1838] 



FARMERS' REGISTER. 



619 



always denotes a consi(lernl)lo proportion of vege- 

 table mailer. In cases when it is neeessary that 

 the e.xperinietiis shnnlii lie very quickly [terlornied, 

 the destruction ol" the dei'oniposahle substances 

 may be assisted by ihe ajrency orniiraie oi'annno- 

 riiac, which at the lime ofiirnilion maybe thrown 

 <rradually upon the healed mass, in the qaanliiy of 

 twenty <rriiiiis for every hundred of residual soil. 

 it accelerates the dissipation of the animal and 

 vegetable matter, which it causes to be converted 

 into elasiic fluids; and it is itsell at the same time 

 decomposed and lost. 



7. The substances remaining after the destruc- 

 tion of the vegetable and animal matter are gene- 

 rally minute particles of earl by matter, containing 

 usually alumina and silica, with combined oxide ol" 

 iron, or of mnnganesum. 



To separate these from each other, the solid 

 matter should be boiled lor two or three hours with 

 sulphuric acid, diluted with four limes its weight 

 of water: the quantity of the acid should be regu- 

 lated by thequantily o( solid residuum lobe acted 

 on, allowing for every 100 grains 2 drachms or 120 

 grains of acid. 



The substance remainiriir after the action of the 

 acid may be considered as siliceous; and it must 

 be separaled, and its weight ascertained, after 

 washing and drying in the usual manner. 



The alumina and the oxide of iron and manga- 

 neeum, if any exist, are all dissolved by the sul- 

 phuric acid: they may be separated by succinate 

 of ammonia, added to excess, which throws down 

 the oxide of iron ; and by soap lie, which will 

 dissolve'the alumina, but not the oxide of manga- 

 nesum; the weights of the oxides ascerlained after 

 they have been heated to redness will denote their 

 quanlities. 



Should any magnesia and lime have escaped 

 solution in the muriatic acid, they will be found 

 in the sulphuric acid ; this, however, is rarely the 

 case; but the process for detecting them and 

 acertaining their quantities, is the same in both 

 instances. 



The method of analysis by sulphuric acid is 

 sufficiently precise for ail usual experiments ; but 

 if very great accuracy be an ofiject, dry carbonate 

 of poiassa must beemployed as the agent, and the 

 residuum of the incineraiion (6) :nust be heated 

 red (ijr half an hour, with four times its weight of 

 this substance, in a crucible of silver, or ofvvell- 

 baked porcelain. The mass obtained must be 

 dissolved in muriatic acid, and the solution eva- 

 porated till it is nearly solid ; distilled water must 

 then be added, by which the oxide of iron and all 

 the earths, except silica, will be dissolved in com- 

 bination as muriates. The silica, afier the usual 

 process of lixiviation, must be healed red; the 

 other substances may be separaled in the same i 

 manner as li-om the muriatic and sulphuric solu- ' 

 tions. 



This process is the one usually employed by 

 chemical philosophers lor the analysis of siones. 



8. If any saline matter, or soluble vegetable or 

 animal mailer is suspected in the soil, it will be 

 found inthe water of lixiviation used for separating 

 the sand. 



This water must be evaporated to dryness in a 

 proper dish, at a heat below its boiling point. 



If the solid matter obtained is of a brown color 

 and inflammable, it may be considered as partly 

 vegetable extract, if its smeil, when exposed to 



heat, be like that of burnt leathers, it contains ani- 

 mal or albuminous matter; if il be white, crystal- 

 line, and not destructible by heat, it may be consi- 

 dered as principally saline mailer; the na'ureof 

 which may be known by the tests already de- 

 scribed. 



9. Should sulphate or phosphate of lime be 

 susjiected in the entire soil, the detection of them 

 requires a particular process upon it. A given 

 weight of it, for instance, 400 grains, nmst be 

 healed red lor half an hour in a crucible, mixed 

 with one-third of powdered charcoal. The mix- 

 ture must be boiled for a quarter of an hour, in 

 a-half pint of water, and the fluid collected through 

 the filler, and exposed for some days lo the atmo- 

 sphere in an open vessel. If any notable quanti- 

 ty of sulphate of lime (s;ypsum) existed in the 

 soil, a while precipitate will gradually form in the 

 fluid, and the weight of it will indicate the pro- 

 portion. 



Phosphate of lime, if any exist, may be sepa- 

 rated from the soil after the process for gypsum. 

 Muriatic acid must be digested upon the soil, in 

 quantity more than sufficient to saturate the solu- 

 ble earths; the solution must be evaporated, and 

 water poured upon the solid matter. This fluid 

 will dissolve the compounds of earihs with the 

 muriatic acid, and leave the phosphate of lime 

 untouched. It would not fall within the limits as- 

 signed to this lecture to detail any processes for 

 the detection of substances which may be acci- 

 dentally mixed with the matters of soils. Other 

 earihs and metallic oxides are now and then found 

 in them, but in quantities too minute to bear any 

 relaiion to fertility or barrenness, and the search 

 for them would make the analysis much more 

 complicated, without rendering it more useful. 



10. When the examination of a soil is com- 

 pleted, the |)roducts should be numerically arrang- 

 ed, and their quantities added together ; and if 

 they nearly equal the original quantity of soil, 

 the analysis may be considered as accurate. It 

 must, however, be noticed, that when phosphate 

 or sulphate of lime is discovered by the indepen- 

 dent process just described (9), a correction must 

 be made for the general process, by subtracting a 

 sum equal lo their weight from the quantity of 

 carbonate of lime obtained by precipitation from 

 the muriatic acid. 



In arranging ihe products, the form should be 

 in the order of the experiments by which they 

 were procured. 



Thus, I obtained from 400 grains of a good si- 

 liceous sandy soil Irom a hop-garden near Tun- 

 bridge, Kent, 



Of water of absorption 



Of loose stones and gravel, princi- 

 pally siliceous - _ . 



Of undecompounded vegetable fibres 



Of fine siliceous sand 



Of minutely divided matter separa- 

 ted by agitation and filtration, and con- 

 sistiuij of 



Carbonate of lime . - 



Carbonate of magnesia 



Matter destructible by heat, princi- 

 pally vegetable - - 



Silica - - - 



Alumina - - 



Oxide of iron - - 



Grains. 

 19 



53 



14 



212 



19 

 3 



15 



21 



13 



5 



