SOIL. 



much of the irony part may be feparated, by pouring it, 

 when well dried, into fpirit of fait ; from which the iron 

 may afterwards be feparated by alkalies or chalk. And 

 akin to this are certain vitriolic foils, which, when fteeped in 

 water, impart to it the power of reddening fyrup of 

 violets. Thefe are generally of a blue colour, but redden 

 when heated. 



Further, it has been remarked by a late writer, that in 

 proportion as the clayey principle difappears, they recede 

 from foils of that kind, and that of courfc the nearer the 

 quahty of the clayey matter comes to that of the others, 

 the itronger and heavier the loamy foils mull be. And that 

 the differences in the lightnefs and friability of the foils of 

 this clafs, in a great meafure, depend on the relative propor- 

 tions of the other ingredients. Where the calcareous in- 

 gredient greatly exceeds thofe of the fandy or gravelly kinds, 

 they are neither fo light nor fo pulverizable as where they 

 are nearly equal, or where the fandy or gravelly matters con- 

 fiderably predominate over it. In the latter cale, indeed, 

 fuch foils are formed as have been denominated by pr. lical 

 farmers light and hungry, efpecially where the arthy b.d or 

 ftratum thus produced is but of little depth, 'nd relts on 

 a gravelly or flinty bottom or fub-foil. It is alfo added, that 

 the variety in the colours of foils of the loamy kind, feems, 

 in fome inftances, to be produced bv the union or mixture of 

 metallic fubftances in greater or lefs proportions, and in 

 more clofe or more lax itates of combination with them ; in 

 others, by the prevalence of acid impregnations. The co- 

 lour in the firft cafe is for the moll part reddiih, approach- 

 ing to brown ; in the latter it is commonly blueifli, changing 

 by heat to a flight red. But thefe are not, he fuppofes, the 

 only caufes that influence the colour of thefe foils ; they are 

 much altered in their appearances, as well as other qualities, 

 by the different proportions of vegetable or animal matter 

 which they contain, and the different ftates of decorapofltion 

 and decay to which they have been carried by lenc^th of time, 

 cultivation, and other means. In fituations, it is faid, 

 where this fort of foil has been but little dilturbed, and 

 confequently little changed by the artificial additions of 

 either animal or vegetable fubllances, and thofe which it 

 naturally contained not having advanced to the itage of 

 perfeft folution and decay, it is generally found of a light 

 brown or hazel colour ; but where much culture has been 

 employed for a length of time, and large applications of 

 animal and vegetable matters frequently made, the natural 

 and artificial materials of thefe kinds, having proceeded 

 more nearly to the llate of perfeft diflblution and deitruc- 

 tion, it has an appearance that approaches to that of black. 

 And it is added, that from thefe various circumllances, the 

 properties of the foils are likewife confiderably altered and 

 afFeAed. Such foils of this kind as are met with in extenfive 

 trafts on the borders of the fea, and of large rivers com- 

 municating with it, are generally rich and fertile, being 

 moftly compofed of a fine fort of fand, calcareous matter 

 in a high ftate of tenuity from the attrition or rubbing down 

 of ditfereiit kinds of (hells and other marine produftions, and 

 a rich matter proceeding from the difiolution of various 

 luxuriant fea plants, and innumerable forts of animal exuvise. 

 Thefe alluvial materials being all gradually depofited and 

 incorporated with the natural loamy earth of the fituations 

 in which they are found. 



There are foils of this fort, in particular fituations near 

 the fea-coafts, which are extremely rich, being a great deal 

 conllituted or compofed of layers of oyfter and cockle-fliells, 

 in combination with their earthy matters, and much impreg- 

 nated with marine fait from the overflowings of the fea, 

 v/hich feems to have been highly beneficial to them, when 



afted upon, for fome length of time, by the air of the aU 



raofphere, in the produftion of grain as well as other crops. 

 In thefe cafes, this faline quality would appear to be en- 

 tangled in a peculiar fort of loamy Inhftance, very different 

 from any which are met with in upland fi: nations. The 

 richefl; loamy foils in fuch places are moftly comp-v(ed, in a 

 great meafure, of fand in mixture with a portion of clay, i 

 and are, from this quantity of fand, very friable in their \ 

 nature. But with the foils in thefe particular cafes, it is 

 very different ; as whatever degree of friability they may 

 pofTefs, feems to arife from the fermentative power, which 

 is caufed by the aftion of th; atmofphere on fubftances that 

 abound with mucilaginous matters. They fail, it is faid, 

 when expofed to the changes of the weather, into dies, and 

 are more like the cryftallized forms of mud drying in the 

 fun, than the crumbling loofenefs of common loams. There 

 is very httle a; nearance of any fand in them ; the particles 

 of which they .ire compofed are fo very fine, that it would 

 be readily iiv.agined, they would eafily become an impalpable 

 powder ; but, on the contrary, they are capable of fuch 

 adhefion, that a clod will often become very hard. Confe- 

 quently they appear to be compofed of clay, very fine fand, 

 a mucilaginous principle which ferments with rain and 

 warmth, and the faline quality which is derived from their 

 origin and peculiarity of fituation. When crumbled in the 

 hand, they yield a Itrong fcent, fo that the volatile alkali 

 would probably be difcovered by chemical trials, it is 

 thought, in them. Soils of this loamy kind are met with 

 in Foulnefs ifland, in Effex, and fome other fimilar fituations. 

 Their natural fertility is often fo very great, that the farmers 

 are but little attentive to manure ; nor is it commonly 

 ventured for any fort of grain, as it throws up too much 

 ftraw, without increafing the quantity of corn. It might, 

 however, probably be applied for beans, or cabbages, where 

 they were the previous crops, with much advantage. 



This fort of excellent loam is fuppofed utterly incapable 

 of being formed or attained by any kind of artificial means : 

 the great elaboratory of nature in this, as in fo many other 

 cafes, leaves, it is thought, the utmoft Ikill of the chemical 

 farmer at a vaft diftance. 



The chemical analyfis of this fort of foil, as given in the 

 work already mentioned, by Mr. Somerville, may (hew ItiU 

 more fully the properties which are poiieffed by this kind of 

 land. 



From the experiments of this ingenious writer it would 

 appear, that the principal conftituent parts of the different 

 kinds ef loam, upon which they were tried, are vegetable 

 and calcareous earths, oil, alkaline falts, and an inconfider- 

 able quantity of iron. The deep black loams feem to con- 

 tain confiderably more oil than any of the other two, but 

 lefs alkali and calcareous earth ; which, in fome meafure, 

 accounts for the inadlive nature of fome foils of that de- 

 fcription, which, by no means, yield crops equal to what 

 might be expefted from their appearance. The hazel- 

 coloured loam contains lefs oil than the black, but a greater 

 proportion of alkaline falts and calcareous earth ; owing to 

 which, all the loams of that defcription in Eaft Lothian are 

 more aftive, and produce better crops than the former. The 

 light loams, from the circumftance of their containing lefs 

 oily and more alkaline and calcareous matter, are the moft 

 aftive, and are commonly termed /harp lands, by the farmers 

 in that diilrift. 



Further, thefe foils being, in general, lefs tenacious or 

 more friable and mellow than clays, are capable of being 

 more eafily improved with lefs expence and labour of team, 

 and alfo at any feafon of the year. The manure proper for 

 fuch foils varies according to their relative degree of fer- 



tibty, 



