SOIL. 



ftand ; fome glafs-bottles ; HefTian crucibles ; porcelain or 

 queen's ware evaporating bafons ; a Wedgewood pelUe and 

 mortar ; fome filters made of half a (heet of blotting-paper, 

 folded fo as to contaui a pint of liquid, and greafed at the 

 edges ; a bone-knife, and an apparatus for colleAing and 

 meafuring aeriform fluids. And the chemical fubllances or 

 re-agents required for feparating tiie conllituent parts of the 

 foil are, muriatic acid (fpirit oif fait), fulplmric acid, pure 

 volatile alkali diffolved in water, folution of prufiiat of 

 potafh and iron, fuccinate of ammonia, foap-ley, folutions 

 of carbonate of ammonia, of muriate of ammonia, folution 

 of neutral carbonate of potalh, and nitrate of ammonia. 

 An account of the nature of thefe bodies and their effefts 

 may be found in Dr. Thomfon's Syllem of Chemiftry, and 

 Henry's Epitome ; and the re-agents are fold together with 

 the inftruments mentioned above, by Mr. Knight, Foiler- 

 lane, Cheapfide, arranged in an appropriate cheil. 



2. M»i]e of colUning Soils for ylnalyfis — In cafes where 

 the general nature of the foil of a field is to be afcertained, 

 fpecimens of it Ihould be taken from different places, two 

 or three inches below the furface, and examined as to the 

 fimilarity of their properties. It fometimes happens, that 

 upon plains, the whole of the upper ilratum of the land is 

 of the fame kind, and in this cafe one analyfis will be fufii- 

 •cient ; but in vallies, and near the beds of rivers, there are 

 Tery great differences, and it now and then occurs that one 

 part of a field is calcareous, and another part filiceous ; and 

 in this cafe, and in analogous cafes, the portions different 

 from each other fliould be feparately fubmitted to experi- 

 ment. Soils, when collefted, if they cannot be imme- 

 diately examined, fliould be preferved in phials quite filled 

 with them, and clofed with ground-glafs (toppers. The 

 quantity of foil moft convenient for a perfeA analyfis, is 

 from two to four hundred grains. It fliould becollefted in 

 dry weather, and expofed to the atmofphere till it becomes 

 dry to the touch. The fpecific gravity of a foil, or the re- 

 lation of its weight to that of water, may be afcertained by 

 introducing into a phial, which will contain a known quantity 

 of water, equal volumes of water and of foil, and this may 

 be eafily done by pouring in water till it is half full, and 

 then adding the foil till the fluid rifes to the mouth ; the 

 difference between the weight of the foil and that of the 

 water will give the refult. Thus, if the bottle contains 

 400 grains of water, and gains zoo grains when half filled 

 with water and half with foil, the fpecific gravity of the 

 foil will be 2 ; that is, it will be twice as heavy as water : 

 and if it gained 165 grains, its fpecific gravity would be 

 182 J, water being 1000. It is of importance that the fpe- 

 cific gravity of a foil fliould be known, as it affords an in- 

 dication of the quantity of animal and vegetable matter it 

 contains ; thefe fubllances being always moft abundant in 

 the lighter foils. The other phyfical properties of foils 

 fliould likewife be examined before the analyfis is made, as 

 they denote, to a certain extent, their compofition, and 

 ferve as guides in direfting the experiments. Thus, filiceous 

 foils are generally rough to the touch, and fcratch glafs 

 when rubbed upon it ; ferruginous foils are of a red or yel- 

 low colour ; aluminous foils adhere ftrongly to the tongue, 

 and emit a ilrong earthy fmell when breathed on ; and cal- 

 careous foils are foft, and much lefs adhefive than aluminous 

 foils. 



