ANALYSIS OF SOILS, 33 



and the relations between the external and chemical qualities 

 of foils, he will feldom find it neceflary to perform, in any 

 one cafe, all the procelfes that have been defcribed. When 

 his foil, for inftance, contains no notable proportion of cal- 

 careous matter, the action of the muriatic acid IX. may be 

 omitted. In examining peat foils, he will principally have to 

 attend to the operation by fire and air X. ; and in the analyfis 

 of chalks and loams, he will often be able to omit the ex- 

 periment by fulphuric acid XI. 



In the firft trials that are made by perfons unacquainted 

 with chemiftry, they muft not expect much precifion of refult. 

 Many difficulties will be met with ; but in overcoming them, 

 the mod ufeful kind of practical knowledge will be obtained ; 

 and nothing is fo instructive in experimental fcience, as the * 



detection of raiftakes. The correct analyft ought to be well 

 grounded in chemical information ; but perhaps there is no 

 better mode of gaining it, than that of attempting original 

 inveiligations. In purfuing his experiments, he will be con- 

 tinually obliged to learn from books, the hiftory of the fub- 

 ftances he is employing or acting upon ; and his theoretical 

 ideas will be more valuable in being connected with practical 

 operation, and acquired for the purpofe of difcovery. 



XVI. On the Improvement of Soils, as connected with the 

 Principle of their Composition. 



. In cafes when a barren foil is examined with a view to its Improvement of 

 improvement, it ought in all cafes, if poffible, to be compared known com- 

 with an extremely fertile foil in the fame neighbourhood, and portion of fer- 

 in a fimilar fituation: the difference given by their analyfes ^£ 

 would indicate the methods of cultivation j and thus the plan 

 of improvement would be founded upon accurate fcientific*. 

 principles. 



If the fertile foil contained a large quantity of fand, in pro- 

 portion to the barren foil, the procefs of amelioration would 

 depend limply upon a fupply of this fubftance ; and the method 

 would be equally fimple with regard to foils deficient in clay 

 or ealcareous matter. 



In the application of clay, fand, loam, marie, or chalk to 

 lands, there are no particular chemical principles to be ol- 

 f<prved; but when quick lime is ufed, great care muft be taken 

 that it is not obtained from, the magnefzan limefione \ for in 



this 



