in the Sylva of Bacon, published 

 in the year 16/0. Evelyn also understood some of the advantages 

 of saltpetre as a manure ; it has also been tried and reported on 

 by various authors down to the year 1828, when, in No. 3 of the 

 ' Quarterly Journal of Agriculture' we find an account of its use by 

 William Hawkins, Esq., of Hitchin, Hertfordshire, Avhere the 

 experiments appear very satisfactory and conclusive. Since that 