3. Mode of afcerta'ining the Quantity of Water of Alforption 

 in Soils. — Soils, though as dry as they can be made by 

 continued expofure to air, in all cafes ftill contain a con- 

 fiderable quantity of water, which adheres with great 

 cbftinacy to the earths and animal and vegetable matter, 

 and can only be driven off from them by a confiderabk 



degree of heat. The firft procefs of analyfis is, to free the 

 given weight of foil from as much of this water as poffible, 

 without, in other refpefts, affeAing its compofition ; and 

 this may be done by heating it for ten or twelve minutes 

 over an Argand's lamp, in a bafon of porcelain, to a tem- 

 perature equal to 300° Fahrenheit. In feveral experiments, 

 in wliich this procefs has been carried on by diltillation, he 

 has found the water that came over pure, and no fenfible 

 quantity of other volatile matter was produced. And in 

 cafe a thermometer is not ufed, the proper degree may be 

 eafily afcertained, by keeping a piece of wood in contaft 

 with the bottom of the difli ; as long as the colour of the 

 wood remains unaltered, the heat is not too high ; but 

 when the wood begins to be charred, the procefs muft be 

 flopped. A fmall quantity of water will perhaps remain 

 in the foil, even after this operation, but it always affords 

 ufeful comparative refults ; and if a higher temperature 

 were employed, the vegetable or animal matter would 

 undergo decompofition, and in confequence the experiment 

 be wholly unfatisfaftory. The lofs of weight in the procefj 

 fliould be carefully noted, and when in four hundred grains 

 of foil it reaches as high as fifty, the foil may be confidered 

 as in the greatelt degree abforbent, and retentive of water, 

 and will generally be found to contain a large proportion 

 of aluminous earth. When the lofs is only from twenty to 

 ten, the land may be confidered as only flightly abforbent 

 and retentive, and the filiceous earth as probably moft 

 abundant. 



4. The Separation of Stones, Gravel, and vegetable Fibres from 

 Soils. — None of the loofe Hones, gravel, or large vegetable 

 fibres, fliould be divided from the pure foil, till after the 

 water is drawn off ; for thefe bodies are themfelves often 

 highly abforbent and retentive, and in confequence influence 

 the fertility of the land. The next procefs, however, after 

 that of heating, fliould be their feparation, which may be 

 eafily accomphflied by the fieve, after the foil has been 

 gently bruifed in a mortar. The weights of the vegetable 

 fibres of wood, and of the gravel and Itones, fliould be fepa- 

 rately noted down, and the nature of the laft afcertained ; 

 if calcareous, they will effervefce with acids ; if filiceous, 

 they will be fufficiently hard to fcratch glafs ; and if of the 

 common aluminous clafs of itones, they will be foft, eafily 

 fcratched with a knife, and incapable of effervefcing with 

 acids. 



5 . Separation of the Sand and Clay, or Loam, from each other. 

 — The greater number of foils, befides gravel and ftones, 

 contain larger or fmaller proportions of fand of different 

 degrees of finenefs ; and it is a neceffary operation, the 

 next in the procefs of analyfis, to detach them from the 

 parts in a ftate of more minute divifion, fuch as clay, loam, 

 marie, and vegetable and animal matter, and the matter 

 foluble in water. This may be effefted in a way fufficiently 

 accurate, by boiling the foil in three or four times its 

 weight of water, and, when broken down and cool, by 

 agitating the parts of the foil in the water, and then letting 

 them relt. In this cafe, the coarfe fand will generally 

 feparate in a minute, and the finer in two or three minutes, 

 whilft the minutely divided earthy, animal, or vegetable 

 matter will remain in a flate of mechanical fufpenfion for a 

 much longer time ; fo that by pouring the water from the 

 bottom of the vefl'el, after one, two, or three minutes, the 

 fand will be principally feparated from the other fubltances, 

 which, with the water containing them, muft be poured 

 into a filter, and after the water has paffed through, col- 

 leAed, dried, and weighed. The fand muft likewife be 

 weighed, and their refpeftive quantities noted down. 

 The water pf lixiviation mult be preferved, as it will be 



found 



